On Sun, 10 Dec 2023 22:54:47 -0500
Steven Rostedt <rost...@goodmis.org> wrote:
> From: "Steven Rostedt (Google)" <rost...@goodmis.org>
>
> The snapshot buffer is to mimic the main buffer so that when a snapshot is
> needed, the snapshot and main buffer are swapped. When the snapshot buffer
> is allocated, it is set to the minimal size that the ring buffer may be at
> and still functional. When it is allocated it becomes the same size as the
> main ring buffer, and when the main ring buffer changes in size, it should
> do.
nit: There seems two "when the snapshot buffer is allocated" case, maybe latter
"it" means main buffer?
>
> Currently, the resize only updates the snapshot buffer if it's used by the
> current tracer (ie. the preemptirqsoff tracer). But it needs to be updated
> anytime it is allocated.
>
> When changing the size of the main buffer, instead of looking to see if
> the current tracer is utilizing the snapshot buffer, just check if it is
> allocated to know if it should be updated or not.
>
> Also fix typo in comment just above the code change.
>
Looks good to me.
Reviewed-by: Masami Hiramatsu (Google) <mhira...@kernel.org>
BTW, the historical naming leads this kind of issues.
Maybe we'd better to rename 'max_buffer' to 'snapshot_buffer'?
Thanks,
> Cc: sta...@vger.kernel.org
> Fixes: ad909e21bbe69 ("tracing: Add internal tracing_snapshot() functions")
> Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
> ---
> kernel/trace/trace.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index aa8f99f3e5de..6c79548f9574 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -6348,7 +6348,7 @@ static int __tracing_resize_ring_buffer(struct
> trace_array *tr,
> if (!tr->array_buffer.buffer)
> return 0;
>
> - /* Do not allow tracing while resizng ring buffer */
> + /* Do not allow tracing while resizing ring buffer */
> tracing_stop_tr(tr);
>
> ret = ring_buffer_resize(tr->array_buffer.buffer, size, cpu);
> @@ -6356,7 +6356,7 @@ static int __tracing_resize_ring_buffer(struct
> trace_array *tr,
> goto out_start;
>
> #ifdef CONFIG_TRACER_MAX_TRACE
> - if (!tr->current_trace->use_max_tr)
> + if (!tr->allocated_snapshot)
> goto out;
>
> ret = ring_buffer_resize(tr->max_buffer.buffer, size, cpu);
> --
> 2.42.0
>
--
Masami Hiramatsu (Google) <mhira...@kernel.org>
