diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2012-02-27 17:55:11 +0100 |
---|---|---|
committer | Steven Rostedt <rostedt@rostedt.homelinux.com> | 2012-10-26 14:42:41 -0400 |
commit | cf7aeb6acd72889356496b3f06b346e12a3c0741 (patch) | |
tree | af49e901e40be296ca9c40fe91a2d47d57854908 | |
parent | 7118c8527f2530785a7f19ee1c40372f02c271e2 (diff) |
seqlock: Provide seq_spin_* functions
In some cases it's desirable to lock the seqlock w/o changing the
seqcount. Provide functions for this, so we can avoid open coded
constructs.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r-- | include/linux/seqlock.h | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index cc7b65d41f81..9bb7fb735144 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -188,6 +188,19 @@ static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start) } /* + * Ditto w/o barriers + */ +static inline unsigned __read_seqbegin(const seqlock_t *sl) +{ + return __read_seqcount_begin(&sl->seqcount); +} + +static inline unsigned __read_seqretry(const seqlock_t *sl, unsigned start) +{ + return __read_seqcount_retry(&sl->seqcount, start); +} + +/* * Lock out other writers and update the count. * Acts like a normal spin_lock/unlock. * Don't need preempt_disable() because that is in the spin_lock already. @@ -247,4 +260,55 @@ write_sequnlock_irqrestore(seqlock_t *sl, unsigned long flags) spin_unlock_irqrestore(&sl->lock, flags); } +/* + * Instead of open coding a spinlock and a seqcount, the following + * functions allow to serialize on the seqlock w/o touching seqcount. + */ +static inline void seq_spin_lock(seqlock_t *sl) +{ + spin_lock(&sl->lock); +} + +static inline int seq_spin_trylock(seqlock_t *sl) +{ + return spin_trylock(&sl->lock); +} + +static inline void seq_spin_unlock(seqlock_t *sl) +{ + spin_unlock(&sl->lock); +} + +static inline void assert_seq_spin_locked(seqlock_t *sl) +{ + assert_spin_locked(&sl->lock); +} + +static inline void seq_spin_lock_nested(seqlock_t *sl, int subclass) +{ + spin_lock_nested(&sl->lock, subclass); +} + +/* + * For writers which need to take/release the lock w/o updating seqcount for + * whatever reasons the following functions allow to update the count + * after the lock has been acquired or before it is released. + */ +static inline void write_seqlock_begin(seqlock_t *sl) +{ + assert_spin_locked(&sl->lock); + write_seqcount_begin(&sl->seqcount); +} + +static inline void write_seqlock_end(seqlock_t *sl) +{ + assert_spin_locked(&sl->lock); + write_seqcount_end(&sl->seqcount); +} + +static inline void write_seqlock_barrier(seqlock_t *sl) +{ + write_seqcount_barrier(&sl->seqcount); +} + #endif /* __LINUX_SEQLOCK_H */ |