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| author | pengdonglin <pengdonglin@xiaomi.com> | 2025-05-12 17:42:46 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-22 14:29:48 +0200 |
| commit | 589c9e66bd475be43625104cc24d6cbb77abb582 (patch) | |
| tree | 98b4ba25d753117db1db2bcc15df5455b3e8cb45 /kernel | |
| parent | 7d353da580c5f3deac2c61035aab4d720dc2d421 (diff) | |
| download | linux-589c9e66bd475be43625104cc24d6cbb77abb582.tar.gz linux-589c9e66bd475be43625104cc24d6cbb77abb582.tar.bz2 linux-589c9e66bd475be43625104cc24d6cbb77abb582.zip | |
ftrace: Fix preemption accounting for stacktrace filter command
commit 11aff32439df6ca5b3b891b43032faf88f4a6a29 upstream.
The preemption count of the stacktrace filter command to trace ksys_read
is consistently incorrect:
$ echo ksys_read:stacktrace > set_ftrace_filter
<...>-453 [004] ...1. 38.308956: <stack trace>
=> ksys_read
=> do_syscall_64
=> entry_SYSCALL_64_after_hwframe
The root cause is that the trace framework disables preemption when
invoking the filter command callback in function_trace_probe_call:
preempt_disable_notrace();
probe_ops->func(ip, parent_ip, probe_opsbe->tr, probe_ops, probe->data);
preempt_enable_notrace();
Use tracing_gen_ctx_dec() to account for the preempt_disable_notrace(),
which will output the correct preemption count:
$ echo ksys_read:stacktrace > set_ftrace_filter
<...>-410 [006] ..... 31.420396: <stack trace>
=> ksys_read
=> do_syscall_64
=> entry_SYSCALL_64_after_hwframe
Cc: stable@vger.kernel.org
Fixes: 36590c50b2d07 ("tracing: Merge irqflags + preempt counter.")
Link: https://lore.kernel.org/20250512094246.1167956-2-dolinux.peng@gmail.com
Signed-off-by: pengdonglin <dolinux.peng@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_functions.c | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c index fbbc3c719d2f..fbb6cf8dc047 100644 --- a/kernel/trace/trace_functions.c +++ b/kernel/trace/trace_functions.c @@ -574,11 +574,7 @@ ftrace_traceoff(unsigned long ip, unsigned long parent_ip, static __always_inline void trace_stack(struct trace_array *tr) { - unsigned int trace_ctx; - - trace_ctx = tracing_gen_ctx(); - - __trace_stack(tr, trace_ctx, FTRACE_STACK_SKIP); + __trace_stack(tr, tracing_gen_ctx_dec(), FTRACE_STACK_SKIP); } static void |