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Author SHA1 Message Date
Tim Chen
9a574ea906 tick/sched: Preserve number of idle sleeps across CPU hotplug events 
Commit 71fee48f ("tick-sched: Fix idle and iowait sleeptime accounting vs
CPU hotplug") preserved total idle sleep time and iowait sleeptime across
CPU hotplug events.

Similar reasoning applies to the number of idle calls and idle sleeps to
get the proper average of sleep time per idle invocation.

Preserve those fields too.

Fixes: 71fee48f ("tick-sched: Fix idle and iowait sleeptime accounting vs CPU hotplug")
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240122233534.3094238-1-tim.c.chen@linux.intel.com
 2024-01-25 09:52:40 +01:00
Jiri Wiesner
6446495535 clocksource: Skip watchdog check for large watchdog intervals 
There have been reports of the watchdog marking clocksources unstable on
machines with 8 NUMA nodes:

  clocksource: timekeeping watchdog on CPU373:
  Marking clocksource 'tsc' as unstable because the skew is too large:
  clocksource:   'hpet' wd_nsec: 14523447520
  clocksource:   'tsc'  cs_nsec: 14524115132

The measured clocksource skew - the absolute difference between cs_nsec
and wd_nsec - was 668 microseconds:

  cs_nsec - wd_nsec = 14524115132 - 14523447520 = 667612

The kernel used 200 microseconds for the uncertainty_margin of both the
clocksource and watchdog, resulting in a threshold of 400 microseconds (the
md variable). Both the cs_nsec and the wd_nsec value indicate that the
readout interval was circa 14.5 seconds.  The observed behaviour is that
watchdog checks failed for large readout intervals on 8 NUMA node
machines. This indicates that the size of the skew was directly proportinal
to the length of the readout interval on those machines. The measured
clocksource skew, 668 microseconds, was evaluated against a threshold (the
md variable) that is suited for readout intervals of roughly
WATCHDOG_INTERVAL, i.e. HZ >> 1, which is 0.5 second.

The intention of 2e27e793e2 ("clocksource: Reduce clocksource-skew
threshold") was to tighten the threshold for evaluating skew and set the
lower bound for the uncertainty_margin of clocksources to twice
WATCHDOG_MAX_SKEW. Later in c37e85c135 ("clocksource: Loosen clocksource
watchdog constraints"), the WATCHDOG_MAX_SKEW constant was increased to
125 microseconds to fit the limit of NTP, which is able to use a
clocksource that suffers from up to 500 microseconds of skew per second.
Both the TSC and the HPET use default uncertainty_margin. When the
readout interval gets stretched the default uncertainty_margin is no
longer a suitable lower bound for evaluating skew - it imposes a limit
that is far stricter than the skew with which NTP can deal.

The root causes of the skew being directly proportinal to the length of
the readout interval are:

  * the inaccuracy of the shift/mult pairs of clocksources and the watchdog
  * the conversion to nanoseconds is imprecise for large readout intervals

Prevent this by skipping the current watchdog check if the readout
interval exceeds 2 * WATCHDOG_INTERVAL. Considering the maximum readout
interval of 2 * WATCHDOG_INTERVAL, the current default uncertainty margin
(of the TSC and HPET) corresponds to a limit on clocksource skew of 250
ppm (microseconds of skew per second).  To keep the limit imposed by NTP
(500 microseconds of skew per second) for all possible readout intervals,
the margins would have to be scaled so that the threshold value is
proportional to the length of the actual readout interval.

As for why the readout interval may get stretched: Since the watchdog is
executed in softirq context the expiration of the watchdog timer can get
severely delayed on account of a ksoftirqd thread not getting to run in a
timely manner. Surely, a system with such belated softirq execution is not
working well and the scheduling issue should be looked into but the
clocksource watchdog should be able to deal with it accordingly.

Fixes: 2e27e793e2 ("clocksource: Reduce clocksource-skew threshold")
Suggested-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Jiri Wiesner <jwiesner@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240122172350.GA740@incl
 2024-01-25 09:13:16 +01:00
Linus Torvalds
4fbbed7872 Updates for time and clocksources: 
- A fix for the idle and iowait time accounting vs. CPU hotplug.
     The time is reset on CPU hotplug which makes the accumulated
     systemwide time jump backwards.
 
  - Assorted fixes and improvements for clocksource/event drivers
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Merge tag 'timers-core-2024-01-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "Updates for time and clocksources:

   - A fix for the idle and iowait time accounting vs CPU hotplug.

     The time is reset on CPU hotplug which makes the accumulated
     systemwide time jump backwards.

   - Assorted fixes and improvements for clocksource/event drivers"

* tag 'timers-core-2024-01-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick-sched: Fix idle and iowait sleeptime accounting vs CPU hotplug
  clocksource/drivers/ep93xx: Fix error handling during probe
  clocksource/drivers/cadence-ttc: Fix some kernel-doc warnings
  clocksource/drivers/timer-ti-dm: Fix make W=n kerneldoc warnings
  clocksource/timer-riscv: Add riscv_clock_shutdown callback
  dt-bindings: timer: Add StarFive JH8100 clint
  dt-bindings: timer: thead,c900-aclint-mtimer: separate mtime and mtimecmp regs
 2024-01-21 11:14:40 -08:00
Heiko Carstens
71fee48fb7 tick-sched: Fix idle and iowait sleeptime accounting vs CPU hotplug 
When offlining and onlining CPUs the overall reported idle and iowait
times as reported by /proc/stat jump backward and forward:

cpu  132 0 176 225249 47 6 6 21 0 0
cpu0 80 0 115 112575 33 3 4 18 0 0
cpu1 52 0 60 112673 13 3 1 2 0 0

cpu  133 0 177 226681 47 6 6 21 0 0
cpu0 80 0 116 113387 33 3 4 18 0 0

cpu  133 0 178 114431 33 6 6 21 0 0 <---- jump backward
cpu0 80 0 116 114247 33 3 4 18 0 0
cpu1 52 0 61 183 0 3 1 2 0 0        <---- idle + iowait start with 0

cpu  133 0 178 228956 47 6 6 21 0 0 <---- jump forward
cpu0 81 0 117 114929 33 3 4 18 0 0

Reason for this is that get_idle_time() in fs/proc/stat.c has different
sources for both values depending on if a CPU is online or offline:

- if a CPU is online the values may be taken from its per cpu
  tick_cpu_sched structure

- if a CPU is offline the values are taken from its per cpu cpustat
  structure

The problem is that the per cpu tick_cpu_sched structure is set to zero on
CPU offline. See tick_cancel_sched_timer() in kernel/time/tick-sched.c.

Therefore when a CPU is brought offline and online afterwards both its idle
and iowait sleeptime will be zero, causing a jump backward in total system
idle and iowait sleeptime. In a similar way if a CPU is then brought
offline again the total idle and iowait sleeptimes will jump forward.

It looks like this behavior was introduced with commit 4b0c0f294f
("tick: Cleanup NOHZ per cpu data on cpu down").

This was only noticed now on s390, since we switched to generic idle time
reporting with commit be76ea6144 ("s390/idle: remove arch_cpu_idle_time()
and corresponding code").

Fix this by preserving the values of idle_sleeptime and iowait_sleeptime
members of the per-cpu tick_sched structure on CPU hotplug.

Fixes: 4b0c0f294f ("tick: Cleanup NOHZ per cpu data on cpu down")
Reported-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240115163555.1004144-1-hca@linux.ibm.com
 2024-01-19 16:40:38 +01:00
Linus Torvalds
f24dc33f8e Timer subsystem changes for v6.8: 
- Various preparatory cleanups & enhancements of the timer-wheel code,
    in preparation for the WIP 'pull timers at expiry' timer migration model
    series (which will replace the current 'push timers at enqueue' migration
    model), by Anna-Maria Behnsen:
 
       - Update comments and clean up confusing variable names
 
       - Add debug check to warn about time travel
 
       - Improve/expand timer-wheel tracepoints
 
       - Optimize away unnecessary IPIs for deferrable timers
 
       - Restructure & clean up next_expiry_recalc()
 
       - Clean up forward_timer_base()
 
       - Introduce __forward_timer_base() and use it to simplify
         and micro-optimize get_next_timer_interrupt()
 
  - Restructure the get_next_timer_interrupt()'s idle logic
    for better readability and to enable a minor optimization.
 
