lkml.org 
[lkml]   [2018]   [Sep]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH RT 07/22] seqlock: provide the same ordering semantics as mainline
4.14.63-rt41-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Julia Cartwright <julia@ni.com>

[ Upstream commit afa4c06b89a3c0fb7784ff900ccd707bef519cb7 ]

The mainline implementation of read_seqbegin() orders prior loads w.r.t.
the read-side critical section. Fixup the RT writer-boosting
implementation to provide the same guarantee.

Also, while we're here, update the usage of ACCESS_ONCE() to use
READ_ONCE().

Fixes: e69f15cf77c23 ("seqlock: Prevent rt starvation")
Cc: stable-rt@vger.kernel.org
Signed-off-by: Julia Cartwright <julia@ni.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
include/linux/seqlock.h | 1 +
1 file changed, 1 insertion(+)

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index a59751276b94..107079a2d7ed 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -462,6 +462,7 @@ static inline unsigned read_seqbegin(seqlock_t *sl)
spin_unlock_wait(&sl->lock);
goto repeat;
}
+ smp_rmb();
return ret;
}
#endif
--
2.18.0

\
 
 \ /
  Last update: 2018-09-05 14:31    [W:0.179 / U:6.324 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site