This is a note to let you know that I've just added the patch titled
ring-buffer: Have the shortest_full queue be the shortest not longest
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ring-buffer-have-the-shortest_full-queue-be-the-shortest-not-longest.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3b19d614b61b93a131f463817e08219c9ce1fee3 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
Date: Tue, 27 Sep 2022 19:15:24 -0400
Subject: ring-buffer: Have the shortest_full queue be the shortest not longest
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
@@ -888,7 +888,7 @@ 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 &&
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are
queue-5.10/ring-buffer-have-the-shortest_full-queue-be-the-shortest-not-longest.patch
queue-5.10/ring-buffer-add-ring_buffer_wake_waiters.patch
queue-5.10/ring-buffer-fix-race-between-reset-page-and-reading-page.patch
queue-5.10/tracing-disable-interrupt-or-preemption-before-acquiring-arch_spinlock_t.patch
queue-5.10/ring-buffer-allow-splice-to-read-previous-partially-read-pages.patch
queue-5.10/ring-buffer-check-pending-waiters-when-doing-wake-ups-as-well.patch
queue-5.10/ftrace-properly-unset-ftrace_hash_fl_mod.patch
