linux/kernel
Paul Burton b81b3e959a tracing: Simplify & fix saved_tgids logic
The tgid_map array records a mapping from pid to tgid, where the index
of an entry within the array is the pid & the value stored at that index
is the tgid.

The saved_tgids_next() function iterates over pointers into the tgid_map
array & dereferences the pointers which results in the tgid, but then it
passes that dereferenced value to trace_find_tgid() which treats it as a
pid & does a further lookup within the tgid_map array. It seems likely
that the intent here was to skip over entries in tgid_map for which the
recorded tgid is zero, but instead we end up skipping over entries for
which the thread group leader hasn't yet had its own tgid recorded in
tgid_map.

A minimal fix would be to remove the call to trace_find_tgid, turning:

  if (trace_find_tgid(*ptr))

into:

  if (*ptr)

..but it seems like this logic can be much simpler if we simply let
seq_read() iterate over the whole tgid_map array & filter out empty
entries by returning SEQ_SKIP from saved_tgids_show(). Here we take that
approach, removing the incorrect logic here entirely.

Link: https://lkml.kernel.org/r/20210630003406.4013668-1-paulburton@google.com

Fixes: d914ba37d7 ("tracing: Add support for recording tgid of tasks")
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Paul Burton <paulburton@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-06-30 09:19:14 -04:00
..
bpf bpf, lockdown, audit: Fix buggy SELinux lockdown permission checks 2021-06-02 21:59:22 +02:00
cgroup cgroup: fix spelling mistakes 2021-05-24 12:45:26 -04:00
configs drivers/char: remove /dev/kmem for good 2021-05-07 00:26:34 -07:00
debug printk changes for 5.13 2021-04-27 18:09:44 -07:00
dma Merge branch 'stable/for-linus-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb 2021-05-04 10:58:49 -07:00
entry A trivial cleanup of typo fixes. 2021-04-26 09:41:15 -07:00
events Merge branch 'for-v5.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2021-05-21 06:12:52 -10:00
gcov gcov: clang: drop support for clang-10 and older 2021-05-07 00:26:32 -07:00
irq gpio updates for v5.13 2021-05-05 12:39:29 -07:00
kcsan kcsan: Fix debugfs initcall return type 2021-05-18 10:58:02 -07:00
livepatch Livepatching changes for 5.13 2021-04-27 18:14:38 -07:00
locking locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal 2021-05-18 12:53:51 +02:00
power PM: sleep: fix typos in comments 2021-04-08 19:37:21 +02:00
printk kernel/printk.c: Fixed mundane typos 2021-03-30 15:34:17 +02:00
rcu Merge branches 'bitmaprange.2021.03.08a', 'fixes.2021.03.15a', 'kvfree_rcu.2021.03.08a', 'mmdumpobj.2021.03.08a', 'nocb.2021.03.15a', 'poll.2021.03.24a', 'rt.2021.03.08a', 'tasks.2021.03.08a', 'torture.2021.03.08a' and 'torturescript.2021.03.22a' into HEAD 2021-03-24 17:20:18 -07:00
sched sched/fair: Fix clearing of has_idle_cores flag in select_idle_cpu() 2021-05-12 10:41:28 +02:00
time alarmtimer: Check RTC features instead of ops 2021-05-11 21:28:04 +02:00
trace tracing: Simplify & fix saved_tgids logic 2021-06-30 09:19:14 -04:00
.gitignore .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
acct.c kernel/acct.c: use #elif instead of #end and #elif 2020-12-15 22:46:15 -08:00
async.c kernel/async.c: remove async_unregister_domain() 2021-05-07 00:26:33 -07:00
