Messages in this thread Patch in this message | | | From | riel@redhat ... | Subject | [PATCH -tip 1/2] seqlock: add irqsave variant of read_seqbegin_or_lock | Date | Fri, 12 Sep 2014 09:12:14 -0400 |
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From: Rik van Riel <riel@redhat.com>
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> --- include/linux/seqlock.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index cc35963..4364cd3 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -456,4 +456,21 @@ 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 */ -- 1.9.3
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