  - Fix the nextevt calculation when no timers are pending
 
  - Fix the sysfs_get_uname() prototype declaration
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'timers-core-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer subsystem updates from Ingo Molnar:

 - Various preparatory cleanups & enhancements of the timer-wheel code,
   in preparation for the WIP 'pull timers at expiry' timer migration
   model series (which will replace the current 'push timers at enqueue'
   migration model), by Anna-Maria Behnsen:

      - Update comments and clean up confusing variable names

      - Add debug check to warn about time travel

      - Improve/expand timer-wheel tracepoints

      - Optimize away unnecessary IPIs for deferrable timers

      - Restructure & clean up next_expiry_recalc()

      - Clean up forward_timer_base()

      - Introduce __forward_timer_base() and use it to simplify and
        micro-optimize get_next_timer_interrupt()

 - Restructure the get_next_timer_interrupt()'s idle logic for better
   readability and to enable a minor optimization.

 - Fix the nextevt calculation when no timers are pending

 - Fix the sysfs_get_uname() prototype declaration

* tag 'timers-core-2024-01-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timers: Fix nextevt calculation when no timers are pending
  timers: Rework idle logic
  timers: Use already existing function for forwarding timer base
  timers: Split out forward timer base functionality
  timers: Clarify check in forward_timer_base()
  timers: Move store of next event into __next_timer_interrupt()
  timers: Do not IPI for deferrable timers
  tracing/timers: Add tracepoint for tracking timer base is_idle flag
  tracing/timers: Enhance timer_start tracepoint
  tick-sched: Warn when next tick seems to be in the past
  tick/sched: Cleanup confusing variables
  tick-sched: Fix function names in comments
  time: Make sysfs_get_uname() function visible in header
 2024-01-08 18:44:11 -08:00
Linus Torvalds
a4aebe9365 posix-timers: Get rid of [COMPAT_]SYS_NI() uses 
Only the posix timer system calls use this (when the posix timer support
is disabled, which does not actually happen in any normal case), because
they had debug code to print out a warning about missing system calls.

Get rid of that special case, and just use the standard COND_SYSCALL
interface that creates weak system call stubs that return -ENOSYS for
when the system call does not exist.

This fixes a kCFI issue with the SYS_NI() hackery:

  CFI failure at int80_emulation+0x67/0xb0 (target: sys_ni_posix_timers+0x0/0x70; expected type: 0xb02b34d9)
  WARNING: CPU: 0 PID: 48 at int80_emulation+0x67/0xb0

Reported-by: kernel test robot <oliver.sang@intel.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2023-12-20 21:30:27 -08:00
Anna-Maria Behnsen
da65f29dad timers: Fix nextevt calculation when no timers are pending 
When no timer is queued into an empty timer base, the next_expiry will not
be updated. It was originally calculated as

  base->clk + NEXT_TIMER_MAX_DELTA

When the timer base stays empty long enough (> NEXT_TIMER_MAX_DELTA), the
next_expiry value of the empty base suggests that there is a timer pending
soon. This might be more a kind of a theoretical problem, but the fix
doesn't hurt.

Use only base->next_expiry value as nextevt when timers are
pending. Otherwise nextevt will be jiffies + NEXT_TIMER_MAX_DELTA. As all
information is in place, update base->next_expiry value of the empty timer
base as well.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-13-anna-maria@linutronix.de
 2023-12-20 16:49:39 +01:00
Thomas Gleixner
bb8caad508 timers: Rework idle logic 
To improve readability of the code, split base->idle calculation and
expires calculation into separate parts. While at it, update the comment
about timer base idle marking.

Thereby the following subtle change happens if the next event is just one
jiffy ahead and the tick was already stopped: Originally base->is_idle
remains true in this situation. Now base->is_idle turns to false. This may
spare an IPI if a timer is enqueued remotely to an idle CPU that is going
to tick on the next jiffy.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-12-anna-maria@linutronix.de
 2023-12-20 16:49:39 +01:00
Anna-Maria Behnsen
7a39a5080e timers: Use already existing function for forwarding timer base 
There is an already existing function for forwarding the timer
base. Forwarding the timer base is implemented directly in
get_next_timer_interrupt() as well.

Remove the code duplication and invoke __forward_timer_base() instead.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-11-anna-maria@linutronix.de
 2023-12-20 16:49:38 +01:00
Anna-Maria Behnsen
1e490484aa timers: Split out forward timer base functionality 
Forwarding timer base is done when the next expiry value is calculated and
when a new timer is enqueued. When the next expiry value is calculated the
jiffies value is already available and does not need to be reread a second
time.

Splitting out the forward timer base functionality to make it executable
via both contextes - those where jiffies are already known and those, where
jiffies need to be read.

No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-10-anna-maria@linutronix.de
 2023-12-20 16:49:38 +01:00
Anna-Maria Behnsen
8a2c9c7e78 timers: Clarify check in forward_timer_base() 
The current check whether a forward of the timer base is required can be
simplified by using an already existing comparison function which is easier
to read. The related comment is outdated and was not updated when the check
changed in commit 36cd28a4cd ("timers: Lower base clock forwarding
threshold").

Use time_before_eq() for the check and replace the comment by copying the
comment from the same check inside get_next_timer_interrupt(). Move the
precious information of the outdated comment to the proper place in
__run_timers().

No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-9-anna-maria@linutronix.de
 2023-12-20 16:49:38 +01:00
Anna-Maria Behnsen
b5e6f59888 timers: Move store of next event into __next_timer_interrupt() 
Both call sites of __next_timer_interrupt() store the return value directly
in base->next_expiry. Move the store into __next_timer_interrupt() and to
make its purpose more clear, rename the function to next_expiry_recalc().

No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-8-anna-maria@linutronix.de
 2023-12-20 16:49:38 +01:00
Anna-Maria Behnsen
d124c3393e timers: Do not IPI for deferrable timers 
Deferrable timers do not prevent CPU from going idle and are not taken into
account on idle path. Sending an IPI to a remote CPU when a new first
deferrable timer was enqueued will wake up the remote CPU but nothing will
be done regarding the deferrable timers.

Drop IPI completely when a new first deferrable timer was enqueued.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-7-anna-maria@linutronix.de
 2023-12-20 16:49:38 +01:00
Anna-Maria Behnsen
b573c73101 tracing/timers: Add tracepoint for tracking timer base is_idle flag 
When debugging timer code the timer tracepoints are very important. There
is no tracepoint when the is_idle flag of the timer base changes. Instead
of always adding manually trace_printk(), add tracepoints which can be
easily enabled whenever required.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-6-anna-maria@linutronix.de
 2023-12-20 16:49:38 +01:00
Anna-Maria Behnsen
dbcdcb62b5 tracing/timers: Enhance timer_start tracepoint 
For starting a timer, the timer is enqueued into a bucket of the timer
wheel. The bucket expiry is the defacto expiry of the timer but it is not
equal the timer expiry because of increasing granularity when bucket is in
a higher level of the wheel. To be able to figure out in a trace whether a
timer expired in time or not, the bucket expiry time is required as well.

Add bucket expiry time to the timer_start tracepoint and thereby simplify
the arguments.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-5-anna-maria@linutronix.de
 2023-12-20 16:49:38 +01:00
Anna-Maria Behnsen
cbf04a2202 tick-sched: Warn when next tick seems to be in the past 
When the next tick is in the past, the delta between basemono and the next
tick gets negativ. But the next tick should never be in the past. The
negative effect of a wrong next tick might be a stop of the tick and timers
might expire late.

To prevent expensive debugging when changing underlying code, add a
WARN_ON_ONCE into this code path. To prevent complete misbehaviour, also
reset next_tick to basemono in this case.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-4-anna-maria@linutronix.de
 2023-12-20 16:49:38 +01:00
Anna-Maria Behnsen
318050671a tick/sched: Cleanup confusing variables 
tick_nohz_stop_tick() contains the expires (u64 variable) and tick
(ktime_t) variable. In the beginning the value of expires is written to
tick. Afterwards none of the variables is changed. They are only used for
checks.

