Commit 3b19d614 authored by Steven Rostedt (Google)'s avatar Steven Rostedt (Google)
Browse files

ring-buffer: Have the shortest_full queue be the shortest not longest 

The logic to know when the shortest waiters on the ring buffer should be
woken up or not has uses a less than instead of a greater than compare,
which causes the shortest_full to actually be the longest.

Link: https://lkml.kernel.org/r/20220927231823.718039222@goodmis.org



Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 2c2b0a78 ("ring-buffer: Add percentage of ring buffer full to wake up reader")
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent fa8f4a89

kernel/trace/ring_buffer.c

+1 −1
Original line number Diff line number Diff line
@@ -1011,7 +1011,7 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full) 
			nr_pages = cpu_buffer->nr_pages;

			dirty = ring_buffer_nr_dirty_pages(buffer, cpu);

			if (!cpu_buffer->shortest_full ||

			    cpu_buffer->shortest_full < full)

			    cpu_buffer->shortest_full > full)

				cpu_buffer->shortest_full = full;

			raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);

			if (!pagebusy &&