From: Steven Rostedt Date: Fri, 14 Feb 2025 17:35:12 +0000 (-0500) Subject: ring-buffer: Update pages_touched to reflect persistent buffer content X-Git-Tag: v6.14-rc3~13^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=97937834ae876f29565415ab15f1284666dc6be3;p=thirdparty%2Fkernel%2Fstable.git ring-buffer: Update pages_touched to reflect persistent buffer content The pages_touched field represents the number of subbuffers in the ring buffer that have content that can be read. This is used in accounting of "dirty_pages" and "buffer_percent" to allow the user to wait for the buffer to be filled to a certain amount before it reads the buffer in blocking mode. The persistent buffer never updated this value so it was set to zero, and this accounting would take it as it had no content. This would cause user space to wait for content even though there's enough content in the ring buffer that satisfies the buffer_percent. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Vincent Donnefort Link: https://lore.kernel.org/20250214123512.0631436e@gandalf.local.home Fixes: 5f3b6e839f3ce ("ring-buffer: Validate boot range memory events") Signed-off-by: Steven Rostedt (Google) --- diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0419d41a20604..bb6089c2951e5 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1850,6 +1850,11 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->cpu); goto invalid; } + + /* If the buffer has content, update pages_touched */ + if (ret) + local_inc(&cpu_buffer->pages_touched); + entries += ret; entry_bytes += local_read(&head_page->page->commit); local_set(&cpu_buffer->head_page->entries, ret);