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a202355640
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Tim Bird a202355640 ring-buffer: fix bug in ring_buffer_discard_commit 
There's a bug in ring_buffer_discard_commit.  The wrong
pointer is being compared in order to check if the event
can be freed from the buffer rather than discarded
(i.e. marked as PAD).

I noticed this when I was working on duration filtering.
The bug is not deadly - it just results in lots of wasted
space in the buffer.  All filtered events are left in
the buffer and marked as discarded, rather than being
removed from the buffer to make space for other events.

Unfortunately, when I fixed this bug, I got errors doing a
filtered function trace.  Multiple TIME_EXTEND
events pile up in the buffer, and trigger the
following loop overage warning in rb_iter_peek():

again:
	...
	if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10))
		return NULL;

I'm not sure what the best way is to fix this. I don't
know if I should extend the loop threshhold, or if I should
make the test more complex (ignore TIME_EXTEND
events), or just get rid of this loop check completely.

Note that if I implement a workaround for this, then I
see another problem from rb_advance_iter().  I haven't
tracked that one down yet.

In general, it seems like the case of removing filtered
events has not been working properly, and so some assumptions
about buffer invariant conditions need to be revisited.

Here's the patch for the simple fix:

Compare correct pointer for checking if an event can be
freed rather than left as discarded in the buffer.

