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| author | Thomas Gleixner <tglx@linutronix.de> | 2014-07-16 21:05:20 +0000 |
|---|---|---|
| committer | John Stultz <john.stultz@linaro.org> | 2014-07-23 15:01:54 -0700 |
| commit | 0ea5a520f73ca31abc4c10b6d5bc14a884a0641b (patch) | |
| tree | 8d97283712062b622411281cd5bb7f19e9447689 /include/linux/seqlock.h | |
| parent | 0e5ac3a8b100469ea154f87dd57b685fbdd356f6 (diff) | |
| download | lwn-0ea5a520f73ca31abc4c10b6d5bc14a884a0641b.tar.gz lwn-0ea5a520f73ca31abc4c10b6d5bc14a884a0641b.zip | |
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@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'include/linux/seqlock.h')
| -rw-r--r-- | include/linux/seqlock.h | 16 |
1 files changed, 16 insertions, 0 deletions
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 @@ -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 |