Commit-ID: ef8ac06359ddf95431cf6bb04ad2b36fff562328
Gitweb: http://git.kernel.org/tip/ef8ac06359ddf95431cf6bb04ad2b36fff562328
Author: Rik van Riel <riel@xxxxxxxxxx>
AuthorDate: Fri, 12 Sep 2014 09:12:14 -0400
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 19 Sep 2014 12:35:16 +0200
seqlock: Add irqsave variant of read_seqbegin_or_lock()
There are cases where read_seqbegin_or_lock() needs to block irqs,
because the seqlock in question nests inside a lock that is also
be taken from irq context.
Add read_seqbegin_or_lock_irqsave() and done_seqretry_irqrestore(), which
are almost identical to read_seqbegin_or_lock() and done_seqretry().
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: prarit@xxxxxxxxxx
Cc: oleg@xxxxxxxxxx
Cc: sgruszka@xxxxxxxxxx
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1410527535-9814-2-git-send-email-riel@xxxxxxxxxx
[ Improved the readability of the code a bit. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/seqlock.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index cc35963..f5df8f6 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -456,4 +456,23 @@ read_sequnlock_excl_irqrestore(seqlock_t *sl, unsigned long flags)
spin_unlock_irqrestore(&sl->lock, flags);
}
+static inline unsigned long
+read_seqbegin_or_lock_irqsave(seqlock_t *lock, int *seq)
+{
+ unsigned long flags = 0;
+
+ if (!(*seq & 1)) /* Even */
+ *seq = read_seqbegin(lock);
+ else /* Odd */
+ read_seqlock_excl_irqsave(lock, flags);
+
+ return flags;
+}
+
+static inline void
+done_seqretry_irqrestore(seqlock_t *lock, int seq, unsigned long flags)
+{
+ if (seq & 1)
+ read_sequnlock_excl_irqrestore(lock, flags);
+}
#endif /* __LINUX_SEQLOCK_H */
--
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