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lockmgr: tidy up slock/sunlock similar to other locks

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This commit is contained in:
Mateusz Guzik 2018-07-13 22:40:14 +00:00
parent f9ac902319
commit 95ab076d6e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=336267
1 changed files with 22 additions and 29 deletions
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51
sys/kern/kern_lock.c
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@ -112,11 +112,21 @@ CTASSERT(LK_UNLOCKED == (LK_UNLOCKED &
} \
} while (0)
#define LK_CAN_SHARE(x, flags) \
(((x) & LK_SHARE) && \
(((x) & (LK_EXCLUSIVE_WAITERS | LK_EXCLUSIVE_SPINNERS)) == 0 || \
(curthread->td_lk_slocks != 0 && !(flags & LK_NODDLKTREAT)) || \
(curthread->td_pflags & TDP_DEADLKTREAT)))
static bool __always_inline
LK_CAN_SHARE(uintptr_t x, int flags, bool fp)
{
if ((x & (LK_SHARE | LK_EXCLUSIVE_WAITERS | LK_EXCLUSIVE_SPINNERS)) ==
LK_SHARE)
return (true);
if (fp || (!(x & LK_SHARE)))
return (false);
if ((curthread->td_lk_slocks != 0 && !(flags & LK_NODDLKTREAT)) ||
(curthread->td_pflags & TDP_DEADLKTREAT))
return (true);
return (false);
}
#define LK_TRYOP(x) \
((x) & LK_NOWAIT)
@ -169,7 +179,7 @@ struct lockmgr_wait {
};
static bool __always_inline lockmgr_slock_try(struct lock *lk, uintptr_t *xp,
int flags);
int flags, bool fp);
static bool __always_inline lockmgr_sunlock_try(struct lock *lk, uintptr_t *xp);
static void
@ -498,7 +508,7 @@ lockdestroy(struct lock *lk)
}
static bool __always_inline
lockmgr_slock_try(struct lock *lk, uintptr_t *xp, int flags)
lockmgr_slock_try(struct lock *lk, uintptr_t *xp, int flags, bool fp)
{
/*
@ -509,7 +519,7 @@ lockmgr_slock_try(struct lock *lk, uintptr_t *xp, int flags)
* loop back and retry.
*/
*xp = lk->lk_lock;
while (LK_CAN_SHARE(*xp, flags)) {
while (LK_CAN_SHARE(*xp, flags, fp)) {
if (atomic_fcmpset_acq_ptr(&lk->lk_lock, xp,
*xp + LK_ONE_SHARER)) {
return (true);
@ -523,29 +533,12 @@ lockmgr_sunlock_try(struct lock *lk, uintptr_t *xp)
{
for (;;) {
/*
* If there is more than one shared lock held, just drop one
* and return.
*/
if (LK_SHARERS(*xp) > 1) {
if (LK_SHARERS(*xp) > 1 || !(*xp & LK_ALL_WAITERS)) {
if (atomic_fcmpset_rel_ptr(&lk->lk_lock, xp,
*xp - LK_ONE_SHARER))
return (true);
continue;
}
/*
* If there are not waiters on the exclusive queue, drop the
* lock quickly.
*/
if ((*xp & LK_ALL_WAITERS) == 0) {
MPASS((*xp & ~LK_EXCLUSIVE_SPINNERS) ==
LK_SHARERS_LOCK(1));
if (atomic_fcmpset_rel_ptr(&lk->lk_lock, xp,
LK_UNLOCKED))
return (true);
continue;
}
break;
}
return (false);
@ -574,7 +567,7 @@ lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
file, line, flags & LK_INTERLOCK ? ilk : NULL);
for (;;) {
if (lockmgr_slock_try(lk, &x, flags))
if (lockmgr_slock_try(lk, &x, flags, false))
break;
#ifdef HWPMC_HOOKS
PMC_SOFT_CALL( , , lock, failed);
@ -617,7 +610,7 @@ lockmgr_slock_hard(struct lock *lk, u_int flags, struct lock_object *ilk,
* if the lock can be acquired in shared mode, try
* again.
*/
if (LK_CAN_SHARE(x, flags)) {
if (LK_CAN_SHARE(x, flags, false)) {
sleepq_release(&lk->lock_object);
continue;
}
@ -932,7 +925,7 @@ lockmgr_lock_fast_path(struct lock *lk, u_int flags, struct lock_object *ilk,
file, line, flags & LK_INTERLOCK ? ilk : NULL);
if (__predict_false(lk->lock_object.lo_flags & LK_NOSHARE))
break;
if (lockmgr_slock_try(lk, &x, flags)) {
if (lockmgr_slock_try(lk, &x, flags, true)) {
lockmgr_note_shared_acquire(lk, 0, 0,
file, line, flags);
locked = true;