From 0ea5a520f73ca31abc4c10b6d5bc14a884a0641b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 16 Jul 2014 21:05:20 +0000 Subject: [PATCH] seqcount: Provide raw_read_seqcount() raw_read_seqcount opens a read critical section of the given seqcount without any lockdep checking and without checking or masking the LSB. Calling code is responsible for handling that. Preparatory patch to provide a NMI safe clock monotonic accessor function. Signed-off-by: Thomas Gleixner Cc: John Stultz Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Mathieu Desnoyers Signed-off-by: John Stultz --- include/linux/seqlock.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 535f158977b9..dcc64b9bfc41 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -116,6 +116,22 @@ repeat: return ret; } +/** + * raw_read_seqcount - Read the raw seqcount + * @s: pointer to seqcount_t + * Returns: count to be passed to read_seqcount_retry + * + * raw_read_seqcount opens a read critical section of the given + * seqcount without any lockdep checking and without checking or + * masking the LSB. Calling code is responsible for handling that. + */ +static inline unsigned raw_read_seqcount(const seqcount_t *s) +{ + unsigned ret = ACCESS_ONCE(s->sequence); + smp_rmb(); + return ret; +} + /** * raw_read_seqcount_begin - start seq-read critical section w/o lockdep * @s: pointer to seqcount_t -- 2.20.1