diff options
Diffstat (limited to 'kernel/locking/qspinlock.c')
| -rw-r--r-- | kernel/locking/qspinlock.c | 31 |
1 files changed, 20 insertions, 11 deletions
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index b9515fcc9b29..7d96bed718e4 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -22,6 +22,7 @@ #include <linux/prefetch.h> #include <asm/byteorder.h> #include <asm/qspinlock.h> +#include <trace/events/lock.h> /* * Include queued spinlock statistics code @@ -219,21 +220,18 @@ static __always_inline void clear_pending_set_locked(struct qspinlock *lock) */ static __always_inline u32 xchg_tail(struct qspinlock *lock, u32 tail) { - u32 old, new, val = atomic_read(&lock->val); + u32 old, new; - for (;;) { - new = (val & _Q_LOCKED_PENDING_MASK) | tail; + old = atomic_read(&lock->val); + do { + new = (old & _Q_LOCKED_PENDING_MASK) | tail; /* * We can use relaxed semantics since the caller ensures that * the MCS node is properly initialized before updating the * tail. */ - old = atomic_cmpxchg_relaxed(&lock->val, val, new); - if (old == val) - break; + } while (!atomic_try_cmpxchg_relaxed(&lock->val, &old, new)); - val = old; - } return old; } #endif /* _Q_PENDING_BITS == 8 */ @@ -312,7 +310,7 @@ static __always_inline u32 __pv_wait_head_or_lock(struct qspinlock *lock, * contended : (*,x,y) +--> (*,0,0) ---> (*,0,1) -' : * queue : ^--' : */ -void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) +void __lockfunc queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) { struct mcs_spinlock *prev, *next, *node; u32 old, tail; @@ -370,7 +368,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) /* * We're pending, wait for the owner to go away. * - * 0,1,1 -> 0,1,0 + * 0,1,1 -> *,1,0 * * this wait loop must be a load-acquire such that we match the * store-release that clears the locked bit and create lock @@ -379,7 +377,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) * barriers. */ if (val & _Q_LOCKED_MASK) - atomic_cond_read_acquire(&lock->val, !(VAL & _Q_LOCKED_MASK)); + smp_cond_load_acquire(&lock->locked, !VAL); /* * take ownership and clear the pending bit. @@ -401,6 +399,8 @@ pv_queue: idx = node->count++; tail = encode_tail(smp_processor_id(), idx); + trace_contention_begin(lock, LCB_F_SPIN); + /* * 4 nodes are allocated based on the assumption that there will * not be nested NMIs taking spinlocks. That may not be true in @@ -554,6 +554,8 @@ locked: pv_kick_node(lock, next); release: + trace_contention_end(lock, 0); + /* * release the node */ @@ -581,4 +583,11 @@ EXPORT_SYMBOL(queued_spin_lock_slowpath); #include "qspinlock_paravirt.h" #include "qspinlock.c" +bool nopvspin; +static __init int parse_nopvspin(char *arg) +{ + nopvspin = true; + return 0; +} +early_param("nopvspin", parse_nopvspin); #endif |