diff options
| -rw-r--r-- | block/cfq-iosched.c | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 4df3f0522435..d01b411c72f0 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1142,6 +1142,9 @@ static void cfq_put_queue(struct cfq_queue *cfqq) kmem_cache_free(cfq_pool, cfqq); } +/* + * Must always be called with the rcu_read_lock() held + */ static void __call_for_each_cic(struct io_context *ioc, void (*func)(struct io_context *, struct cfq_io_context *)) @@ -1197,6 +1200,11 @@ static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic) cfq_cic_free(cic); } +/* + * Must be called with rcu_read_lock() held or preemption otherwise disabled. + * Only two callers of this - ->dtor() which is called with the rcu_read_lock(), + * and ->trim() which is called with the task lock held + */ static void cfq_free_io_context(struct io_context *ioc) { /* @@ -1502,20 +1510,24 @@ static struct cfq_io_context * cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) { struct cfq_io_context *cic; + unsigned long flags; void *k; if (unlikely(!ioc)) return NULL; + rcu_read_lock(); + /* * we maintain a last-hit cache, to avoid browsing over the tree */ cic = rcu_dereference(ioc->ioc_data); - if (cic && cic->key == cfqd) + if (cic && cic->key == cfqd) { + rcu_read_unlock(); return cic; + } do { - rcu_read_lock(); cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd); rcu_read_unlock(); if (!cic) @@ -1524,10 +1536,13 @@ cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc) k = cic->key; if (unlikely(!k)) { cfq_drop_dead_cic(cfqd, ioc, cic); + rcu_read_lock(); continue; } + spin_lock_irqsave(&ioc->lock, flags); rcu_assign_pointer(ioc->ioc_data, cic); + spin_unlock_irqrestore(&ioc->lock, flags); break; } while (1); @@ -2134,6 +2149,10 @@ static void *cfq_init_queue(struct request_queue *q) static void cfq_slab_kill(void) { + /* + * Caller already ensured that pending RCU callbacks are completed, + * so we should have no busy allocations at this point. + */ if (cfq_pool) kmem_cache_destroy(cfq_pool); if (cfq_ioc_pool) @@ -2292,6 +2311,11 @@ static void __exit cfq_exit(void) ioc_gone = &all_gone; /* ioc_gone's update must be visible before reading ioc_count */ smp_wmb(); + + /* + * this also protects us from entering cfq_slab_kill() with + * pending RCU callbacks + */ if (elv_ioc_count_read(ioc_count)) wait_for_completion(ioc_gone); cfq_slab_kill(); |