Drop the not required variable tick and use always expires instead.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-3-anna-maria@linutronix.de
 2023-12-20 16:49:37 +01:00
Anna-Maria Behnsen
cb665db94f tick-sched: Fix function names in comments 
When referencing functions in comments, it might be helpful to use full
function names (including the prefix) to be able to find it when grepping.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-2-anna-maria@linutronix.de
 2023-12-20 16:49:37 +01:00
Arnd Bergmann
a89299c409 time: Make sysfs_get_uname() function visible in header 
This function is defined globally in clocksource.c and used conditionally
in clockevent.c, which the declaration hidden when clockevent support
is disabled. This causes a harmless warning in the definition:

kernel/time/clocksource.c:1324:9: warning: no previous prototype for 'sysfs_get_uname' [-Wmissing-prototypes]
 1324 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt)

Move the declaration out of the #ifdef so it is always visible.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231108125843.3806765-5-arnd@kernel.org
 2023-11-22 14:12:10 +01:00
Linus Torvalds
b0014556a2 - Do the push of pending hrtimers away from a CPU which is being 
offlined earlier in the offlining process in order to prevent
   a deadlock
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Merge tag 'timers_urgent_for_v6.7_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fix from Borislav Petkov:

 - Do the push of pending hrtimers away from a CPU which is being
   offlined earlier in the offlining process in order to prevent a
   deadlock

* tag 'timers_urgent_for_v6.7_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hrtimers: Push pending hrtimers away from outgoing CPU earlier
 2023-11-19 13:35:07 -08:00
Thomas Gleixner
5c0930ccaa hrtimers: Push pending hrtimers away from outgoing CPU earlier 
2b8272ff4a ("cpu/hotplug: Prevent self deadlock on CPU hot-unplug")
solved the straight forward CPU hotplug deadlock vs. the scheduler
bandwidth timer. Yu discovered a more involved variant where a task which
has a bandwidth timer started on the outgoing CPU holds a lock and then
gets throttled. If the lock required by one of the CPU hotplug callbacks
the hotplug operation deadlocks because the unthrottling timer event is not
handled on the dying CPU and can only be recovered once the control CPU
reaches the hotplug state which pulls the pending hrtimers from the dead
CPU.

Solve this by pushing the hrtimers away from the dying CPU in the dying
callbacks. Nothing can queue a hrtimer on the dying CPU at that point because
all other CPUs spin in stop_machine() with interrupts disabled and once the
operation is finished the CPU is marked offline.

Reported-by: Yu Liao <liaoyu15@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Liu Tie <liutie4@huawei.com>
Link: https://lore.kernel.org/r/87a5rphara.ffs@tglx
 2023-11-11 18:06:42 +01:00
Linus Torvalds
89ed67ef12 Networking changes for 6.7. 
Core & protocols
 ----------------
 
  - Support usec resolution of TCP timestamps, enabled selectively by
    a route attribute.
 
  - Defer regular TCP ACK while processing socket backlog, try to send
    a cumulative ACK at the end. Increase single TCP flow performance
    on a 200Gbit NIC by 20% (100Gbit -> 120Gbit).
 
  - The Fair Queuing (FQ) packet scheduler:
    - add built-in 3 band prio / WRR scheduling
    - support bypass if the qdisc is mostly idle (5% speed up for TCP RR)
    - improve inactive flow reporting
    - optimize the layout of structures for better cache locality
 
  - Support TCP Authentication Option (RFC 5925, TCP-AO), a more modern
    replacement for the old MD5 option.
 
  - Add more retransmission timeout (RTO) related statistics to TCP_INFO.
 
  - Support sending fragmented skbs over vsock sockets.
 
  - Make sure we send SIGPIPE for vsock sockets if socket was shutdown().
 
  - Add sysctl for ignoring lower limit on lifetime in Router
    Advertisement PIO, based on an in-progress IETF draft.
 
  - Add sysctl to control activation of TCP ping-pong mode.
 
  - Add sysctl to make connection timeout in MPTCP configurable.
 
  - Support rcvlowat and notsent_lowat on MPTCP sockets, to help apps
    limit the number of wakeups.
 
  - Support netlink GET for MDB (multicast forwarding), allowing user
    space to request a single MDB entry instead of dumping the entire
    table.
 
  - Support selective FDB flushing in the VXLAN tunnel driver.
 
  - Allow limiting learned FDB entries in bridges, prevent OOM attacks.
 
  - Allow controlling via configfs netconsole targets which were created
    via the kernel cmdline at boot, rather than via configfs at runtime.
 
  - Support multiple PTP timestamp event queue readers with different
    filters.
 
  - MCTP over I3C.
 
 BPF
 ---
 
  - Add new veth-like netdevice where BPF program defines the logic
    of the xmit routine. It can operate in L3 and L2 mode.
 
  - Support exceptions - allow asserting conditions which should
    never be true but are hard for the verifier to infer.
    With some extra flexibility around handling of the exit / failure.
    https://lwn.net/Articles/938435/
 
  - Add support for local per-cpu kptr, allow allocating and storing
    per-cpu objects in maps. Access to those objects operates on
    the value for the current CPU. This allows to deprecate local
    one-off implementations of per-CPU storage like
    BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE maps.
 
  - Extend cgroup BPF sockaddr hooks for UNIX sockets. The use case is
    for systemd to re-implement the LogNamespace feature which allows
    running multiple instances of systemd-journald to process the logs
    of different services.
 
  - Enable open-coded task_vma iteration, after maple tree conversion
    made it hard to directly walk VMAs in tracing programs.
 
  - Add open-coded task, css_task and css iterator support.
    One of the use cases is customizable OOM victim selection via BPF.
 
  - Allow source address selection with bpf_*_fib_lookup().
 
  - Add ability to pin BPF timer to the current CPU.
 
  - Prevent creation of infinite loops by combining tail calls and
    fentry/fexit programs.
 
  - Add missed stats for kprobes to retrieve the number of missed kprobe
    executions and subsequent executions of BPF programs.
 
  - Inherit system settings for CPU security mitigations.
 
  - Add BPF v4 CPU instruction support for arm32 and s390x.
 
 Changes to common code
 ----------------------
 
  - overflow: add DEFINE_FLEX() for on-stack definition of structs
    with flexible array members.
 
  - Process doc update with more guidance for reviewers.
 
 Driver API
 ----------
 
  - Simplify locking in WiFi (cfg80211 and mac80211 layers), use wiphy
    mutex in most places and remove a lot of smaller locks.
 
  - Create a common DPLL configuration API. Allow configuring
    and querying state of PLL circuits used for clock syntonization,
    in network time distribution.
 
  - Unify fragmented and full page allocation APIs in page pool code.
    Let drivers be ignorant of PAGE_SIZE.
 
  - Rework PHY state machine to avoid races with calls to phy_stop().
 
  - Notify DSA drivers of MAC address changes on user ports, improve
    correctness of offloads which depend on matching port MAC addresses.
 
  - Allow antenna control on injected WiFi frames.
 
  - Reduce the number of variants of napi_schedule().
 
  - Simplify error handling when composing devlink health messages.
 
 Misc
 ----
 
  - A lot of KCSAN data race "fixes", from Eric.
 
  - A lot of __counted_by() annotations, from Kees.
 
  - A lot of strncpy -> strscpy and printf format fixes.
 
  - Replace master/slave terminology with conduit/user in DSA drivers.
 
  - Handful of KUnit tests for netdev and WiFi core.
 
 Removed
 -------
 
  - AppleTalk COPS.
 
  - AppleTalk ipddp.
 
  - TI AR7 CPMAC Ethernet driver.
 
 Drivers
 -------
 
  - Ethernet high-speed NICs:
    - Intel (100G, ice, idpf):
      - add a driver for the Intel E2000 IPUs
      - make CRC/FCS stripping configurable
      - cross-timestamping for E823 devices
      - basic support for E830 devices
      - use aux-bus for managing client drivers
      - i40e: report firmware versions via devlink
    - nVidia/Mellanox:
      - support 4-port NICs
      - increase max number of channels to 256
      - optimize / parallelize SF creation flow
    - Broadcom (bnxt):
      - enhance NIC temperature reporting
      - support PAM4 speeds and lane configuration
    - Marvell OcteonTX2:
      - PTP pulse-per-second output support
      - enable hardware timestamping for VFs
    - Solarflare/AMD:
      - conntrack NAT offload and offload for tunnels
    - Wangxun (ngbe/txgbe):
      - expose HW statistics
    - Pensando/AMD:
      - support PCI level reset
      - narrow down the condition under which skbs are linearized
    - Netronome/Corigine (nfp):
      - support CHACHA20-POLY1305 crypto in IPsec offload
 
  - Ethernet NICs embedded, slower, virtual:
    - Synopsys (stmmac):
      - add Loongson-1 SoC support
      - enable use of HW queues with no offload capabilities
      - enable PPS input support on all 5 channels
      - increase TX coalesce timer to 5ms
    - RealTek USB (r8152): improve efficiency of Rx by using GRO frags
    - xen: support SW packet timestamping
    - add drivers for implementations based on TI's PRUSS (AM64x EVM)
 
  - nVidia/Mellanox Ethernet datacenter switches:
    - avoid poor HW resource use on Spectrum-4 by better block selection
      for IPv6 multicast forwarding and ordering of blocks in ACL region
 
  - Ethernet embedded switches:
    - Microchip:
      - support configuring the drive strength for EMI compliance
      - ksz9477: partial ACL support
      - ksz9477: HSR offload
      - ksz9477: Wake on LAN
    - Realtek:
      - rtl8366rb: respect device tree config of the CPU port
 
