Commit-ID: 0ea5a520f73ca31abc4c10b6d5bc14a884a0641b
Gitweb: http://git.kernel.org/tip/0ea5a520f73ca31abc4c10b6d5bc14a884a0641b
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Wed, 16 Jul 2014 21:05:20 +0000
Committer: John Stultz <john.stultz@xxxxxxxxxx>
CommitDate: Wed, 23 Jul 2014 15:01:54 -0700
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 <tglx@xxxxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
include/linux/seqlock.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index 535f158..dcc64b9 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -117,6 +117,22 @@ repeat:
}
/**
+ * 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
* Returns: count to be passed to read_seqcount_retry
--
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