diff options
| author | pengdonglin <pengdonglin@xiaomi.com> | 2025-05-12 17:42:46 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-22 14:31:52 +0200 |
| commit | 42b6e6797618f813a57feb8fb8419236d15084ed (patch) | |
| tree | 3204914d56a96dd3b0984e892d6748dea117ce4c | |
| parent | 2a0fe3cb352beb41bb8999f2e61970518fe69244 (diff) | |
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>
| -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 df56f9b76010..eb6bebf1f1c7 100644 --- a/kernel/trace/trace_functions.c +++ b/kernel/trace/trace_functions.c @@ -597,11 +597,7 @@ 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 |