From 95c354fe9f7d6decc08a92aa26eb233ecc2155bf Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 30 Jan 2008 13:31:20 +0100 Subject: spinlock: lockbreak cleanup The break_lock data structure and code for spinlocks is quite nasty. Not only does it double the size of a spinlock but it changes locking to a potentially less optimal trylock. Put all of that under CONFIG_GENERIC_LOCKBREAK, and introduce a __raw_spin_is_contended that uses the lock data itself to determine whether there are waiters on the lock, to be used if CONFIG_GENERIC_LOCKBREAK is not set. Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to decouple it from the spinlock implementation, and make it typesafe (rwlocks do not have any need_lockbreak sites -- why do they even get bloated up with that break_lock then?). Signed-off-by: Nick Piggin Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- include/linux/sched.h | 21 +++++++-------------- 1 file changed, 7 insertions(+), 14 deletions(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 2d0546e884ea..9d4797609aa5 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1922,23 +1922,16 @@ extern int cond_resched_softirq(void); /* * Does a critical section need to be broken due to another - * task waiting?: + * task waiting?: (technically does not depend on CONFIG_PREEMPT, + * but a general need for low latency) */ -#if defined(CONFIG_PREEMPT) && defined(CONFIG_SMP) -# define need_lockbreak(lock) ((lock)->break_lock) -#else -# define need_lockbreak(lock) 0 -#endif - -/* - * Does a critical section need to be broken due to another - * task waiting or preemption being signalled: - */ -static inline int lock_need_resched(spinlock_t *lock) +static inline int spin_needbreak(spinlock_t *lock) { - if (need_lockbreak(lock) || need_resched()) - return 1; +#ifdef CONFIG_PREEMPT + return spin_is_contended(lock); +#else return 0; +#endif } /* -- cgit v1.2.3