diff options
| -rw-r--r-- | include/asm-generic/rqspinlock.h | 2 | ||||
| -rw-r--r-- | kernel/bpf/rqspinlock.c | 32 | ||||
| -rw-r--r-- | kernel/locking/lock_events_list.h | 5 |
3 files changed, 33 insertions, 6 deletions
diff --git a/include/asm-generic/rqspinlock.h b/include/asm-generic/rqspinlock.h index 5dd4dd8aee69..9bd11cb7acd6 100644 --- a/include/asm-generic/rqspinlock.h +++ b/include/asm-generic/rqspinlock.h @@ -15,7 +15,7 @@ struct qspinlock; typedef struct qspinlock rqspinlock_t; -extern void resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val); +extern int resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val); /* * Default timeout for waiting loops is 0.25 seconds diff --git a/kernel/bpf/rqspinlock.c b/kernel/bpf/rqspinlock.c index d429b923b58f..262294cfd36f 100644 --- a/kernel/bpf/rqspinlock.c +++ b/kernel/bpf/rqspinlock.c @@ -138,6 +138,10 @@ static DEFINE_PER_CPU_ALIGNED(struct qnode, rqnodes[_Q_MAX_NODES]); * @lock: Pointer to queued spinlock structure * @val: Current value of the queued spinlock 32-bit word * + * Return: + * * 0 - Lock was acquired successfully. + * * -ETIMEDOUT - Lock acquisition failed because of timeout. + * * (queue tail, pending bit, lock value) * * fast : slow : unlock @@ -154,12 +158,12 @@ static DEFINE_PER_CPU_ALIGNED(struct qnode, rqnodes[_Q_MAX_NODES]); * contended : (*,x,y) +--> (*,0,0) ---> (*,0,1) -' : * queue : ^--' : */ -void __lockfunc resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val) +int __lockfunc resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val) { struct mcs_spinlock *prev, *next, *node; struct rqspinlock_timeout ts; + int idx, ret = 0; u32 old, tail; - int idx; BUILD_BUG_ON(CONFIG_NR_CPUS >= (1U << _Q_TAIL_CPU_BITS)); @@ -217,8 +221,25 @@ void __lockfunc resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val) * clear_pending_set_locked() implementations imply full * barriers. */ - if (val & _Q_LOCKED_MASK) - smp_cond_load_acquire(&lock->locked, !VAL); + if (val & _Q_LOCKED_MASK) { + RES_RESET_TIMEOUT(ts, RES_DEF_TIMEOUT); + res_smp_cond_load_acquire(&lock->locked, !VAL || RES_CHECK_TIMEOUT(ts, ret)); + } + + if (ret) { + /* + * We waited for the locked bit to go back to 0, as the pending + * waiter, but timed out. We need to clear the pending bit since + * we own it. Once a stuck owner has been recovered, the lock + * must be restored to a valid state, hence removing the pending + * bit is necessary. + * + * *,1,* -> *,0,* + */ + clear_pending(lock); + lockevent_inc(rqspinlock_lock_timeout); + return ret; + } /* * take ownership and clear the pending bit. @@ -227,7 +248,7 @@ void __lockfunc resilient_queued_spin_lock_slowpath(rqspinlock_t *lock, u32 val) */ clear_pending_set_locked(lock); lockevent_inc(lock_pending); - return; + return 0; /* * End of pending bit optimistic spinning and beginning of MCS @@ -378,5 +399,6 @@ release: * release the node */ __this_cpu_dec(rqnodes[0].mcs.count); + return 0; } EXPORT_SYMBOL_GPL(resilient_queued_spin_lock_slowpath); diff --git a/kernel/locking/lock_events_list.h b/kernel/locking/lock_events_list.h index 97fb6f3f840a..c5286249994d 100644 --- a/kernel/locking/lock_events_list.h +++ b/kernel/locking/lock_events_list.h @@ -50,6 +50,11 @@ LOCK_EVENT(lock_no_node) /* # of locking ops w/o using percpu node */ #endif /* CONFIG_QUEUED_SPINLOCKS */ /* + * Locking events for Resilient Queued Spin Lock + */ +LOCK_EVENT(rqspinlock_lock_timeout) /* # of locking ops that timeout */ + +/* * Locking events for rwsem */ LOCK_EVENT(rwsem_sleep_reader) /* # of reader sleeps */ |