Update the various internal qspinlock functions to pass in the lock
value to be used as a function argument instead of hardcoding it to
_Q_LOCKED_VAL. There is no functional change.
Signed-off-by: Waiman Long <long...@redhat.com>
---
kernel/locking/qspinlock.c | 19 ++++++++++---------
kernel/locking/qspinlock_paravirt.h | 24 +++++++++++++-----------
2 files changed, 23 insertions(+), 20 deletions(-)
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index b256e2d03817..527601eab7bf 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -158,9 +158,9 @@ static __always_inline void clear_pending(struct qspinlock
*lock)
*
* Lock stealing is not allowed if this function is used.
*/
-static __always_inline void clear_pending_set_locked(struct qspinlock *lock)
+static __always_inline void clear_pending_set_locked(struct qspinlock *lock,
const u8 lockval)
{
- WRITE_ONCE(lock->locked_pending, _Q_LOCKED_VAL);
+ WRITE_ONCE(lock->locked_pending, lockval);
}
/*
@@ -202,9 +202,9 @@ static __always_inline void clear_pending(struct qspinlock
*lock)
*
* *,1,0 -> *,0,1
*/
-static __always_inline void clear_pending_set_locked(struct qspinlock *lock)
+static __always_inline void clear_pending_set_locked(struct qspinlock *lock,
const u8 lockval)
{
- atomic_add(-_Q_PENDING_VAL + _Q_LOCKED_VAL, &lock->val);
+ atomic_add(-_Q_PENDING_VAL + lockval, &lock->val);
}
/**
@@ -258,9 +258,9 @@ static __always_inline u32
queued_fetch_set_pending_acquire(struct qspinlock *lo
*
* *,*,0 -> *,0,1
*/
-static __always_inline void set_locked(struct qspinlock *lock)
+static __always_inline void set_locked(struct qspinlock *lock, const u8
lockval)
{
- WRITE_ONCE(lock->locked, _Q_LOCKED_VAL);
+ WRITE_ONCE(lock->locked, lockval);
}
@@ -317,6 +317,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32
val)
struct mcs_spinlock *prev, *next, *node;
u32 old, tail;
int idx;
+ const u8 lockval = _Q_LOCKED_VAL;
BUILD_BUG_ON(CONFIG_NR_CPUS >= (1U << _Q_TAIL_CPU_BITS));
@@ -386,7 +387,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32
val)
*
* 0,1,0 -> 0,0,1
*/
- clear_pending_set_locked(lock);
+ clear_pending_set_locked(lock, lockval);
lockevent_inc(lock_pending);
return;
@@ -529,7 +530,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32
val)
* PENDING will make the uncontended transition fail.
*/
if ((val & _Q_TAIL_MASK) == tail) {
- if (atomic_try_cmpxchg_relaxed(&lock->val, &val, _Q_LOCKED_VAL))
+ if (atomic_try_cmpxchg_relaxed(&lock->val, &val, lockval))
goto release; /* No contention */
}
@@ -538,7 +539,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32
val)
* which will then detect the remaining tail and queue behind us
* ensuring we'll see a @next.
*/
- set_locked(lock);
+ set_locked(lock, lockval);
/*
* contended path; wait for next if not observed yet, release.
diff --git a/kernel/locking/qspinlock_paravirt.h
b/kernel/locking/qspinlock_paravirt.h
index 17878e531f51..c8558876fc69 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -80,6 +80,8 @@ struct pv_node {
#define queued_spin_trylock(l) pv_hybrid_queued_unfair_trylock(l)
static inline bool pv_hybrid_queued_unfair_trylock(struct qspinlock *lock)
{
+ const u8 lockval = _Q_LOCKED_VAL;
+
/*
* Stay in unfair lock mode as long as queued mode waiters are
* present in the MCS wait queue but the pending bit isn't set.
