[PATCH 5.15 107/530] ring-buffer: Have the shortest_full queue be the shortest not longest

[Greg Kroah-Hartman]

From: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>

commit 3b19d614b61b93a131f463817e08219c9ce1fee3 upstream.

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@xxxxxxxxxxx

Cc: stable@xxxxxxxxxxxxxxx
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Fixes: 2c2b0a78b3739 ("ring-buffer: Add percentage of ring buffer full to wake up reader")
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 kernel/trace/ring_buffer.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -975,7 +975,7 @@ int ring_buffer_wait(struct trace_buffer
 			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 &&