diff options
| author |   Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2016-01-13 15:48:54 -0500 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2016-01-14 09:28:19 -0500 |
| commit | 7717c6be699975f6733d278b13b7c4295d73caf6 (patch) | |
| tree | 93de22146f1bba873c57d0d98b232c75b0a3727f /kernel/trace/trace.c | |
| parent | Linux 4.4 (diff) | |
| download | linux-dev-7717c6be699975f6733d278b13b7c4295d73caf6.tar.xz linux-dev-7717c6be699975f6733d278b13b7c4295d73caf6.zip | |
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: 73dddbb57bb0 "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>
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 87fb9801bd9e..d9293402ee68 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1751,7 +1751,7 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, { __buffer_unlock_commit(buffer, event); - ftrace_trace_stack(tr, buffer, flags, 6, pc, regs); + ftrace_trace_stack(tr, buffer, flags, 0, pc, regs); ftrace_trace_userstack(buffer, flags, pc); } EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit_regs); |