this patch, against BK-curr, implements a nonintrusive spin-polling loop for the SMP+PREEMPT spinlock/rwlock variants, using the new *_can_lock() primitives. (The patch also adds *_can_lock() to the UP branch of spinlock.h, for completeness.)
build- and boot-tested on x86 SMP+PREEMPT and SMP+!PREEMPT. Ingo Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]> --- linux/kernel/spinlock.c.orig +++ linux/kernel/spinlock.c @@ -174,7 +174,7 @@ EXPORT_SYMBOL(_write_lock); */ #define BUILD_LOCK_OPS(op, locktype) \ -void __lockfunc _##op##_lock(locktype *lock) \ +void __lockfunc _##op##_lock(locktype##_t *lock) \ { \ preempt_disable(); \ for (;;) { \ @@ -183,14 +183,15 @@ void __lockfunc _##op##_lock(locktype *l preempt_enable(); \ if (!(lock)->break_lock) \ (lock)->break_lock = 1; \ - cpu_relax(); \ + while (!op##_can_lock(lock) && (lock)->break_lock) \ + cpu_relax(); \ preempt_disable(); \ } \ } \ \ EXPORT_SYMBOL(_##op##_lock); \ \ -unsigned long __lockfunc _##op##_lock_irqsave(locktype *lock) \ +unsigned long __lockfunc _##op##_lock_irqsave(locktype##_t *lock) \ { \ unsigned long flags; \ \ @@ -204,7 +205,8 @@ unsigned long __lockfunc _##op##_lock_ir preempt_enable(); \ if (!(lock)->break_lock) \ (lock)->break_lock = 1; \ - cpu_relax(); \ + while (!op##_can_lock(lock) && (lock)->break_lock) \ + cpu_relax(); \ preempt_disable(); \ } \ return flags; \ @@ -212,14 +214,14 @@ unsigned long __lockfunc _##op##_lock_ir \ EXPORT_SYMBOL(_##op##_lock_irqsave); \ \ -void __lockfunc _##op##_lock_irq(locktype *lock) \ +void __lockfunc _##op##_lock_irq(locktype##_t *lock) \ { \ _##op##_lock_irqsave(lock); \ } \ \ EXPORT_SYMBOL(_##op##_lock_irq); \ \ -void __lockfunc _##op##_lock_bh(locktype *lock) \ +void __lockfunc _##op##_lock_bh(locktype##_t *lock) \ { \ unsigned long flags; \ \ @@ -244,9 +246,9 @@ EXPORT_SYMBOL(_##op##_lock_bh) * _[spin|read|write]_lock_irqsave() * _[spin|read|write]_lock_bh() */ -BUILD_LOCK_OPS(spin, spinlock_t); -BUILD_LOCK_OPS(read, rwlock_t); -BUILD_LOCK_OPS(write, rwlock_t); +BUILD_LOCK_OPS(spin, spinlock); +BUILD_LOCK_OPS(read, rwlock); +BUILD_LOCK_OPS(write, rwlock); #endif /* CONFIG_PREEMPT */ --- linux/include/linux/spinlock.h.orig +++ linux/include/linux/spinlock.h @@ -221,6 +221,8 @@ typedef struct { #define _raw_read_unlock(lock) do { (void)(lock); } while(0) #define _raw_write_lock(lock) do { (void)(lock); } while(0) #define _raw_write_unlock(lock) do { (void)(lock); } while(0) +#define read_can_lock(lock) (((void)(lock), 1)) +#define write_can_lock(lock) (((void)(lock), 1)) #define _raw_read_trylock(lock) ({ (void)(lock); (1); }) #define _raw_write_trylock(lock) ({ (void)(lock); (1); }) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/