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Subject[PATCH tip/locking/core 3/3] locking/pvqspinlock: Direct lock stealing count tracking in pv_queued_spin_steal_lock
Date
This patch moves the lock stealing count tracking code into
pv_queued_spin_steal_lock instead of via a jacket function simplifying
the code.

Signed-off-by: Waiman Long <Waiman.Long@hpe.com>
---
kernel/locking/qspinlock_paravirt.h | 16 +++++++++-------
kernel/locking/qspinlock_stat.h | 13 -------------
2 files changed, 9 insertions(+), 20 deletions(-)

diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index 72cec9e..21ede57 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -55,6 +55,11 @@ struct pv_node {
};

/*
+ * Include queued spinlock statistics code
+ */
+#include "qspinlock_stat.h"
+
+/*
* By replacing the regular queued_spin_trylock() with the function below,
* it will be called once when a lock waiter enter the PV slowpath before
* being queued. By allowing one lock stealing attempt here when the pending
@@ -65,9 +70,11 @@ struct pv_node {
static inline bool pv_queued_spin_steal_lock(struct qspinlock *lock)
{
struct __qspinlock *l = (void *)lock;
+ int ret = !(atomic_read(&lock->val) & _Q_LOCKED_PENDING_MASK) &&
+ (cmpxchg(&l->locked, 0, _Q_LOCKED_VAL) == 0);

- return !(atomic_read(&lock->val) & _Q_LOCKED_PENDING_MASK) &&
- (cmpxchg(&l->locked, 0, _Q_LOCKED_VAL) == 0);
+ qstat_inc(qstat_pv_lock_stealing, ret);
+ return ret;
}

/*
@@ -138,11 +145,6 @@ static __always_inline int trylock_clear_pending(struct qspinlock *lock)
#endif /* _Q_PENDING_BITS == 8 */

/*
- * Include queued spinlock statistics code
- */
-#include "qspinlock_stat.h"
-
-/*
* Lock and MCS node addresses hash table for fast lookup
*
* Hashing is done on a per-cacheline basis to minimize the need to access
diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h
index 283a615..eb2a2c9 100644
--- a/kernel/locking/qspinlock_stat.h
+++ b/kernel/locking/qspinlock_stat.h
@@ -282,19 +282,6 @@ static inline void __pv_wait(u8 *ptr, u8 val)
#define pv_kick(c) __pv_kick(c)
#define pv_wait(p, v) __pv_wait(p, v)

-/*
- * PV unfair trylock count tracking function
- */
-static inline int qstat_spin_steal_lock(struct qspinlock *lock)
-{
- int ret = pv_queued_spin_steal_lock(lock);
-
- qstat_inc(qstat_pv_lock_stealing, ret);
- return ret;
-}
-#undef queued_spin_trylock
-#define queued_spin_trylock(l) qstat_spin_steal_lock(l)
-
#else /* CONFIG_QUEUED_LOCK_STAT */

static inline void qstat_inc(enum qlock_stats stat, bool cond) { }
--
1.7.1


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