  - Ethernet PHYs:
    - support Broadcom BCM5221 PHYs
    - TI dp83867: support hardware LED blinking
 
  - CAN:
    - add support for Linux-PHY based CAN transceivers
    - at91_can: clean up and use rx-offload helpers
 
  - WiFi:
    - MediaTek (mt76):
      - new sub-driver for mt7925 USB/PCIe devices
      - HW wireless <> Ethernet bridging in MT7988 chips
      - mt7603/mt7628 stability improvements
    - Qualcomm (ath12k):
      - WCN7850:
        - enable 320 MHz channels in 6 GHz band
        - hardware rfkill support
        - enable IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS
          to make scan faster
        - read board data variant name from SMBIOS
      - QCN9274: mesh support
    - RealTek (rtw89):
      - TDMA-based multi-channel concurrency (MCC)
    - Silicon Labs (wfx):
      - Remain-On-Channel (ROC) support
 
  - Bluetooth:
    - ISO: many improvements for broadcast support
    - mark BCM4378/BCM4387 as BROKEN_LE_CODED
    - add support for QCA2066
    - btmtksdio: enable Bluetooth wakeup from suspend
 
 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-next-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Jakub Kicinski:
 "Core & protocols:

   - Support usec resolution of TCP timestamps, enabled selectively by a
     route attribute.

   - Defer regular TCP ACK while processing socket backlog, try to send
     a cumulative ACK at the end. Increase single TCP flow performance
     on a 200Gbit NIC by 20% (100Gbit -> 120Gbit).

   - The Fair Queuing (FQ) packet scheduler:
       - add built-in 3 band prio / WRR scheduling
       - support bypass if the qdisc is mostly idle (5% speed up for TCP RR)
       - improve inactive flow reporting
       - optimize the layout of structures for better cache locality

   - Support TCP Authentication Option (RFC 5925, TCP-AO), a more modern
     replacement for the old MD5 option.

   - Add more retransmission timeout (RTO) related statistics to
     TCP_INFO.

   - Support sending fragmented skbs over vsock sockets.

   - Make sure we send SIGPIPE for vsock sockets if socket was
     shutdown().

   - Add sysctl for ignoring lower limit on lifetime in Router
     Advertisement PIO, based on an in-progress IETF draft.

   - Add sysctl to control activation of TCP ping-pong mode.

   - Add sysctl to make connection timeout in MPTCP configurable.

   - Support rcvlowat and notsent_lowat on MPTCP sockets, to help apps
     limit the number of wakeups.

   - Support netlink GET for MDB (multicast forwarding), allowing user
     space to request a single MDB entry instead of dumping the entire
     table.

   - Support selective FDB flushing in the VXLAN tunnel driver.

   - Allow limiting learned FDB entries in bridges, prevent OOM attacks.

   - Allow controlling via configfs netconsole targets which were
     created via the kernel cmdline at boot, rather than via configfs at
     runtime.

   - Support multiple PTP timestamp event queue readers with different
     filters.

   - MCTP over I3C.

  BPF:

   - Add new veth-like netdevice where BPF program defines the logic of
     the xmit routine. It can operate in L3 and L2 mode.

   - Support exceptions - allow asserting conditions which should never
     be true but are hard for the verifier to infer. With some extra
     flexibility around handling of the exit / failure:

          https://lwn.net/Articles/938435/

   - Add support for local per-cpu kptr, allow allocating and storing
     per-cpu objects in maps. Access to those objects operates on the
     value for the current CPU.

     This allows to deprecate local one-off implementations of per-CPU
     storage like BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE maps.

   - Extend cgroup BPF sockaddr hooks for UNIX sockets. The use case is
     for systemd to re-implement the LogNamespace feature which allows
     running multiple instances of systemd-journald to process the logs
     of different services.

   - Enable open-coded task_vma iteration, after maple tree conversion
     made it hard to directly walk VMAs in tracing programs.

   - Add open-coded task, css_task and css iterator support. One of the
     use cases is customizable OOM victim selection via BPF.

   - Allow source address selection with bpf_*_fib_lookup().

   - Add ability to pin BPF timer to the current CPU.

   - Prevent creation of infinite loops by combining tail calls and
     fentry/fexit programs.

   - Add missed stats for kprobes to retrieve the number of missed
     kprobe executions and subsequent executions of BPF programs.

   - Inherit system settings for CPU security mitigations.

   - Add BPF v4 CPU instruction support for arm32 and s390x.

  Changes to common code:

   - overflow: add DEFINE_FLEX() for on-stack definition of structs with
     flexible array members.

   - Process doc update with more guidance for reviewers.

  Driver API:

   - Simplify locking in WiFi (cfg80211 and mac80211 layers), use wiphy
     mutex in most places and remove a lot of smaller locks.

   - Create a common DPLL configuration API. Allow configuring and
     querying state of PLL circuits used for clock syntonization, in
     network time distribution.

   - Unify fragmented and full page allocation APIs in page pool code.
     Let drivers be ignorant of PAGE_SIZE.

   - Rework PHY state machine to avoid races with calls to phy_stop().

   - Notify DSA drivers of MAC address changes on user ports, improve
     correctness of offloads which depend on matching port MAC
     addresses.

   - Allow antenna control on injected WiFi frames.

   - Reduce the number of variants of napi_schedule().

   - Simplify error handling when composing devlink health messages.

  Misc:

   - A lot of KCSAN data race "fixes", from Eric.

   - A lot of __counted_by() annotations, from Kees.

   - A lot of strncpy -> strscpy and printf format fixes.

   - Replace master/slave terminology with conduit/user in DSA drivers.

   - Handful of KUnit tests for netdev and WiFi core.

  Removed:

   - AppleTalk COPS.

   - AppleTalk ipddp.

   - TI AR7 CPMAC Ethernet driver.

  Drivers:

   - Ethernet high-speed NICs:
      - Intel (100G, ice, idpf):
         - add a driver for the Intel E2000 IPUs
         - make CRC/FCS stripping configurable
         - cross-timestamping for E823 devices
         - basic support for E830 devices
         - use aux-bus for managing client drivers
         - i40e: report firmware versions via devlink
      - nVidia/Mellanox:
         - support 4-port NICs
         - increase max number of channels to 256
         - optimize / parallelize SF creation flow
      - Broadcom (bnxt):
         - enhance NIC temperature reporting
         - support PAM4 speeds and lane configuration
      - Marvell OcteonTX2:
         - PTP pulse-per-second output support
         - enable hardware timestamping for VFs
      - Solarflare/AMD:
         - conntrack NAT offload and offload for tunnels
      - Wangxun (ngbe/txgbe):
         - expose HW statistics
      - Pensando/AMD:
         - support PCI level reset
         - narrow down the condition under which skbs are linearized
      - Netronome/Corigine (nfp):
         - support CHACHA20-POLY1305 crypto in IPsec offload

   - Ethernet NICs embedded, slower, virtual:
      - Synopsys (stmmac):
         - add Loongson-1 SoC support
         - enable use of HW queues with no offload capabilities
         - enable PPS input support on all 5 channels
         - increase TX coalesce timer to 5ms
      - RealTek USB (r8152): improve efficiency of Rx by using GRO frags
      - xen: support SW packet timestamping
      - add drivers for implementations based on TI's PRUSS (AM64x EVM)

   - nVidia/Mellanox Ethernet datacenter switches:
      - avoid poor HW resource use on Spectrum-4 by better block
        selection for IPv6 multicast forwarding and ordering of blocks
        in ACL region

   - Ethernet embedded switches:
      - Microchip:
         - support configuring the drive strength for EMI compliance
         - ksz9477: partial ACL support
         - ksz9477: HSR offload
         - ksz9477: Wake on LAN
      - Realtek:
         - rtl8366rb: respect device tree config of the CPU port

   - Ethernet PHYs:
      - support Broadcom BCM5221 PHYs
      - TI dp83867: support hardware LED blinking

   - CAN:
      - add support for Linux-PHY based CAN transceivers
      - at91_can: clean up and use rx-offload helpers

   - WiFi:
      - MediaTek (mt76):
         - new sub-driver for mt7925 USB/PCIe devices
         - HW wireless <> Ethernet bridging in MT7988 chips
         - mt7603/mt7628 stability improvements
      - Qualcomm (ath12k):
         - WCN7850:
            - enable 320 MHz channels in 6 GHz band
            - hardware rfkill support
            - enable IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS to
              make scan faster
            - read board data variant name from SMBIOS
        - QCN9274: mesh support
      - RealTek (rtw89):
         - TDMA-based multi-channel concurrency (MCC)
      - Silicon Labs (wfx):
         - Remain-On-Channel (ROC) support

