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rwsem use kernel provided owner when possible 

If CONFIG_RWSEM_SPIN_ON_OWNER is defined, rw_semaphore will have an owner
field, so we don't need our own.

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #473
This commit is contained in:
Chunwei Chen 2015-09-01 23:28:02 +08:00 committed by Brian Behlendorf
parent 4f8e643afe
commit a00b3eb58f
1 changed files with 22 additions and 1 deletions
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23
include/sys/rwlock.h
View File

@ -40,29 +40,47 @@ typedef enum {
RW_READER = 2
} krw_t;
/*
* If CONFIG_RWSEM_SPIN_ON_OWNER is defined, rw_semaphore will have an owner
* field, so we don't need our own.
*/
typedef struct {
struct rw_semaphore rw_rwlock;
#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
kthread_t *rw_owner;
#endif
} krwlock_t;
#define SEM(rwp) ((struct rw_semaphore *)(rwp))
#define SEM(rwp) (&(rwp)->rw_rwlock)
static inline void
spl_rw_set_owner(krwlock_t *rwp)
{
/*
* If CONFIG_RWSEM_SPIN_ON_OWNER is defined, down_write, up_write,
* downgrade_write and __init_rwsem will set/clear owner for us.
*/
#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
rwp->rw_owner = current;
#endif
}
static inline void
spl_rw_clear_owner(krwlock_t *rwp)
{
#ifndef CONFIG_RWSEM_SPIN_ON_OWNER
rwp->rw_owner = NULL;
#endif
}
static inline kthread_t *
rw_owner(krwlock_t *rwp)
{
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
return SEM(rwp)->owner;
#else
return rwp->rw_owner;
#endif
}
static inline int
@ -153,6 +171,9 @@ RW_LOCK_HELD(krwlock_t *rwp)
})
#if defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
#error spinlock rwsem should not have spin on owner
#endif
/*
* For the generic implementations of rw-semaphores the following is
* true. If your semaphore implementation internally represents the