@@ -88,7 +90,7 @@ static inline bool pv_hybrid_queued_unfair_trylock(struct
qspinlock *lock)
int val = atomic_read(&lock->val);
if (!(val & _Q_LOCKED_PENDING_MASK) &&
- (cmpxchg_acquire(&lock->locked, 0, _Q_LOCKED_VAL) == 0)) {
+ (cmpxchg_acquire(&lock->locked, 0, lockval) == 0)) {
lockevent_inc(pv_lock_stealing);
return true;
}
@@ -112,15 +114,15 @@ static __always_inline void set_pending(struct qspinlock
*lock)
}
/*
- * The pending bit check in pv_queued_spin_steal_lock() isn't a memory
+ * The pending bit check in pv_hybrid_queued_unfair_trylock() isn't a memory
* barrier. Therefore, an atomic cmpxchg_acquire() is used to acquire the
* lock just to be sure that it will get it.
*/
-static __always_inline int trylock_clear_pending(struct qspinlock *lock)
+static __always_inline int trylock_clear_pending(struct qspinlock *lock, const
u8 lockval)
{
return !READ_ONCE(lock->locked) &&
(cmpxchg_acquire(&lock->locked_pending, _Q_PENDING_VAL,
- _Q_LOCKED_VAL) == _Q_PENDING_VAL);
+ lockval) == _Q_PENDING_VAL);
}
#else /* _Q_PENDING_BITS == 8 */
static __always_inline void set_pending(struct qspinlock *lock)
@@ -128,7 +130,7 @@ static __always_inline void set_pending(struct qspinlock
*lock)
atomic_or(_Q_PENDING_VAL, &lock->val);
}
-static __always_inline int trylock_clear_pending(struct qspinlock *lock)
+static __always_inline int trylock_clear_pending(struct qspinlock *lock, const
u8 lockval)
{
int val = atomic_read(&lock->val);
@@ -142,7 +144,7 @@ static __always_inline int trylock_clear_pending(struct
qspinlock *lock)
* Try to clear pending bit & set locked bit
*/
old = val;
- new = (val & ~_Q_PENDING_MASK) | _Q_LOCKED_VAL;
+ new = (val & ~_Q_PENDING_MASK) | lockval;
val = atomic_cmpxchg_acquire(&lock->val, old, new);
if (val == old)
@@ -406,6 +408,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct
mcs_spinlock *node)
struct qspinlock **lp = NULL;
int waitcnt = 0;
int loop;
+ const u8 lockval = _Q_LOCKED_VAL;
/*
* If pv_kick_node() already advanced our state, we don't need to
@@ -432,7 +435,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct
mcs_spinlock *node)
*/
set_pending(lock);
for (loop = SPIN_THRESHOLD; loop; loop--) {
- if (trylock_clear_pending(lock))
+ if (trylock_clear_pending(lock, lockval))
goto gotlock;
cpu_relax();
}
@@ -459,7 +462,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct
mcs_spinlock *node)
* Change the lock value back to _Q_LOCKED_VAL
* and unhash the table.
*/
- WRITE_ONCE(lock->locked, _Q_LOCKED_VAL);
+ WRITE_ONCE(lock->locked, lockval);
WRITE_ONCE(*lp, NULL);
goto gotlock;
}
@@ -544,14 +547,13 @@ __pv_queued_spin_unlock_slowpath(struct qspinlock *lock,
u8 locked)
#ifndef __pv_queued_spin_unlock
__visible void __pv_queued_spin_unlock(struct qspinlock *lock)
{
- u8 locked;
-
/*
* We must not unlock if SLOW, because in that case we must first
* unhash. Otherwise it would be possible to have multiple @lock
* entries, which would be BAD.
*/
- locked = cmpxchg_release(&lock->locked, _Q_LOCKED_VAL, 0);
+ u8 locked = cmpxchg_release(&lock->locked, _Q_LOCKED_VAL, 0);
+
if (likely(locked == _Q_LOCKED_VAL))
return;
--
2.18.1
