This is a note to let you know that I've just added the patch titled
tracing: Wake up waiters when tracing is disabled
to the 5.15-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:
tracing-wake-up-waiters-when-tracing-is-disabled.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2b0fd9a59b7990c161fa1cb7b79edb22847c87c2 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
Date: Wed, 28 Sep 2022 18:22:20 -0400
Subject: tracing: Wake up waiters when tracing is disabled
From: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
commit 2b0fd9a59b7990c161fa1cb7b79edb22847c87c2 upstream.
When tracing is disabled, there's no reason that waiters should stay
waiting, wake them up, otherwise tasks get stuck when they should be
flushing the buffers.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: e30f53aad2202 ("tracing: Do not busy wait in buffer splice")
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8291,6 +8291,10 @@ tracing_buffers_splice_read(struct file
if (ret)
goto out;
+ /* No need to wait after waking up when tracing is off */
+ if (!tracer_tracing_is_on(iter->tr))
+ goto out;
+
/* Make sure we see the new wait_index */
smp_rmb();
if (wait_index != iter->wait_index)
@@ -9000,6 +9004,8 @@ rb_simple_write(struct file *filp, const
tracer_tracing_off(tr);
if (tr->current_trace->stop)
tr->current_trace->stop(tr);
+ /* Wake up any waiters */
+ ring_buffer_wake_waiters(buffer, RING_BUFFER_ALL_CPUS);
}
mutex_unlock(&trace_types_lock);
}
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are
queue-5.15/tracing-fix-reading-strings-from-synthetic-events.patch
queue-5.15/tracing-add-ioctl-to-force-ring-buffer-waiters-to-wake-up.patch
queue-5.15/ring-buffer-have-the-shortest_full-queue-be-the-shortest-not-longest.patch
queue-5.15/ring-buffer-add-ring_buffer_wake_waiters.patch
queue-5.15/tracing-move-duplicate-code-of-trace_kprobe-eprobe.c-into-header.patch
queue-5.15/tracing-add-fault-name-injection-to-kernel-probes.patch
queue-5.15/ring-buffer-fix-race-between-reset-page-and-reading-page.patch
queue-5.15/tracing-wake-up-ring-buffer-waiters-on-closing-of-the-file.patch
queue-5.15/tracing-disable-interrupt-or-preemption-before-acquiring-arch_spinlock_t.patch
queue-5.15/tracing-wake-up-waiters-when-tracing-is-disabled.patch
queue-5.15/ring-buffer-allow-splice-to-read-previous-partially-read-pages.patch
queue-5.15/ring-buffer-check-pending-waiters-when-doing-wake-ups-as-well.patch
queue-5.15/ftrace-properly-unset-ftrace_hash_fl_mod.patch