   - Bluetooth:
      - ISO: many improvements for broadcast support
      - mark BCM4378/BCM4387 as BROKEN_LE_CODED
      - add support for QCA2066
      - btmtksdio: enable Bluetooth wakeup from suspend"

* tag 'net-next-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1816 commits)
  net: pcs: xpcs: Add 2500BASE-X case in get state for XPCS drivers
  net: bpf: Use sockopt_lock_sock() in ip_sock_set_tos()
  net: mana: Use xdp_set_features_flag instead of direct assignment
  vxlan: Cleanup IFLA_VXLAN_PORT_RANGE entry in vxlan_get_size()
  iavf: delete the iavf client interface
  iavf: add a common function for undoing the interrupt scheme
  iavf: use unregister_netdev
  iavf: rely on netdev's own registered state
  iavf: fix the waiting time for initial reset
  iavf: in iavf_down, don't queue watchdog_task if comms failed
  iavf: simplify mutex_trylock+sleep loops
  iavf: fix comments about old bit locks
  doc/netlink: Update schema to support cmd-cnt-name and cmd-max-name
  tools: ynl: introduce option to process unknown attributes or types
  ipvlan: properly track tx_errors
  netdevsim: Block until all devices are released
  nfp: using napi_build_skb() to replace build_skb()
  net: dsa: microchip: ksz9477: Fix spelling mistake "Enery" -> "Energy"
  net: dsa: microchip: Ensure Stable PME Pin State for Wake-on-LAN
  net: dsa: microchip: Refactor switch shutdown routine for WoL preparation
  ...
 2023-10-31 05:10:11 -10:00
Xabier Marquiegui
60c6946675 posix-clock: introduce posix_clock_context concept 
Add the necessary structure to support custom private-data per
posix-clock user.

The previous implementation of posix-clock assumed all file open
instances need access to the same clock structure on private_data.

The need for individual data structures per file open instance has been
identified when developing support for multiple timestamp event queue
users for ptp_clock.

Signed-off-by: Xabier Marquiegui <reibax@gmail.com>
Suggested-by: Richard Cochran <richardcochran@gmail.com>
Suggested-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 2023-10-15 20:07:52 +01:00
Guenter Roeck
8ceea12d18 alarmtimer: Use maximum alarm time for suspend 
Some userspace applications use timerfd_create() to request wakeups after
a long period of time. For example, a backup application may request a
wakeup once per week. This is perfectly fine as long as the system does
not try to suspend. However, if the system tries to suspend and the
system's RTC does not support the required alarm timeout, the suspend
operation will fail with an error such as

rtc_cmos 00:01: Alarms can be up to one day in the future
PM: dpm_run_callback(): platform_pm_suspend+0x0/0x4a returns -22
alarmtimer alarmtimer.4.auto: platform_pm_suspend+0x0/0x4a returned -22 after 117 usecs
PM: Device alarmtimer.4.auto failed to suspend: error -22

This results in a refusal to suspend the system, causing substantial
battery drain on affected systems.

To fix the problem, use the maximum alarm time offset as reported by RTC
drivers to set the maximum alarm time. While this may result in early
wakeups from suspend, it is still much better than not suspending at all.

Standardize system behavior if the requested alarm timeout is larger than
the alarm timeout supported by the rtc chip. Currently, in this situation,
the RTC driver will do one of the following:

  - It may return an error.
  - It may limit the alarm timeout to the maximum supported by the rtc chip.
  - It may mask the timeout by the maximum alarm timeout supported by the RTC
    chip (i.e. a requested timeout of 1 day + 1 minute may result in a 1
    minute timeout).

With this in place, if the RTC driver reports the maximum alarm timeout
supported by the RTC chip, the system will always limit the alarm timeout
to the maximum supported by the RTC chip.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/r/20230915152238.1144706-3-linux@roeck-us.net
 2023-10-09 15:03:28 +02:00
Ingo Molnar
6c77437735 tick/nohz: Update comments some more 
Inspired by recent enhancements to comments in kernel/time/tick-sched.c,
go through the entire file and fix/unify its comments:

 - Fix over a dozen typos, spelling mistakes & cases of bad grammar.

 - Re-phrase sentences that I needed to read three times to understand.

    [ I used the following arbitrary rule-of-thumb:
       - if I had to read a comment twice, it was usually my fault,
       - if I had to read it a third time, it was the comment's fault. ]

 - Comma updates:

    - Add commas where needed

    - Remove commas where not needed

    - In cases where a comma is optional, choose one variant and try to
      standardize it over similar sentences in the file.

 - Standardize on standalone 'NOHZ' spelling in free-flowing comments:

      s/nohz/NOHZ
      s/no idle tick/NOHZ

   Still keep 'dynticks' as a popular synonym.

 - Standardize on referring to variable names within free-flowing
   comments with the "'var'" nomenclature, and function names as
   "function_name()".

 - Standardize on '64-bit' and '32-bit':
     s/32bit/32-bit
     s/64bit/64-bit

 - Standardize on 'IRQ work':
     s/irq work/IRQ work

 - A few other tidyups I probably missed to list.

No change in functionality intended - other than one small change to
a syslog output string.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/ZRVCNeMcSQcXS36N@gmail.com
 2023-09-29 23:08:42 +02:00
Frederic Weisbecker
4f7f4409af tick/nohz: Don't shutdown the lowres tick from itself 
In lowres dynticks mode, just like in highres dynticks mode, when there
is no tick to program in the future, the tick eventually gets
deactivated either:

  * From the idle loop if in idle mode.
  * From the IRQ exit if in full dynticks mode.

Therefore there is no need to deactivate it from the tick itself. This
just just brings more overhead in the idle tick path for no reason.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Link: https://lore.kernel.org/r/20230912104406.312185-4-frederic@kernel.org
 2023-09-27 16:58:10 +02:00
Frederic Weisbecker
822deeed3a tick/nohz: Update obsolete comments 
Some comments are obsolete enough to assume that IRQ exit restarts the
tick in idle or RCU is turned on at the same time as the tick, among
other details.

Update them and add more.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230912104406.312185-3-frederic@kernel.org
 2023-09-27 16:58:10 +02:00
Frederic Weisbecker
dba428a678 tick/nohz: Rename the tick handlers to more self-explanatory names 
The current names of the tick handlers don't tell much about what different
between them. Use names that better reflect their role and resolution.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230912104406.312185-2-frederic@kernel.org
 2023-09-27 16:58:10 +02:00
Linus Torvalds
a6216978de Fix false positive "softirq work is pending" messages on -rt 
kernels, caused by a buggy factoring-out of existing code.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'timers-urgent-2023-09-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fix from Ingo Molnar:
 "Fix false positive 'softirq work is pending' messages on -rt kernels,
  caused by a buggy factoring-out of existing code"

* tag 'timers-urgent-2023-09-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick/rcu: Fix false positive "softirq work is pending" messages
 2023-09-02 09:01:48 -07:00
Linus Torvalds
cd99b9eb4b Documentation work keeps chugging along; stuff for 6.6 includes: 
- Work from Carlos Bilbao to integrate rustdoc output into the generated
   HTML documentation.  This took some work to figure out how to do it
   without slowing the docs build and without creating people who don't have
   Rust installed, but Carlos got there.
 
 - Move the loongarch and mips architecture documentation under
   Documentation/arch/.
 
 - Some more maintainer documentation from Jakub
 
 ...plus the usual assortment of updates, translations, and fixes.
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Merge tag 'docs-6.6' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "Documentation work keeps chugging along; this includes:

   - Work from Carlos Bilbao to integrate rustdoc output into the
     generated HTML documentation. This took some work to figure out how
     to do it without slowing the docs build and without creating people
     who don't have Rust installed, but Carlos got there

   - Move the loongarch and mips architecture documentation under
     Documentation/arch/

   - Some more maintainer documentation from Jakub

  ... plus the usual assortment of updates, translations, and fixes"

* tag 'docs-6.6' of git://git.lwn.net/linux: (56 commits)
  Docu: genericirq.rst: fix irq-example
  input: docs: pxrc: remove reference to phoenix-sim
  Documentation: serial-console: Fix literal block marker
  docs/mm: remove references to hmm_mirror ops and clean typos
  docs/zh_CN: correct regi_chg(),regi_add() to region_chg(),region_add()
  Documentation: Fix typos
  Documentation/ABI: Fix typos
  scripts: kernel-doc: fix macro handling in enums
  scripts: kernel-doc: parse DEFINE_DMA_UNMAP_[ADDR|LEN]
  Documentation: riscv: Update boot image header since EFI stub is supported
  Documentation: riscv: Add early boot document
  Documentation: arm: Add bootargs to the table of added DT parameters
  docs: kernel-parameters: Refer to the correct bitmap function
  doc: update params of memhp_default_state=
  docs: Add book to process/kernel-docs.rst
  docs: sparse: fix invalid link addresses
  docs: vfs: clean up after the iterate() removal
  docs: Add a section on surveys to the researcher guidelines
  docs: move mips under arch
  docs: move loongarch under arch
  ...
 2023-08-30 20:05:42 -07:00
Paul Gortmaker
96c1fa04f0 tick/rcu: Fix false positive "softirq work is pending" messages 
In commit 0345691b24 ("tick/rcu: Stop allowing RCU_SOFTIRQ in idle") the
new function report_idle_softirq() was created by breaking code out of the
existing can_stop_idle_tick() for kernels v5.18 and newer.

