Messages in this thread Patch in this message | | | Date | Thu, 15 Mar 2012 11:44:23 -0000 | From | Thomas Gleixner <> | Subject | [patch 3/5] 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> --- include/linux/seqlock.h | 66 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+)
Index: tip/include/linux/seqlock.h =================================================================== --- tip.orig/include/linux/seqlock.h +++ tip/include/linux/seqlock.h @@ -176,6 +176,21 @@ typedef struct { /* * Read side functions for starting and finalizing a read side section. + * 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); +} + +/* + * Read side functions for starting and finalizing a read side section. + * with barriers */ static inline unsigned read_seqbegin(const seqlock_t *sl) { @@ -247,4 +262,55 @@ write_sequnlock_irqrestore(seqlock_t *sl 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) +{ + lockdep_assert_held(&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) +{ + lockdep_assert_held(&sl->lock); + write_seqcount_begin(&sl->seqcount); +} + +static inline void write_seqlock_end(seqlock_t *sl) +{ + lockdep_assert_held(&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 */
| |