Re: [RFC PATCH v5 2/3] trace: integrate stackmap into ftrace stack recording path

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Commit message claims ring buffer is reset, but code explicitly avoids it, leaving an unused exported function.
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commit 1c84dfe93f15f95df9476204e9b82e02328ae613
Author: Pengfei Li <lipengfei28@xiaomi.com>

trace: integrate stackmap into ftrace stack recording path

Add TRACE_STACK_ID event type and integrate ftrace_stackmap into
__ftrace_trace_stack(). When the 'stackmap' trace option is enabled,
the stack recording path stores a 4-byte stack_id in the ring buffer
instead of the full stack trace.

>     - ftrace_stackmap_create() takes the owning trace_array so the
>       stackmap can later clear that trace_array's buffers during reset.

[Severity: Medium]
The commit message claims that the stackmap clears the trace_array's buffers
during reset, but the actual stackmap implementation avoids doing this.

Could the commit message be updated to reflect that the buffers are not
cleared?

> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 18710c190c924..0210dc597f77d 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
[ ... ]
> @@ -1562,7 +1564,7 @@ void tracing_reset_online_cpus(struct array_buffer *buf)
>  	ring_buffer_record_enable(buffer);
>  }
>  
> -static void tracing_reset_all_cpus(struct array_buffer *buf)
> +void tracing_reset_all_cpus(struct array_buffer *buf)
>  {
>  	struct trace_buffer *buffer = buf->buffer;
>  
[ ... ]
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 80fe152af1dd8..95db43bfc747a 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
[ ... ]
> @@ -689,6 +695,7 @@ extern int tracing_disabled;
>  int tracer_init(struct tracer *t, struct trace_array *tr);
>  int tracing_is_enabled(void);
>  void tracing_reset_online_cpus(struct array_buffer *buf);
> +void tracing_reset_all_cpus(struct array_buffer *buf);
>  void tracing_reset_all_online_cpus(void);

[Severity: Medium]
Does this code unnecessarily export tracing_reset_all_cpus() outside of
trace.c?

Since the stackmap reset functionality does not actually clear the ring
buffers, it seems this function is left completely unused externally.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260902064242.28606-1-lipengfei28@xiaomi.com?part=2