audit_fsnotify.c audit_alloc_mark(): don't open-code ERR_CAST() 2021-02-23 10:25:27 -05:00
audit_tree.c fsnotify: generalize handle_inode_event() 2020-12-03 14:58:35 +01:00
audit_watch.c fsnotify: generalize handle_inode_event() 2020-12-03 14:58:35 +01:00
audit.c lsm: separate security_task_getsecid() into subjective and objective variants 2021-03-22 15:23:32 -04:00
audit.h audit: avoid -Wempty-body warning 2021-03-24 12:11:48 -04:00
auditfilter.c lsm: separate security_task_getsecid() into subjective and objective variants 2021-03-22 15:23:32 -04:00
auditsc.c audit/stable-5.13 PR 20210426 2021-04-27 13:50:58 -07:00
backtracetest.c
bounds.c
capability.c capability: handle idmapped mounts 2021-01-24 14:27:16 +01:00
cfi.c add support for Clang CFI 2021-04-08 16:04:20 -07:00
compat.c
configs.c
context_tracking.c
cpu_pm.c
cpu.c cpumask/hotplug: Fix cpu_dying() state tracking 2021-04-21 13:55:43 +02:00
crash_core.c kdump: append uts_namespace.name offset to VMCOREINFO 2020-12-15 22:46:18 -08:00
crash_dump.c
cred.c kernel/cred.c: make init_groups static 2021-05-06 19:24:11 -07:00
delayacct.c
dma.c
exec_domain.c
exit.c do_wait: make PIDTYPE_PID case O(1) instead of O(n) 2021-05-06 19:24:13 -07:00
extable.c
fail_function.c fault-injection: handle EI_ETYPE_TRUE 2020-12-15 22:46:19 -08:00
fork.c kernel/fork.c: fix typos 2021-05-06 19:24:13 -07:00
freezer.c Revert "kernel: freezer should treat PF_IO_WORKER like PF_KTHREAD for freezing" 2021-03-27 14:09:10 -06:00
futex.c futex: Make syscall entry points less convoluted 2021-05-06 20:19:04 +02:00
gen_kheaders.sh kbuild: redo fake deps at include/config/*.h 2021-04-25 05:26:10 +09:00
groups.c groups: simplify struct group_info allocation 2021-02-26 09:41:03 -08:00
hung_task.c
iomem.c
irq_work.c irq_work: record irq_work_queue() call stack 2021-04-30 11:20:42 -07:00
jump_label.c static_call: Fix static_call_update() sanity check 2021-03-19 13:16:44 +01:00
kallsyms.c kallsyms: strip ThinLTO hashes from static functions 2021-04-08 16:04:21 -07:00
kcmp.c Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:36:48 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt preempt: Introduce CONFIG_PREEMPT_DYNAMIC 2021-02-17 14:12:24 +01:00
kcov.c kernel: make kcov_common_handle consider the current context 2020-11-02 18:00:20 -08:00
kexec_core.c kexec: dump kmessage before machine_kexec 2021-05-07 00:26:32 -07:00
kexec_elf.c
kexec_file.c kernel: kexec_file: fix error return code of kexec_calculate_store_digests() 2021-05-07 00:26:32 -07:00
kexec_internal.h kexec: move machine_kexec_post_load() to public interface 2021-02-22 12:33:26 +00:00
kexec.c
kheaders.c
kmod.c modules: add CONFIG_MODPROBE_PATH 2021-05-07 00:26:33 -07:00
kprobes.c kprobes: Fix to delay the kprobes jump optimization 2021-02-19 14:57:12 -05:00
ksysfs.c
kthread.c Scheduler updates for this cycle are: 2021-04-28 13:33:57 -07:00
latencytop.c
Makefile kbuild: update config_data.gz only when the content of .config is changed 2021-05-02 00:43:35 +09:00
module_signature.c module: harden ELF info handling 2021-01-19 10:24:45 +01:00
module_signing.c module: harden ELF info handling 2021-01-19 10:24:45 +01:00
module-internal.h
module.c module: check for exit sections in layout_sections() instead of module_init_section() 2021-05-17 09:48:24 +02:00