In doing so, the code essentially went from a one conditional:

	if (a && b && c)
		warn();

to a three conditional:

	if (!a)
		return;
	if (!b)
		return;
	if (!c)
		return;
	warn();

But that conversion got the condition for the RT specific
local_bh_blocked() wrong. The original condition was:

   	!local_bh_blocked()

but the conversion failed to negate it so it ended up as:

        if (!local_bh_blocked())
		return false;

This issue lay dormant until another fixup for the same commit was added
in commit a7e282c777 ("tick/rcu: Fix bogus ratelimit condition").
This commit realized the ratelimit was essentially set to zero instead
of ten, and hence *no* softirq pending messages would ever be issued.

Once this commit was backported via linux-stable, both the v6.1 and v6.4
preempt-rt kernels started printing out 10 instances of this at boot:

  NOHZ tick-stop error: local softirq work is pending, handler #80!!!

Remove the negation and return when local_bh_blocked() evaluates to true to
bring the correct behaviour back.

Fixes: 0345691b24 ("tick/rcu: Stop allowing RCU_SOFTIRQ in idle")
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Wen Yang <wenyang.linux@foxmail.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230818200757.1808398-1-paul.gortmaker@windriver.com
 2023-08-30 12:20:28 +02:00
Linus Torvalds
815c24a085 linux-kselftest-kunit-6.6-rc1 
This kunit update for Linux 6.6.rc1 consists of:
 
 -- Adds support for running Rust documentation tests as KUnit tests
 -- Makes init, str, sync, types doctests compilable/testable
 -- Adds support for attributes API which include speed, modules
    attributes, ability to filter and report attributes.
 -- Adds support for marking tests slow using attributes API.
 -- Adds attributes API documentation
 -- Fixes to wild-memory-access bug in kunit_filter_suites() and
    a possible memory leak in kunit_filter_suites()
 -- Adds support for counting number of test suites in a module, list
    action to kunit test modules, and test filtering on module tests.
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Merge tag 'linux-kselftest-kunit-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull kunit updates from Shuah Khan:

 - add support for running Rust documentation tests as KUnit tests

 - make init, str, sync, types doctests compilable/testable

 - add support for attributes API which include speed, modules
   attributes, ability to filter and report attributes

 - add support for marking tests slow using attributes API

 - add attributes API documentation

 - fix a wild-memory-access bug in kunit_filter_suites() and a possible
   memory leak in kunit_filter_suites()

 - add support for counting number of test suites in a module, list
   action to kunit test modules, and test filtering on module tests

* tag 'linux-kselftest-kunit-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (25 commits)
  kunit: fix struct kunit_attr header
  kunit: replace KUNIT_TRIGGER_STATIC_STUB maro with KUNIT_STATIC_STUB_REDIRECT
  kunit: Allow kunit test modules to use test filtering
  kunit: Make 'list' action available to kunit test modules
  kunit: Report the count of test suites in a module
  kunit: fix uninitialized variables bug in attributes filtering
  kunit: fix possible memory leak in kunit_filter_suites()
  kunit: fix wild-memory-access bug in kunit_filter_suites()
  kunit: Add documentation of KUnit test attributes
  kunit: add tests for filtering attributes
  kunit: time: Mark test as slow using test attributes
  kunit: memcpy: Mark tests as slow using test attributes
  kunit: tool: Add command line interface to filter and report attributes
  kunit: Add ability to filter attributes
  kunit: Add module attribute
  kunit: Add speed attribute
  kunit: Add test attributes API structure
  MAINTAINERS: add Rust KUnit files to the KUnit entry
  rust: support running Rust documentation tests as KUnit ones
  rust: types: make doctests compilable/testable
  ...
 2023-08-28 18:56:38 -07:00
Rae Moar
a547c4ce10 kunit: time: Mark test as slow using test attributes 
Mark the time KUnit test, time64_to_tm_test_date_range, as slow using test
attributes.

This test ran relatively much slower than most other KUnit tests.

By marking this test as slow, the test can now be filtered using the KUnit
test attribute filtering feature. Example: --filter "speed>slow". This will
run only the tests that have speeds faster than slow. The slow attribute
will also be outputted in KTAP.

Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Rae Moar <rmoar@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
 2023-07-26 13:29:35 -06:00
Paul E. McKenney
e40806e9bc clocksource: Handle negative skews in "skew is too large" messages 
The nanosecond-to-millisecond skew computation uses unsigned arithmetic,
which produces user-unfriendly large positive numbers for negative skews.
Therefore, use signed arithmetic for this computation in order to preserve
the negativity.

Reported-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Reported-by: Feng Tang <feng.tang@intel.com>
Fixes: dd02926994 ("clocksource: Improve "skew is too large" messages")
Reviewed-by: Feng Tang <feng.tang@intel.com>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
 2023-07-14 15:17:09 -07:00
Randy Dunlap
67b3f564cb time: add kernel-doc in time.c 
Add kernel-doc for all APIs that do not already have it.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: John Stultz <jstultz@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Acked-by: John Stultz <jstultz@google.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230704052405.5089-3-rdunlap@infradead.org
 2023-07-14 13:47:07 -06:00
Linus Torvalds
582c161cf3 hardening updates for v6.5-rc1 
- Fix KMSAN vs FORTIFY in strlcpy/strlcat (Alexander Potapenko)
 
 - Convert strreplace() to return string start (Andy Shevchenko)
 
 - Flexible array conversions (Arnd Bergmann, Wyes Karny, Kees Cook)
 
 - Add missing function prototypes seen with W=1 (Arnd Bergmann)
 
 - Fix strscpy() kerndoc typo (Arne Welzel)
 
 - Replace strlcpy() with strscpy() across many subsystems which were
   either Acked by respective maintainers or were trivial changes that
   went ignored for multiple weeks (Azeem Shaikh)
 
 - Remove unneeded cc-option test for UBSAN_TRAP (Nick Desaulniers)
 
 - Add KUnit tests for strcat()-family
 
 - Enable KUnit tests of FORTIFY wrappers under UML
 
 - Add more complete FORTIFY protections for strlcat()
 
 - Add missed disabling of FORTIFY for all arch purgatories.
 
 - Enable -fstrict-flex-arrays=3 globally
 
 - Tightening UBSAN_BOUNDS when using GCC
 
 - Improve checkpatch to check for strcpy, strncpy, and fake flex arrays
 
 - Improve use of const variables in FORTIFY
 
 - Add requested struct_size_t() helper for types not pointers
 
 - Add __counted_by macro for annotating flexible array size members
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Merge tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:
 "There are three areas of note:

  A bunch of strlcpy()->strscpy() conversions ended up living in my tree
  since they were either Acked by maintainers for me to carry, or got
  ignored for multiple weeks (and were trivial changes).

  The compiler option '-fstrict-flex-arrays=3' has been enabled
  globally, and has been in -next for the entire devel cycle. This
  changes compiler diagnostics (though mainly just -Warray-bounds which
  is disabled) and potential UBSAN_BOUNDS and FORTIFY _warning_
  coverage. In other words, there are no new restrictions, just
  potentially new warnings. Any new FORTIFY warnings we've seen have
  been fixed (usually in their respective subsystem trees). For more
  details, see commit df8fc4e934.

  The under-development compiler attribute __counted_by has been added
  so that we can start annotating flexible array members with their
  associated structure member that tracks the count of flexible array
  elements at run-time. It is possible (likely?) that the exact syntax
  of the attribute will change before it is finalized, but GCC and Clang
  are working together to sort it out. Any changes can be made to the
  macro while we continue to add annotations.

