diff options
Diffstat (limited to 'kernel/locking/qspinlock.c')
| -rw-r--r-- | kernel/locking/qspinlock.c | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index e06f67e021d9..b51494a50b1e 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -465,24 +465,21 @@ locked: * and nobody is pending, clear the tail code and grab the lock. * Otherwise, we only need to grab the lock. */ - for (;;) { - /* In the PV case we might already have _Q_LOCKED_VAL set */ - if ((val & _Q_TAIL_MASK) != tail || (val & _Q_PENDING_MASK)) { - set_locked(lock); - break; - } + + /* In the PV case we might already have _Q_LOCKED_VAL set */ + if ((val & _Q_TAIL_MASK) == tail) { /* * The smp_cond_load_acquire() call above has provided the - * necessary acquire semantics required for locking. At most - * two iterations of this loop may be ran. + * necessary acquire semantics required for locking. */ old = atomic_cmpxchg_relaxed(&lock->val, val, _Q_LOCKED_VAL); if (old == val) - goto release; /* No contention */ - - val = old; + goto release; /* No contention */ } + /* Either somebody is queued behind us or _Q_PENDING_VAL is set */ + set_locked(lock); + /* * contended path; wait for next if not observed yet, release. */ |