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authorRik van Riel <riel@redhat.com>2014-09-12 09:12:14 -0400
committerIngo Molnar <mingo@kernel.org>2014-09-19 12:35:16 +0200
commitef8ac06359ddf95431cf6bb04ad2b36fff562328 (patch)
treea7987f9ce983b4e12e26c92c140ef88a4cd7c838 /include/linux/seqlock.h
parent2ed903c5485bad0eafdd3d59ff993598736e4f31 (diff)
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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@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: prarit@redhat.com Cc: oleg@redhat.com Cc: sgruszka@redhat.com Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Stephen Boyd <sboyd@codeaurora.org> Cc: Trond Myklebust <trond.myklebust@primarydata.com> Link: http://lkml.kernel.org/r/1410527535-9814-2-git-send-email-riel@redhat.com [ Improved the readability of the code a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/seqlock.h')
-rw-r--r--include/linux/seqlock.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index cc359636cfa3..f5df8f687b4d 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 */