diff options
| -rw-r--r-- | include/linux/rcutiny.h | 5 | ||||
| -rw-r--r-- | include/linux/rcutree.h | 1 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 109 |
3 files changed, 107 insertions, 8 deletions
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index d9ac7b136aea..522123050ff8 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -111,6 +111,11 @@ static inline void __kvfree_call_rcu(struct rcu_head *head, void *ptr) kvfree(ptr); } +static inline void kvfree_rcu_barrier(void) +{ + rcu_barrier(); +} + #ifdef CONFIG_KASAN_GENERIC void kvfree_call_rcu(struct rcu_head *head, void *ptr); #else diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 254244202ea9..58e7db80f3a8 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -35,6 +35,7 @@ static inline void rcu_virt_note_context_switch(void) void synchronize_rcu_expedited(void); void kvfree_call_rcu(struct rcu_head *head, void *ptr); +void kvfree_rcu_barrier(void); void rcu_barrier(void); void rcu_momentary_dyntick_idle(void); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e641cc681901..be00aac5f4e7 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3584,18 +3584,15 @@ kvfree_rcu_drain_ready(struct kfree_rcu_cpu *krcp) } /* - * This function is invoked after the KFREE_DRAIN_JIFFIES timeout. + * Return: %true if a work is queued, %false otherwise. */ -static void kfree_rcu_monitor(struct work_struct *work) +static bool +kvfree_rcu_queue_batch(struct kfree_rcu_cpu *krcp) { - struct kfree_rcu_cpu *krcp = container_of(work, - struct kfree_rcu_cpu, monitor_work.work); unsigned long flags; + bool queued = false; int i, j; - // Drain ready for reclaim. - kvfree_rcu_drain_ready(krcp); - raw_spin_lock_irqsave(&krcp->lock, flags); // Attempt to start a new batch. @@ -3634,11 +3631,27 @@ static void kfree_rcu_monitor(struct work_struct *work) // be that the work is in the pending state when // channels have been detached following by each // other. - queue_rcu_work(system_wq, &krwp->rcu_work); + queued = queue_rcu_work(system_wq, &krwp->rcu_work); } } raw_spin_unlock_irqrestore(&krcp->lock, flags); + return queued; +} + +/* + * This function is invoked after the KFREE_DRAIN_JIFFIES timeout. + */ +static void kfree_rcu_monitor(struct work_struct *work) +{ + struct kfree_rcu_cpu *krcp = container_of(work, + struct kfree_rcu_cpu, monitor_work.work); + + // Drain ready for reclaim. + kvfree_rcu_drain_ready(krcp); + + // Queue a batch for a rest. + kvfree_rcu_queue_batch(krcp); // If there is nothing to detach, it means that our job is // successfully done here. In case of having at least one @@ -3859,6 +3872,86 @@ unlock_return: } EXPORT_SYMBOL_GPL(kvfree_call_rcu); +/** + * kvfree_rcu_barrier - Wait until all in-flight kvfree_rcu() complete. + * + * Note that a single argument of kvfree_rcu() call has a slow path that + * triggers synchronize_rcu() following by freeing a pointer. It is done + * before the return from the function. Therefore for any single-argument + * call that will result in a kfree() to a cache that is to be destroyed + * during module exit, it is developer's responsibility to ensure that all + * such calls have returned before the call to kmem_cache_destroy(). + */ +void kvfree_rcu_barrier(void) +{ + struct kfree_rcu_cpu_work *krwp; + struct kfree_rcu_cpu *krcp; + bool queued; + int i, cpu; + + /* + * Firstly we detach objects and queue them over an RCU-batch + * for all CPUs. Finally queued works are flushed for each CPU. + * + * Please note. If there are outstanding batches for a particular + * CPU, those have to be finished first following by queuing a new. + */ + for_each_possible_cpu(cpu) { + krcp = per_cpu_ptr(&krc, cpu); + + /* + * Check if this CPU has any objects which have been queued for a + * new GP completion. If not(means nothing to detach), we are done + * with it. If any batch is pending/running for this "krcp", below + * per-cpu flush_rcu_work() waits its completion(see last step). + */ + if (!need_offload_krc(krcp)) + continue; + + while (1) { + /* + * If we are not able to queue a new RCU work it means: + * - batches for this CPU are still in flight which should + * be flushed first and then repeat; + * - no objects to detach, because of concurrency. + */ + queued = kvfree_rcu_queue_batch(krcp); + + /* + * Bail out, if there is no need to offload this "krcp" + * anymore. As noted earlier it can run concurrently. + */ + if (queued || !need_offload_krc(krcp)) + break; + + /* There are ongoing batches. */ + for (i = 0; i < KFREE_N_BATCHES; i++) { + krwp = &(krcp->krw_arr[i]); + flush_rcu_work(&krwp->rcu_work); + } + } + } + + /* + * Now we guarantee that all objects are flushed. + */ + for_each_possible_cpu(cpu) { + krcp = per_cpu_ptr(&krc, cpu); + + /* + * A monitor work can drain ready to reclaim objects + * directly. Wait its completion if running or pending. + */ + cancel_delayed_work_sync(&krcp->monitor_work); + + for (i = 0; i < KFREE_N_BATCHES; i++) { + krwp = &(krcp->krw_arr[i]); + flush_rcu_work(&krwp->rcu_work); + } + } +} +EXPORT_SYMBOL_GPL(kvfree_rcu_barrier); + static unsigned long kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { |