On Wed, 20 May 2026 14:49:45 -0400 Steven Rostedt <[email protected]> wrote:
> From: Steven Rostedt <[email protected]> > > On bootup if the persistent ring buffer finds an invalid sub-buffer, it > only invalidates the invalid sub-buffer and continues. Several sub-buffers > may be invalid and this can cause the iterator to loop more than 3 times > looking for a new event. If that happens, then it returns NULL. Having a > NULL return early can confuse the iterator looking for the next event, and > may show events out of order. > > Have the same logic for the consuming read for the iterator that will > allow the loop to find the next event to happen the number of sub-buffers > and not just 3. > > Fixes: **TBD** ring-buffer: Skip invalid sub-buffers when validating > persistent ring buffer > Signed-off-by: Steven Rostedt <[email protected]> Should we merge this into the original one? Anyway, this looks good to me. Thanks, > --- > kernel/trace/ring_buffer.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index c6c2f92bfc24..bda53a2d2159 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -6103,12 +6103,14 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) > struct ring_buffer_per_cpu *cpu_buffer; > struct ring_buffer_event *event; > int nr_loops = 0; > + int max_loops; > > if (ts) > *ts = 0; > > cpu_buffer = iter->cpu_buffer; > buffer = cpu_buffer->buffer; > + max_loops = cpu_buffer->ring_meta ? cpu_buffer->nr_pages : 3; > > /* > * Check if someone performed a consuming read to the buffer > @@ -6131,7 +6133,7 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) > * the ring buffer with an active write as the consumer is. > * Do not warn if the three failures is reached. > */ > - if (++nr_loops > 3) > + if (++nr_loops > max_loops) > return NULL; > > if (rb_per_cpu_empty(cpu_buffer)) > -- > 2.53.0 > > -- Masami Hiramatsu (Google) <[email protected]>