Signed-off-by: Tim Bird <tim.bird@am.sony.com>
LKML-Reference: <4A25BE9E.5090909@am.sony.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-06-03 10:15:06 -04:00
..
irq Merge branch 'linus' into tracing/core 2009-05-07 11:17:34 +02:00
power PM/Hibernate: Fix waiting for image device to appear on resume 2009-04-24 15:31:30 -07:00
time clockevents: prevent endless loop in tick_handle_periodic() 2009-05-02 10:22:27 +02:00
trace ring-buffer: fix bug in ring_buffer_discard_commit 2009-06-03 10:15:06 -04:00
.gitignore
acct.c [CVE-2009-0029] System call wrappers part 04 2009-01-14 14:15:19 +01:00
async.c async: remove the temporary (2.6.29) "async is off by default" code 2009-03-28 13:05:30 -07:00
audit_tree.c No need for crossing to mountpoint in audit_tag_tree() 2009-04-20 23:01:15 -04:00
audit.c Audit: remove spaces from audit_log_d_path 2009-04-05 13:49:04 -04:00
audit.h fixing audit rule ordering mess, part 1 2009-01-04 15:14:41 -05:00
auditfilter.c inotify: use GFP_NOFS in kernel_event() to work around a lockdep false-positive 2009-05-06 16:36:09 -07:00
auditsc.c Audit: remove spaces from audit_log_d_path 2009-04-05 13:49:04 -04:00
backtracetest.c
bounds.c
capability.c [CVE-2009-0029] System call wrappers part 04 2009-01-14 14:15:19 +01:00
cgroup_debug.c debug cgroup: remove unneeded cgroup_lock 2009-04-02 19:04:54 -07:00
cgroup_freezer.c freezer_cg: disable writing freezer.state of root cgroup 2008-11-12 17:17:16 -08:00
cgroup.c Convert obvious places to deactivate_locked_super() 2009-05-09 10:49:40 -04:00
compat.c Allow times and time system calls to return small negative values 2009-01-06 15:59:13 -08:00
configs.c
cpu.c cpumask: use set_cpu_active in init/main.c 2009-03-30 22:05:12 +10:30
cpuset.c cpusets: prevent PF_THREAD_BOUND tasks from attaching to non-root cpusets 2009-04-02 19:04:57 -07:00
cred-internals.h CRED: Inaugurate COW credentials 2008-11-14 10:39:23 +11:00
cred.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6 2009-01-09 13:59:25 -08:00
delayacct.c schedstat: consolidate per-task cpu runtime stats 2008-12-18 13:54:01 +01:00
dma-coherent.c dma-coherent: Restore dma_alloc_from_coherent() large alloc fall back policy. 2009-01-21 18:51:53 +09:00
dma.c
exec_domain.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
exit.c tracing/events: move trace point headers into include/trace/events 2009-04-14 22:05:43 -04:00
extable.c Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
fork.c Merge branch 'tracing/hw-branch-tracing' into tracing/core 2009-05-07 13:36:22 +02:00
freezer.c
futex_compat.c CRED: Use RCU to access another task's creds and to release a task's own creds 2008-11-14 10:39:19 +11:00
futex.c futex: comment requeue key reference semantics 2009-04-02 23:39:53 +02:00
hrtimer.c hrtimer: fix rq->lock inversion (again) 2009-03-31 14:52:52 +02:00
hung_task.c softlockup: ensure the task has been switched out once 2009-02-11 11:04:16 +01:00
itimer.c timers: split process wide cpu clocks/timers 2009-02-05 13:04:33 +01:00
kallsyms.c Ksplice: Add functions for walking kallsyms symbols 2009-03-31 13:05:32 +10:30
Kconfig.freezer
Kconfig.hz
Kconfig.preempt rcu: provide RCU options on non-preempt architectures too 2008-12-25 09:31:28 +01:00
kexec.c kexec: vmcoreinfo_data[] can become static 2009-04-02 19:05:04 -07:00
kfifo.c
kgdb.c sysrq, intel_fb: fix sysrq g collision 2009-05-15 07:56:24 -05:00
kmod.c module: create a request_module_nowait() 2009-03-31 13:05:35 +10:30
kprobes.c kprobes: fix to use text_mutex around arm/disarm kprobe 2009-05-08 16:23:48 -07:00
ksysfs.c kernel/ksysfs.c:fix dependence on CONFIG_NET 2009-01-06 10:44:31 -08:00
kthread.c tracing/events: move trace point headers into include/trace/events 2009-04-14 22:05:43 -04:00
latencytop.c sched, latencytop: incorporate review feedback from Andrew Morton 2009-02-11 10:18:04 +01:00
lockdep_internals.h lockdep: get_user_chars() redo 2009-02-14 23:28:22 +01:00
lockdep_proc.c lockstat: warn about disabled lock debugging 2009-02-14 23:28:28 +01:00
lockdep_states.h lockdep: move state bit definitions around 2009-02-14 23:27:59 +01:00
lockdep.c Merge branch 'linus' into tracing/core 2009-05-07 11:17:34 +02:00
Makefile Merge commit 'v2.6.30-rc3' into tracing/hw-branch-tracing 2009-04-24 10:11:23 +02:00
marker.c markers/tracpoints: fix non-modular build 2008-11-16 09:52:03 +01:00
module.c ftrace: use module notifier for function tracer 2009-04-17 16:59:15 +02:00
mutex-debug.c mutex: implement adaptive spinning 2009-01-14 18:09:02 +01:00
mutex-debug.h mutex: implement adaptive spinning 2009-01-14 18:09:02 +01:00
mutex.c mutex: have non-spinning mutexes on s390 by default 2009-04-09 19:28:24 +02:00
mutex.h mutex: implement adaptive spinning 2009-01-14 18:09:02 +01:00
notifier.c Merge commit 'v2.6.28-rc6' into core/debug 2008-11-26 08:22:50 +01:00
ns_cgroup.c cgroups: relax ns_can_attach checks to allow attaching to grandchild cgroups 2009-04-02 19:04:53 -07:00
nsproxy.c User namespaces: set of cleanups (v2) 2008-11-24 18:57:41 -05:00
panic.c Eliminate thousands of warnings with gcc 3.2 build 2009-05-06 16:36:09 -07:00
