From dbecf3ab40b5a6cc4499543778cd9f9682c0abad Mon Sep 17 00:00:00 2001 From: OGAWA Hirofumi Date: Tue, 18 Apr 2006 09:45:18 +0200 Subject: [PATCH] [PATCH 2/2] cfq: fix cic's rbtree traversal When queue dies, we set cic->key=NULL as dead mark. So, when we traverse a rbtree, we must check whether it's still valid key. if it was invalidated, drop it, then restart the traversal from top. Signed-off-by: OGAWA Hirofumi Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 01820b1094e9..246feae16c60 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1472,15 +1472,31 @@ out: return cfqq; } +static void +cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic) +{ + read_lock(&cfq_exit_lock); + rb_erase(&cic->rb_node, &ioc->cic_root); + read_unlock(&cfq_exit_lock); + kmem_cache_free(cfq_ioc_pool, cic); + atomic_dec(&ioc_count); +} + static struct cfq_io_context * cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc) { - struct rb_node *n = ioc->cic_root.rb_node; + struct rb_node *n; struct cfq_io_context *cic; void *key = cfqd; +restart: + n = ioc->cic_root.rb_node; while (n) { cic = rb_entry(n, struct cfq_io_context, rb_node); + if (unlikely(!cic->key)) { + cfq_drop_dead_cic(ioc, cic); + goto restart; + } if (key < cic->key) n = n->rb_left; @@ -1497,20 +1513,24 @@ static inline void cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, struct cfq_io_context *cic) { - struct rb_node **p = &ioc->cic_root.rb_node; - struct rb_node *parent = NULL; + struct rb_node **p; + struct rb_node *parent; struct cfq_io_context *__cic; - read_lock(&cfq_exit_lock); - cic->ioc = ioc; cic->key = cfqd; ioc->set_ioprio = cfq_ioc_set_ioprio; - +restart: + parent = NULL; + p = &ioc->cic_root.rb_node; while (*p) { parent = *p; __cic = rb_entry(parent, struct cfq_io_context, rb_node); + if (unlikely(!__cic->key)) { + cfq_drop_dead_cic(ioc, cic); + goto restart; + } if (cic->key < __cic->key) p = &(*p)->rb_left; @@ -1520,6 +1540,7 @@ cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc, BUG(); } + read_lock(&cfq_exit_lock); rb_link_node(&cic->rb_node, parent, p); rb_insert_color(&cic->rb_node, &ioc->cic_root); list_add(&cic->queue_list, &cfqd->cic_list); -- 2.20.1