  As an example of that last case, I have a treewide commit waiting with
  such annotations found via Coccinelle:

    https://git.kernel.org/linus/adc5b3cb48a049563dc673f348eab7b6beba8a9b

  Also see commit dd06e72e68 for more details.

  Summary:

   - Fix KMSAN vs FORTIFY in strlcpy/strlcat (Alexander Potapenko)

   - Convert strreplace() to return string start (Andy Shevchenko)

   - Flexible array conversions (Arnd Bergmann, Wyes Karny, Kees Cook)

   - Add missing function prototypes seen with W=1 (Arnd Bergmann)

   - Fix strscpy() kerndoc typo (Arne Welzel)

   - Replace strlcpy() with strscpy() across many subsystems which were
     either Acked by respective maintainers or were trivial changes that
     went ignored for multiple weeks (Azeem Shaikh)

   - Remove unneeded cc-option test for UBSAN_TRAP (Nick Desaulniers)

   - Add KUnit tests for strcat()-family

   - Enable KUnit tests of FORTIFY wrappers under UML

   - Add more complete FORTIFY protections for strlcat()

   - Add missed disabling of FORTIFY for all arch purgatories.

   - Enable -fstrict-flex-arrays=3 globally

   - Tightening UBSAN_BOUNDS when using GCC

   - Improve checkpatch to check for strcpy, strncpy, and fake flex
     arrays

   - Improve use of const variables in FORTIFY

   - Add requested struct_size_t() helper for types not pointers

   - Add __counted_by macro for annotating flexible array size members"

* tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (54 commits)
  netfilter: ipset: Replace strlcpy with strscpy
  uml: Replace strlcpy with strscpy
  um: Use HOST_DIR for mrproper
  kallsyms: Replace all non-returning strlcpy with strscpy
  sh: Replace all non-returning strlcpy with strscpy
  of/flattree: Replace all non-returning strlcpy with strscpy
  sparc64: Replace all non-returning strlcpy with strscpy
  Hexagon: Replace all non-returning strlcpy with strscpy
  kobject: Use return value of strreplace()
  lib/string_helpers: Change returned value of the strreplace()
  jbd2: Avoid printing outside the boundary of the buffer
  checkpatch: Check for 0-length and 1-element arrays
  riscv/purgatory: Do not use fortified string functions
  s390/purgatory: Do not use fortified string functions
  x86/purgatory: Do not use fortified string functions
  acpi: Replace struct acpi_table_slit 1-element array with flex-array
  clocksource: Replace all non-returning strlcpy with strscpy
  string: use __builtin_memcpy() in strlcpy/strlcat
  staging: most: Replace all non-returning strlcpy with strscpy
  drm/i2c: tda998x: Replace all non-returning strlcpy with strscpy
  ...
 2023-06-27 21:24:18 -07:00
Linus Torvalds
ed3b7923a8 Scheduler changes for v6.5: 
- Scheduler SMP load-balancer improvements:
 
     - Avoid unnecessary migrations within SMT domains on hybrid systems.
 
       Problem:
 
         On hybrid CPU systems, (processors with a mixture of higher-frequency
 	SMT cores and lower-frequency non-SMT cores), under the old code
 	lower-priority CPUs pulled tasks from the higher-priority cores if
 	more than one SMT sibling was busy - resulting in many unnecessary
 	task migrations.
 
       Solution:
 
         The new code improves the load balancer to recognize SMT cores with more
         than one busy sibling and allows lower-priority CPUs to pull tasks, which
         avoids superfluous migrations and lets lower-priority cores inspect all SMT
         siblings for the busiest queue.
 
     - Implement the 'runnable boosting' feature in the EAS balancer: consider CPU
       contention in frequency, EAS max util & load-balance busiest CPU selection.
 
       This improves CPU utilization for certain workloads, while leaves other key
       workloads unchanged.
 
 - Scheduler infrastructure improvements:
 
     - Rewrite the scheduler topology setup code by consolidating it
       into the build_sched_topology() helper function and building
       it dynamically on the fly.
 
     - Resolve the local_clock() vs. noinstr complications by rewriting
       the code: provide separate sched_clock_noinstr() and
       local_clock_noinstr() functions to be used in instrumentation code,
       and make sure it is all instrumentation-safe.
 
 - Fixes:
 
     - Fix a kthread_park() race with wait_woken()
 
     - Fix misc wait_task_inactive() bugs unearthed by the -rt merge:
        - Fix UP PREEMPT bug by unifying the SMP and UP implementations.
        - Fix task_struct::saved_state handling.
 
     - Fix various rq clock update bugs, unearthed by turning on the rq clock
       debugging code.
 
     - Fix the PSI WINDOW_MIN_US trigger limit, which was easy to trigger by
       creating enough cgroups, by removing the warnign and restricting
       window size triggers to PSI file write-permission or CAP_SYS_RESOURCE.
 
     - Propagate SMT flags in the topology when removing degenerate domain
 
     - Fix grub_reclaim() calculation bug in the deadline scheduler code
 
     - Avoid resetting the min update period when it is unnecessary, in
       psi_trigger_destroy().
 
     - Don't balance a task to its current running CPU in load_balance(),
       which was possible on certain NUMA topologies with overlapping
       groups.
 
     - Fix the sched-debug printing of rq->nr_uninterruptible
 
 - Cleanups:
 
     - Address various -Wmissing-prototype warnings, as a preparation
       to (maybe) enable this warning in the future.
 
     - Remove unused code
 
     - Mark more functions __init
 
     - Fix shadow-variable warnings
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:
 "Scheduler SMP load-balancer improvements:

   - Avoid unnecessary migrations within SMT domains on hybrid systems.

     Problem:

        On hybrid CPU systems, (processors with a mixture of
        higher-frequency SMT cores and lower-frequency non-SMT cores),
        under the old code lower-priority CPUs pulled tasks from the
        higher-priority cores if more than one SMT sibling was busy -
        resulting in many unnecessary task migrations.

     Solution:

        The new code improves the load balancer to recognize SMT cores
        with more than one busy sibling and allows lower-priority CPUs
        to pull tasks, which avoids superfluous migrations and lets
        lower-priority cores inspect all SMT siblings for the busiest
        queue.

   - Implement the 'runnable boosting' feature in the EAS balancer:
     consider CPU contention in frequency, EAS max util & load-balance
     busiest CPU selection.

     This improves CPU utilization for certain workloads, while leaves
     other key workloads unchanged.

  Scheduler infrastructure improvements:

   - Rewrite the scheduler topology setup code by consolidating it into
     the build_sched_topology() helper function and building it
     dynamically on the fly.

   - Resolve the local_clock() vs. noinstr complications by rewriting
     the code: provide separate sched_clock_noinstr() and
     local_clock_noinstr() functions to be used in instrumentation code,
     and make sure it is all instrumentation-safe.

  Fixes:

   - Fix a kthread_park() race with wait_woken()

   - Fix misc wait_task_inactive() bugs unearthed by the -rt merge:
       - Fix UP PREEMPT bug by unifying the SMP and UP implementations
       - Fix task_struct::saved_state handling

   - Fix various rq clock update bugs, unearthed by turning on the rq
     clock debugging code.

   - Fix the PSI WINDOW_MIN_US trigger limit, which was easy to trigger
     by creating enough cgroups, by removing the warnign and restricting
     window size triggers to PSI file write-permission or
     CAP_SYS_RESOURCE.

   - Propagate SMT flags in the topology when removing degenerate domain

   - Fix grub_reclaim() calculation bug in the deadline scheduler code

   - Avoid resetting the min update period when it is unnecessary, in
     psi_trigger_destroy().

   - Don't balance a task to its current running CPU in load_balance(),
     which was possible on certain NUMA topologies with overlapping
     groups.

   - Fix the sched-debug printing of rq->nr_uninterruptible

  Cleanups:

   - Address various -Wmissing-prototype warnings, as a preparation to
     (maybe) enable this warning in the future.