params.c param: fix charp parameters set via sysfs 2009-03-31 13:05:30 +10:30
pid_namespace.c signals: zap_pid_ns_process() should use force_sig() 2009-04-02 19:04:58 -07:00
pid.c pids: refactor vnr/nr_ns helpers to make them safe 2009-04-02 19:05:02 -07:00
pm_qos_params.c
posix-cpu-timers.c kernel/posix-cpu-timers.c: fix sparse warning 2009-04-30 08:08:31 +02:00
posix-timers.c [CVE-2009-0029] System call wrappers part 05 2009-01-14 14:15:20 +01:00
printk.c Merge branch 'printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 10:23:25 -07:00
profile.c profiling: fix broken profiling regression 2009-02-10 00:50:37 +01:00
ptrace.c Merge branch 'tracing/hw-branch-tracing' into tracing/core 2009-05-07 13:36:22 +02:00
rcuclassic.c kmemtrace, rcu: fix linux/rcutree.h and linux/rcuclassic.h dependencies 2009-04-03 12:23:02 +02:00
rcupdate.c RCU: Don't try and predeclare inline funcs as it upsets some versions of gcc 2009-04-15 13:55:14 -07:00
rcupreempt_trace.c "Tree RCU": scalable classic RCU implementation 2008-12-18 21:56:04 +01:00
rcupreempt.c kmemtrace, rcu: fix rcupreempt.c data structure dependencies 2009-04-03 12:23:04 +02:00
rcutorture.c cpumask: convert rcutorture.c 2009-03-30 22:05:16 +10:30
rcutree_trace.c rcu: Make hierarchical RCU less IPI-happy 2009-04-14 11:31:50 +02:00
rcutree.c rcu: Make hierarchical RCU less IPI-happy 2009-04-14 11:31:50 +02:00
rcutree.h kmemtrace, rcu: fix rcu_tree_trace.c data structure dependencies 2009-04-03 12:23:03 +02:00
relay.c Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-05 11:04:19 -07:00
res_counter.c memcg: memory cgroup resource counters for hierarchy 2009-01-08 08:31:05 -08:00
resource.c Remove 'recurse into child resources' logic from 'reserve_region_with_split()' 2009-04-18 21:44:24 -07:00
rtmutex_common.h
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c
rtmutex.h
rwsem.c
sched_clock.c Merge branch 'tracing/core-v2' into tracing-for-linus 2009-04-02 00:49:02 +02:00
sched_cpupri.c sched_rt: don't allocate cpumask in fastpath 2009-04-01 13:24:51 +02:00
sched_cpupri.h cpumask: remove cpumask_t from core 2009-03-30 22:05:17 +10:30
sched_debug.c sched: remove unused fields from struct rq 2009-03-24 23:16:51 +01:00
sched_fair.c Merge branch 'sched/urgent'; commit 'v2.6.29-rc5' into sched/core 2009-02-15 21:15:16 +01:00
sched_features.h Merge branch 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-03-30 17:17:35 -07:00
sched_idletask.c
sched_rt.c Merge commit 'v2.6.30-rc1' into sched/urgent 2009-04-08 17:26:00 +02:00
sched_stats.h sched: remove unused fields from struct rq 2009-03-24 23:16:51 +01:00
sched.c Merge branch 'tracing/hw-branch-tracing' into tracing/core 2009-05-07 13:36:22 +02:00
seccomp.c x86-64: seccomp: fix 32/64 syscall hole 2009-03-02 15:41:30 -08:00
semaphore.c
signal.c tracing/events: move trace point headers into include/trace/events 2009-04-14 22:05:43 -04:00
slow-work.c Delete slow-work timers properly 2009-04-24 07:47:59 -07:00
smp.c generic-ipi: eliminate WARN_ON()s during oops/panic 2009-03-13 10:47:34 +01:00
softirq.c Merge branch 'linus' into tracing/core 2009-05-07 11:17:34 +02:00
softlockup.c softlockup: decouple hung tasks check from softlockup detection 2009-01-16 14:06:04 +01:00
spinlock.c Allow rwlocks to re-enable interrupts 2009-04-02 19:05:11 -07:00
srcu.c
stacktrace.c stacktrace: provide save_stack_trace_tsk() weak alias 2008-12-25 11:44:43 +01:00
stop_machine.c cpumask: remove cpumask_t from core 2009-03-30 22:05:17 +10:30
sys_ni.c [CVE-2009-0029] Make sys_syslog a conditional system call 2009-01-14 14:15:16 +01:00
sys.c kernel/sys.c: clean up sys_shutdown exit path 2009-04-13 15:04:32 -07:00
sysctl_check.c net: add ARP notify option for devices 2009-02-01 01:04:33 -08:00
sysctl.c Revert "mm: add /proc controls for pdflush threads" 2009-05-15 11:32:24 +02:00
taskstats.c cpumask: convert rest of files in kernel/ 2009-01-01 10:12:28 +10:30
test_kprobes.c kprobes: add tests for register_kprobes 2009-01-06 15:59:20 -08:00
time.c [CVE-2009-0029] System call wrappers part 01 2009-01-14 14:15:18 +01:00
timeconst.pl
timer.c Merge branches 'core-fixes-for-linus', 'irq-fixes-for-linus' and 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-04-09 10:35:30 -07:00
tracepoint.c tracepoints: dont update zero-sized tracepoint sections 2009-03-18 19:55:00 +01:00
tsacct.c Fix fixpoint divide exception in acct_update_integrals 2009-03-09 08:13:35 -07:00
uid16.c [CVE-2009-0029] System call wrappers part 19 2009-01-14 14:15:26 +01:00
up.c smp_call_function_single(): be slightly less stupid, fix #2 2009-01-12 16:04:37 +01:00
user_namespace.c Fix recursive lock in free_uid()/free_user_ns() 2009-02-27 16:26:21 -08:00
user.c Merge branch 'master' into next 2009-03-24 10:52:46 +11:00
utsname_sysctl.c proc_sysctl: use CONFIG_PROC_SYSCTL around ipc and utsname proc_handlers 2009-04-02 19:05:01 -07:00
utsname.c
wait.c wait: prevent exclusive waiter starvation 2009-02-05 12:56:48 -08:00
workqueue.c work_on_cpu(): rewrite it to create a kernel thread on demand 2009-04-09 09:50:37 +09:30