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7717c6be69
linux/kernel/trace
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Steven Rostedt (Red Hat) 7717c6be69 tracing: Fix stacktrace skip depth in trace_buffer_unlock_commit_regs() 
While cleaning the stacktrace code I unintentially changed the skip depth of
trace_buffer_unlock_commit_regs() from 0 to 6. kprobes uses this function,
and with skipping 6 call backs, it can easily produce no stack.

Here's how I tested it:

 # echo 'p:ext4_sync_fs ext4_sync_fs ' > /sys/kernel/debug/tracing/kprobe_events
 # echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable
 # cat /sys/kernel/debug/trace
            sync-2394  [005]   502.457060: ext4_sync_fs: (ffffffff81317650)
            sync-2394  [005]   502.457063: kernel_stack:         <stack trace>
            sync-2394  [005]   502.457086: ext4_sync_fs: (ffffffff81317650)
            sync-2394  [005]   502.457087: kernel_stack:         <stack trace>
            sync-2394  [005]   502.457091: ext4_sync_fs: (ffffffff81317650)

After putting back the skip stack to zero, we have:

            sync-2270  [000]   748.052693: ext4_sync_fs: (ffffffff81317650)
            sync-2270  [000]   748.052695: kernel_stack:         <stack trace>
 => iterate_supers (ffffffff8126412e)
 => sys_sync (ffffffff8129c4b6)
 => entry_SYSCALL_64_fastpath (ffffffff8181f0b2)
            sync-2270  [000]   748.053017: ext4_sync_fs: (ffffffff81317650)
            sync-2270  [000]   748.053019: kernel_stack:         <stack trace>
 => iterate_supers (ffffffff8126412e)
 => sys_sync (ffffffff8129c4b6)
 => entry_SYSCALL_64_fastpath (ffffffff8181f0b2)
            sync-2270  [000]   748.053381: ext4_sync_fs: (ffffffff81317650)
            sync-2270  [000]   748.053383: kernel_stack:         <stack trace>
 => iterate_supers (ffffffff8126412e)
 => sys_sync (ffffffff8129c4b6)
 => entry_SYSCALL_64_fastpath (ffffffff8181f0b2)

Cc: stable@vger.kernel.org # v4.4+
Fixes: 73dddbb57b "tracing: Only create stacktrace option when STACKTRACE is configured"
Reported-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Tested-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-01-14 09:28:19 -05:00
..
blktrace.c Most of the changes are clean ups and small fixes. Some of them have 2015-11-06 13:30:20 -08:00
bpf_trace.c bpf: make tracing helpers gpl only 2015-10-26 21:53:34 -07:00
ftrace.c Most of the changes are clean ups and small fixes. Some of them have 2015-11-06 13:30:20 -08:00
Kconfig Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-11-10 18:11:41 -08:00
Makefile bpf: Fix the build on BPF_SYSCALL=y && !CONFIG_TRACING kernels, make it more configurable 2015-04-02 16:28:06 +02:00
power-traces.c PM / sleep: export suspend_resume trace event 2015-01-30 02:10:41 +01:00
ring_buffer_benchmark.c ring_buffer: Remove unneeded smp_wmb() before wakeup of reader benchmark 2015-11-03 16:19:02 -05:00
ring_buffer.c ring-buffer: Put back the length if crossed page with add_timestamp 2015-11-24 09:27:25 -05:00
rpm-traces.c
trace_benchmark.c tracing: Only benchmark the time tracepoints take if tracing is on 2015-11-02 13:34:58 -05:00
trace_benchmark.h tracing: Add tracepoint benchmark tracepoint 2014-05-29 22:49:54 -04:00
trace_branch.c tracing: Remove {start,stop}_branch_trace 2015-10-21 10:10:09 -04:00
trace_clock.c tracing: Export tracing clock functions 2015-05-12 15:56:57 -04:00
trace_entries.h tracing: %pF is only for function pointers 2015-03-25 08:57:22 -04:00
trace_event_perf.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
trace_events_filter_test.h
trace_events_filter.c tracing: is_legal_op() can return boolean 2015-11-02 14:26:51 -05:00
trace_events_trigger.c tracing: Rename ftrace_raw_##call event structures to trace_event_raw_##call 2015-05-13 21:48:40 -04:00
trace_events.c tracing: Add sched_wakeup_new and sched_waking tracepoints for pid filter 2015-12-01 16:08:05 -05:00
trace_export.c tracing: ftrace_event_is_function() can return boolean 2015-11-02 14:28:05 -05:00
trace_functions_graph.c tracing: Remove unused ftrace_cpu_disabled per cpu variable 2015-11-07 13:25:14 -05:00
trace_functions.c tracing/trivial: Fix typos and make an int into a bool 2014-11-20 10:05:36 -05:00
trace_irqsoff.c tracing: report_latency() in trace_irqsoff.c can return boolean 2015-11-02 14:20:19 -05:00
trace_kdb.c tracing: Move trace_flags from global to a trace_array field 2015-09-30 15:22:55 -04:00
trace_kprobe.c lib: introduce strncpy_from_unsafe() 2015-08-28 16:27:27 -07:00
trace_mmiotrace.c tracing: Pass trace_array into trace_buffer_unlock_commit() 2015-09-25 17:38:44 -04:00
trace_nop.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_output.c tracing: Move trace_flags from global to a trace_array field 2015-09-30 15:22:55 -04:00
trace_output.h tracing: Turn seq_print_user_ip() into a static function 2015-09-28 10:16:12 -04:00
trace_printk.c tracing: Fix setting of start_index in find_next() 2016-01-04 15:22:47 -05:00
trace_probe.c trace: Don't use __weak in header files 2015-03-25 08:57:23 -04:00
trace_probe.h kernel/trace_probe: is_good_name can be boolean 2015-09-22 13:11:30 -04:00
trace_sched_switch.c sched/core: Fix trace_sched_switch() 2015-10-06 17:08:15 +02:00
trace_sched_wakeup.c Most of the changes are clean ups and small fixes. Some of them have 2015-11-06 13:30:20 -08:00
trace_selftest_dynamic.c
trace_selftest.c Seems that Peter Zijlstra added a new check that is making old 2014-10-12 07:28:55 -04:00
trace_seq.c tracing: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
trace_stack.c Most of the changes are clean ups and small fixes. Some of them have 2015-11-06 13:30:20 -08:00
trace_stat.c tracing: Convert the tracing facility over to use tracefs 2015-02-03 12:48:41 -05:00
trace_stat.h
trace_syscalls.c tracing: Move trace_flags from global to a trace_array field 2015-09-30 15:22:55 -04:00
trace_uprobe.c tracing/uprobes: Do not print '0x (null)' when offset is 0 2015-08-26 10:43:01 -03:00
trace.c tracing: Fix stacktrace skip depth in trace_buffer_unlock_commit_regs() 2016-01-14 09:28:19 -05:00
trace.h tracing: Remove unused ftrace_cpu_disabled per cpu variable 2015-11-07 13:25:14 -05:00