   - Remove unused code

   - Mark more functions __init

   - Fix shadow-variable warnings"

* tag 'sched-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
  sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle()
  sched/core: Avoid double calling update_rq_clock() in __balance_push_cpu_stop()
  sched/core: Fixed missing rq clock update before calling set_rq_offline()
  sched/deadline: Update GRUB description in the documentation
  sched/deadline: Fix bandwidth reclaim equation in GRUB
  sched/wait: Fix a kthread_park race with wait_woken()
  sched/topology: Mark set_sched_topology() __init
  sched/fair: Rename variable cpu_util eff_util
  arm64/arch_timer: Fix MMIO byteswap
  sched/fair, cpufreq: Introduce 'runnable boosting'
  sched/fair: Refactor CPU utilization functions
  cpuidle: Use local_clock_noinstr()
  sched/clock: Provide local_clock_noinstr()
  x86/tsc: Provide sched_clock_noinstr()
  clocksource: hyper-v: Provide noinstr sched_clock()
  clocksource: hyper-v: Adjust hv_read_tsc_page_tsc() to avoid special casing U64_MAX
  x86/vdso: Fix gettimeofday masking
  math64: Always inline u128 version of mul_u64_u64_shr()
  s390/time: Provide sched_clock_noinstr()
  loongarch: Provide noinstr sched_clock_read()
  ...
 2023-06-27 14:03:21 -07:00
Linus Torvalds
cd336f6562 Time, timekeeping and related device driver updates: 
- Core:
 
    - A set of fixes, cleanups and enhancements to the posix timer code:
 
      - Prevent another possible live lock scenario in the exit() path,
        which affects POSIX_CPU_TIMERS_TASK_WORK enabled architectures.
 
      - Fix a loop termination issue which was reported syzcaller/KSAN in
        the posix timer ID allocation code.
 
        That triggered a deeper look into the posix-timer code which
        unearthed more small issues.
 
      - Add missing READ/WRITE_ONCE() annotations
 
      - Fix or remove completely outdated comments
 
      - Document places which are subtle and completely undocumented.
 
    - Add missing hrtimer modes to the trace event decoder
 
    - Small cleanups and enhancements all over the place
 
  - Drivers:
 
      - Rework the Hyper-V clocksource and sched clock setup code
 
      - Remove a deprecated clocksource driver
 
      - Small fixes and enhancements all over the place
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Merge tag 'timers-core-2023-06-26' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "Time, timekeeping and related device driver updates:

  Core:

   - A set of fixes, cleanups and enhancements to the posix timer code:

       - Prevent another possible live lock scenario in the exit() path,
         which affects POSIX_CPU_TIMERS_TASK_WORK enabled architectures.

       - Fix a loop termination issue which was reported syzcaller/KSAN
         in the posix timer ID allocation code.

         That triggered a deeper look into the posix-timer code which
         unearthed more small issues.

       - Add missing READ/WRITE_ONCE() annotations

       - Fix or remove completely outdated comments

       - Document places which are subtle and completely undocumented.

   - Add missing hrtimer modes to the trace event decoder

   - Small cleanups and enhancements all over the place

  Drivers:

   - Rework the Hyper-V clocksource and sched clock setup code

   - Remove a deprecated clocksource driver

   - Small fixes and enhancements all over the place"

* tag 'timers-core-2023-06-26' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
  clocksource/drivers/cadence-ttc: Fix memory leak in ttc_timer_probe
  dt-bindings: timers: Add Ralink SoCs timer
  clocksource/drivers/hyper-v: Rework clocksource and sched clock setup
  dt-bindings: timer: brcm,kona-timer: convert to YAML
  clocksource/drivers/imx-gpt: Fold <soc/imx/timer.h> into its only user
  clk: imx: Drop inclusion of unused header <soc/imx/timer.h>
  hrtimer: Add missing sparse annotations to hrtimer locking
  clocksource/drivers/imx-gpt: Use only a single name for functions
  clocksource/drivers/loongson1: Move PWM timer to clocksource framework
  dt-bindings: timer: Add Loongson-1 clocksource
  MIPS: Loongson32: Remove deprecated PWM timer clocksource
  clocksource/drivers/ingenic-timer: Use pm_sleep_ptr() macro
  tracing/timer: Add missing hrtimer modes to decode_hrtimer_mode().
  posix-timers: Add sys_ni_posix_timers() prototype
  tick/rcu: Fix bogus ratelimit condition
  alarmtimer: Remove unnecessary (void *) cast
  alarmtimer: Remove unnecessary initialization of variable 'ret'
  posix-timers: Refer properly to CONFIG_HIGH_RES_TIMERS
  posix-timers: Polish coding style in a few places
  posix-timers: Remove pointless comments
  ...
 2023-06-26 14:10:45 -07:00
Ben Dooks
ccaa4926c2 hrtimer: Add missing sparse annotations to hrtimer locking 
Sparse warns about lock imbalance vs. the hrtimer_base lock due to missing
sparse annotations:

kernel/time/hrtimer.c:175:33: warning: context imbalance in 'lock_hrtimer_base' - wrong count at exit
kernel/time/hrtimer.c:1301:28: warning: context imbalance in 'hrtimer_start_range_ns' - unexpected unlock
kernel/time/hrtimer.c:1336:28: warning: context imbalance in 'hrtimer_try_to_cancel' - unexpected unlock
kernel/time/hrtimer.c:1457:9: warning: context imbalance in '__hrtimer_get_remaining' - unexpected unlock

Add the annotations to the relevant functions.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230621075928.394481-1-ben.dooks@codethink.co.uk
 2023-06-22 10:32:37 +02:00
Wen Yang
a7e282c777 tick/rcu: Fix bogus ratelimit condition 
The ratelimit logic in report_idle_softirq() is broken because the
exit condition is always true:

	static int ratelimit;

	if (ratelimit < 10)
		return false;  ---> always returns here

	ratelimit++;           ---> no chance to run

Make it check for >= 10 instead.

Fixes: 0345691b24 ("tick/rcu: Stop allowing RCU_SOFTIRQ in idle")
Signed-off-by: Wen Yang <wenyang.linux@foxmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/tencent_5AAA3EEAB42095C9B7740BE62FBF9A67E007@qq.com
 2023-06-18 22:41:53 +02:00
Li zeming
fc4b4d96f7 alarmtimer: Remove unnecessary (void *) cast 
Pointers of type void * do not require a type cast when they are assigned
to a real pointer.

Signed-off-by: Li zeming <zeming@nfschina.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230609182059.4509-1-zeming@nfschina.com
 2023-06-18 22:41:53 +02:00
Li zeming
986af8dc5a alarmtimer: Remove unnecessary initialization of variable 'ret' 
ret is assigned before checked, so it does not need to initialize the
variable

Signed-off-by: Li zeming <zeming@nfschina.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230609182856.4660-1-zeming@nfschina.com
 2023-06-18 22:41:53 +02:00
Lukas Bulwahn
b9a40f24d8 posix-timers: Refer properly to CONFIG_HIGH_RES_TIMERS 
Commit c78f261e5dcb ("posix-timers: Clarify posix_timer_fn() comments")
turns an ifdef CONFIG_HIGH_RES_TIMERS into an conditional on
"IS_ENABLED(CONFIG_HIGHRES_TIMERS)"; note that the new conditional refers
to "HIGHRES_TIMERS" not "HIGH_RES_TIMERS" as before.

Fix this typo introduced in that refactoring.

Fixes: c78f261e5dcb ("posix-timers: Clarify posix_timer_fn() comments")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230609094643.26253-1-lukas.bulwahn@gmail.com
 2023-06-18 22:41:53 +02:00
Thomas Gleixner
b96ce4931f posix-timers: Polish coding style in a few places 
Make it consistent with the TIP tree documentation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230425183313.888493625@linutronix.de
 2023-06-18 22:41:53 +02:00
Thomas Gleixner
200dbd6d14 posix-timers: Remove pointless comments 
Documenting the obvious is just consuming space for no value.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230425183313.832240451@linutronix.de
 2023-06-18 22:41:52 +02:00
Thomas Gleixner
84999b8bdb posix-timers: Clarify posix_timer_fn() comments 
Make the issues vs. SIG_IGN understandable and remove the 15 years old
promise that a proper solution is already on the horizon.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/874jnrdmrq.ffs@tglx
 2023-06-18 22:41:52 +02:00
Thomas Gleixner
02972d7955 posix-timers: Clarify posix_timer_rearm() comment 
Yet another incomprehensible piece of art.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230425183313.724863461@linutronix.de
 2023-06-18 22:41:52 +02:00
Thomas Gleixner
c575689d66 posix-timers: Comment SIGEV_THREAD_ID properly 
Replace the word salad.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230425183313.672220780@linutronix.de
 2023-06-18 22:41:51 +02:00
Thomas Gleixner
52f090b164 posix-timers: Add proper comments in do_timer_create() 
The comment about timer lifetime at the end of the function is misplaced
and uncomprehensible.

Make it understandable and put it at the right place. Add a new comment
about the visibility of the new timer ID to user space.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230425183313.619897296@linutronix.de
 2023-06-18 22:41:51 +02:00
Thomas Gleixner
640fe745d7 posix-timers: Document nanosleep() details 
The descriptions for common_nsleep() is wrong and common_nsleep_timens()
lacks any form of comment.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230425183313.567072835@linutronix.de
 2023-06-18 22:41:51 +02:00