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Commit 0ea5a520 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by John Stultz
Browse files

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: default avatarThomas 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: default avatarJohn Stultz <john.stultz@linaro.org>
parent 0e5ac3a8

include/linux/seqlock.h

+16 −0
Original line number Diff line number Diff line
@@ -116,6 +116,22 @@ static inline unsigned __read_seqcount_begin(const seqcount_t *s) 
	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