From: Julia Cartwright <julia@xxxxxx>
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@xxxxxxxxxxxxxxx
Signed-off-by: Julia Cartwright <julia@xxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
(cherry picked from commit afa4c06b89a3c0fb7784ff900ccd707bef519cb7)
Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
---
include/linux/seqlock.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 4acd0e2fb5cb..efa234031230 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -338,6 +338,7 @@ repeat:
spin_unlock_wait(&sl->lock);
goto repeat;
}
+ smp_rmb();
return ret;
}
#endif
--
2.14.1
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