[PATCH 1/2] seqlock: Use raw_ prefix instead of _no_lockdep

From: John Stultz
Date: Thu Jan 02 2014 - 18:11:45 EST


Linus disliked the _no_lockdep() naming, so instead
use the more-consistent raw_* prefix to the non-lockdep
enabled seqcount methods.

This also adds raw_ methods for the write operations
as well, which will be utilized in a following patch.

Cc: Krzysztof HaÅasa <khalasa@xxxxxxx>
Cc: Uwe Kleine-KÃnig <u.kleine-koenig@xxxxxxxxxxxxxx>
Cc: Willy Tarreau <w@xxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>,
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
arch/x86/vdso/vclock_gettime.c | 8 ++++----
include/linux/seqlock.h | 27 +++++++++++++++++++--------
2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index 2ada505..eb5d7a5 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -178,7 +178,7 @@ notrace static int __always_inline do_realtime(struct timespec *ts)

ts->tv_nsec = 0;
do {
- seq = read_seqcount_begin_no_lockdep(&gtod->seq);
+ seq = raw_read_seqcount_begin(&gtod->seq);
mode = gtod->clock.vclock_mode;
ts->tv_sec = gtod->wall_time_sec;
ns = gtod->wall_time_snsec;
@@ -198,7 +198,7 @@ notrace static int do_monotonic(struct timespec *ts)

ts->tv_nsec = 0;
do {
- seq = read_seqcount_begin_no_lockdep(&gtod->seq);
+ seq = raw_read_seqcount_begin(&gtod->seq);
mode = gtod->clock.vclock_mode;
ts->tv_sec = gtod->monotonic_time_sec;
ns = gtod->monotonic_time_snsec;
@@ -214,7 +214,7 @@ notrace static int do_realtime_coarse(struct timespec *ts)
{
unsigned long seq;
do {
- seq = read_seqcount_begin_no_lockdep(&gtod->seq);
+ seq = raw_read_seqcount_begin(&gtod->seq);
ts->tv_sec = gtod->wall_time_coarse.tv_sec;
ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;
} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
@@ -225,7 +225,7 @@ notrace static int do_monotonic_coarse(struct timespec *ts)
{
unsigned long seq;
do {
- seq = read_seqcount_begin_no_lockdep(&gtod->seq);
+ seq = raw_read_seqcount_begin(&gtod->seq);
ts->tv_sec = gtod->monotonic_time_coarse.tv_sec;
ts->tv_nsec = gtod->monotonic_time_coarse.tv_nsec;
} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index cf87a24..535f158 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -117,15 +117,15 @@ repeat:
}

/**
- * read_seqcount_begin_no_lockdep - start seq-read critical section w/o lockdep
+ * 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
*
- * read_seqcount_begin_no_lockdep opens a read critical section of the given
+ * raw_read_seqcount_begin opens a read critical section of the given
* seqcount, but without any lockdep checking. Validity of the critical
* section is tested by checking read_seqcount_retry function.
*/
-static inline unsigned read_seqcount_begin_no_lockdep(const seqcount_t *s)
+static inline unsigned raw_read_seqcount_begin(const seqcount_t *s)
{
unsigned ret = __read_seqcount_begin(s);
smp_rmb();
@@ -144,7 +144,7 @@ static inline unsigned read_seqcount_begin_no_lockdep(const seqcount_t *s)
static inline unsigned read_seqcount_begin(const seqcount_t *s)
{
seqcount_lockdep_reader_access(s);
- return read_seqcount_begin_no_lockdep(s);
+ return raw_read_seqcount_begin(s);
}

/**
@@ -206,14 +206,26 @@ static inline int read_seqcount_retry(const seqcount_t *s, unsigned start)
}


+
+static inline void raw_write_seqcount_begin(seqcount_t *s)
+{
+ s->sequence++;
+ smp_wmb();
+}
+
+static inline void raw_write_seqcount_end(seqcount_t *s)
+{
+ smp_wmb();
+ s->sequence++;
+}
+
/*
* Sequence counter only version assumes that callers are using their
* own mutexing.
*/
static inline void write_seqcount_begin_nested(seqcount_t *s, int subclass)
{
- s->sequence++;
- smp_wmb();
+ raw_write_seqcount_begin(s);
seqcount_acquire(&s->dep_map, subclass, 0, _RET_IP_);
}

@@ -225,8 +237,7 @@ static inline void write_seqcount_begin(seqcount_t *s)
static inline void write_seqcount_end(seqcount_t *s)
{
seqcount_release(&s->dep_map, 1, _RET_IP_);
- smp_wmb();
- s->sequence++;
+ raw_write_seqcount_end(s);
}

/**
--
1.8.3.2

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