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authorKalle Valo <kvalo@qca.qualcomm.com>2012-06-14 14:20:18 +0300
committerKalle Valo <kvalo@qca.qualcomm.com>2012-06-14 14:44:49 +0300
commitd987dd137bac8dca9b0015763d3106f48bb8a596 (patch)
treeef887505b3c904c548d58ec9bb6f4970a0877042 /include/linux/seqlock.h
parentc85251f8562095cd6fd63ae786354283c5318303 (diff)
parent211c17aaee644bb808fbdeef547ac99db92c01ed (diff)
Merge remote branch 'wireless-next/master' into ath6kl-next
Conflicts: drivers/net/wireless/ath/ath6kl/cfg80211.c
Diffstat (limited to 'include/linux/seqlock.h')
-rw-r--r--include/linux/seqlock.h23
1 files changed, 22 insertions, 1 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index c6db9fb33c44..600060e25ec6 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -141,7 +141,7 @@ static inline unsigned __read_seqcount_begin(const seqcount_t *s)
unsigned ret;
repeat:
- ret = s->sequence;
+ ret = ACCESS_ONCE(s->sequence);
if (unlikely(ret & 1)) {
cpu_relax();
goto repeat;
@@ -166,6 +166,27 @@ static inline unsigned read_seqcount_begin(const seqcount_t *s)
}
/**
+ * raw_seqcount_begin - begin a seq-read critical section
+ * @s: pointer to seqcount_t
+ * Returns: count to be passed to read_seqcount_retry
+ *
+ * raw_seqcount_begin opens a read critical section of the given seqcount.
+ * Validity of the critical section is tested by checking read_seqcount_retry
+ * function.
+ *
+ * Unlike read_seqcount_begin(), this function will not wait for the count
+ * to stabilize. If a writer is active when we begin, we will fail the
+ * read_seqcount_retry() instead of stabilizing at the beginning of the
+ * critical section.
+ */
+static inline unsigned raw_seqcount_begin(const seqcount_t *s)
+{
+ unsigned ret = ACCESS_ONCE(s->sequence);
+ smp_rmb();
+ return ret & ~1;
+}
+
+/**
* __read_seqcount_retry - end a seq-read critical section (without barrier)
* @s: pointer to seqcount_t
* @start: count, from read_seqcount_begin