notifier.c
nsproxy.c fixes-v5.11 2020-12-14 16:40:27 -08:00
padata.c
panic.c panic: don't dump stack twice on warn 2020-11-14 11:26:04 -08:00
params.c Modules updates for v5.11 2020-12-17 13:01:31 -08:00
pid_namespace.c fixes-v5.11 2020-12-14 16:40:27 -08:00
pid.c Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:36:48 -08:00
profile.c kernel: Initialize cpumask before parsing 2021-04-10 13:35:54 +02:00
ptrace.c ptrace: make ptrace() fail if the tracee changed its pid unexpectedly 2021-05-12 10:45:22 -07:00
range.c
reboot.c Revert "PM: ACPI: reboot: Use S5 for reboot" 2021-03-18 16:58:02 +01:00
regset.c
relay.c relay: allow the use of const callback structs 2020-12-15 22:46:18 -08:00
resource_kunit.c resource: provide meaningful MODULE_LICENSE() in test suite 2020-11-25 18:52:35 +01:00
resource.c kernel/resource: fix return code check in __request_free_mem_region 2021-05-14 19:41:32 -07:00
rseq.c rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs() 2021-04-14 18:04:09 +02:00
scftorture.c scftorture: Add debug output for wrong-CPU warning 2021-01-04 13:53:41 -08:00
scs.c scs: switch to vmapped shadow stacks 2020-12-01 10:30:28 +00:00
seccomp.c seccomp: Refactor notification handler to prepare for new semantics 2021-05-29 11:13:27 -07:00
signal.c Merge branch 'for-v5.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2021-05-21 06:12:52 -10:00
smp.c smp: Fix smp_call_function_single_async prototype 2021-05-06 15:33:49 +02:00
smpboot.c kthread: Extract KTHREAD_IS_PER_CPU 2021-01-22 15:09:42 +01:00
smpboot.h
softirq.c RCU changes for this cycle were: 2021-04-28 12:00:13 -07:00
stackleak.c
stacktrace.c
static_call.c static_call: Fix unused variable warn w/o MODULE 2021-04-09 13:22:12 +02:00
stop_machine.c stop_machine: Add caller debug info to queue_stop_cpus_work 2021-03-23 16:01:58 +01:00
sys_ni.c Add Landlock, a new LSM from Mickaël Salaün <mic@linux.microsoft.com> 2021-05-01 18:50:44 -07:00
sys.c kernel/sys.c: fix typo 2021-05-07 00:26:34 -07:00
sysctl-test.c
sysctl.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2021-05-11 16:05:56 -07:00
task_work.c kasan: record task_work_add() call stack 2021-04-30 11:20:42 -07:00
taskstats.c treewide: rename nla_strlcpy to nla_strscpy. 2020-11-16 08:08:54 -08:00
test_kprobes.c
torture.c torture: Replace torture_init_begin string with %s 2021-03-08 14:22:28 -08:00
tracepoint.c tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing 2021-06-29 11:51:25 -04:00
tsacct.c
ucount.c fanotify: configurable limits via sysfs 2021-03-16 16:49:31 +01:00
uid16.c
uid16.h
umh.c kernel/umh.c: fix some spelling mistakes 2021-05-07 00:26:34 -07:00
up.c A set of locking related fixes and updates: 2021-05-09 13:07:03 -07:00
user_namespace.c kernel/user_namespace.c: fix typos 2021-05-07 00:26:34 -07:00
user-return-notifier.c
user.c
usermode_driver.c bpf: Fix umd memory leak in copy_process() 2021-03-19 22:23:19 +01:00
utsname_sysctl.c
utsname.c
watch_queue.c watch_queue: rectify kernel-doc for init_watch() 2021-01-26 11:16:34 +00:00
watchdog_hld.c
watchdog.c watchdog: reliable handling of timestamps 2021-05-22 15:09:07 -10:00
workqueue_internal.h
workqueue.c wq: handle VM suspension in stall detection 2021-05-20 12:58:30 -04:00