blob: 1068113c5fab8570de1b230575f1c2d0bae323ee (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
From: Scott Wood <swood@redhat.com>
Date: Fri, 4 Jan 2019 15:33:21 -0500
Subject: [PATCH 151/353] locking/rt-mutex: Flush block plug on __down_read()
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=e16669ece8894e9a9a0b506e37e957c05aafb084
__down_read() bypasses the rtmutex frontend to call
rt_mutex_slowlock_locked() directly, and thus it needs to call
blk_schedule_flush_flug() itself.
Cc: stable-rt@vger.kernel.org
Signed-off-by: Scott Wood <swood@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/locking/rwsem-rt.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/locking/rwsem-rt.c b/kernel/locking/rwsem-rt.c
index 660e22caf709..f518495bd6cc 100644
--- a/kernel/locking/rwsem-rt.c
+++ b/kernel/locking/rwsem-rt.c
@@ -1,5 +1,6 @@
/*
*/
+#include <linux/blkdev.h>
#include <linux/rwsem.h>
#include <linux/sched/debug.h>
#include <linux/sched/signal.h>
@@ -87,6 +88,14 @@ static int __sched __down_read_common(struct rw_semaphore *sem, int state)
if (__down_read_trylock(sem))
return 0;
+ /*
+ * If rt_mutex blocks, the function sched_submit_work will not call
+ * blk_schedule_flush_plug (because tsk_is_pi_blocked would be true).
+ * We must call blk_schedule_flush_plug here, if we don't call it,
+ * a deadlock in I/O may happen.
+ */
+ if (unlikely(blk_needs_flush_plug(current)))
+ blk_schedule_flush_plug(current);
might_sleep();
raw_spin_lock_irq(&m->wait_lock);
|
