[RFC PATCH 4/6] seqlock: Add raw_seqbegin() for non-waiting readers

[Frederic Weisbecker]

Add the seqlock version of raw_seqcount_begin() for readers
that can't wait for writers to complete their update and
who can live with seqlock read acquirement failure.

Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
---
 include/linux/seqlock.h |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 1829905..aa845de 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -203,6 +203,11 @@ static inline unsigned read_seqbegin(const seqlock_t *sl)
 	return read_seqcount_begin(&sl->seqcount);
 }
 
+static inline unsigned raw_seqbegin(const seqlock_t *sl)
+{
+	return raw_seqcount_begin(&sl->seqcount);
+}
+
 static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start)
 {
 	return read_seqcount_retry(&sl->seqcount, start);
-- 
1.7.5.4

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