From 334e94de9bea353156abd6f2242d3cc4a24562b0 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 18 Mar 2006 15:05:53 -0500 Subject: [PATCH] [PATCH] deal with rmmod/put_io_context() races Signed-off-by: Al Viro --- block/as-iosched.c | 15 ++++++++++++++- block/cfq-iosched.c | 16 ++++++++++++++++ block/ll_rw_blk.c | 2 ++ 3 files changed, 32 insertions(+), 1 deletion(-) diff --git a/block/as-iosched.c b/block/as-iosched.c index d2ee2af..55a997f 100644 --- a/block/as-iosched.c +++ b/block/as-iosched.c @@ -182,6 +182,9 @@ struct as_rq { static kmem_cache_t *arq_pool; +static atomic_t ioc_count = ATOMIC_INIT(0); +static struct completion *ioc_gone; + static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq); static void as_antic_stop(struct as_data *ad); @@ -193,11 +196,14 @@ static void as_antic_stop(struct as_data *ad); static void free_as_io_context(struct as_io_context *aic) { kfree(aic); + if (atomic_dec_and_test(&ioc_count) && ioc_gone) + complete(ioc_gone); } static void as_trim(struct io_context *ioc) { - kfree(ioc->aic); + if (ioc->aic) + free_as_io_context(ioc->aic); ioc->aic = NULL; } @@ -226,6 +232,7 @@ static struct as_io_context *alloc_as_io_context(void) ret->seek_total = 0; ret->seek_samples = 0; ret->seek_mean = 0; + atomic_inc(&ioc_count); } return ret; @@ -1900,7 +1907,13 @@ static int __init as_init(void) static void __exit as_exit(void) { + DECLARE_COMPLETION(all_gone); elv_unregister(&iosched_as); + ioc_gone = &all_gone; + barrier(); + if (atomic_read(&ioc_count)) + complete(ioc_gone); + synchronize_rcu(); kmem_cache_destroy(arq_pool); } diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 7102baf..3cd985b 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -91,6 +91,9 @@ static kmem_cache_t *crq_pool; static kmem_cache_t *cfq_pool; static kmem_cache_t *cfq_ioc_pool; +static atomic_t ioc_count = ATOMIC_INIT(0); +static struct completion *ioc_gone; + #define CFQ_PRIO_LISTS IOPRIO_BE_NR #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) #define cfq_class_be(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_BE) @@ -1202,13 +1205,17 @@ static void cfq_free_io_context(struct cfq_io_context *cic) { struct cfq_io_context *__cic; struct list_head *entry, *next; + int freed = 1; list_for_each_safe(entry, next, &cic->list) { __cic = list_entry(entry, struct cfq_io_context, list); kmem_cache_free(cfq_ioc_pool, __cic); + freed++; } kmem_cache_free(cfq_ioc_pool, cic); + if (atomic_sub_and_test(freed, &ioc_count) && ioc_gone) + complete(ioc_gone); } static void cfq_trim(struct io_context *ioc) @@ -1297,6 +1304,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask) cic->dtor = cfq_free_io_context; cic->exit = cfq_exit_io_context; INIT_LIST_HEAD(&cic->queue_list); + atomic_inc(&ioc_count); } return cic; @@ -1501,6 +1509,7 @@ restart: list); read_unlock(&cfq_exit_lock); kmem_cache_free(cfq_ioc_pool, cic); + atomic_dec(&ioc_count); goto restart; } @@ -1523,6 +1532,7 @@ restart: list_del(&__cic->list); read_unlock(&cfq_exit_lock); kmem_cache_free(cfq_ioc_pool, __cic); + atomic_dec(&ioc_count); goto restart; } } @@ -2510,7 +2520,13 @@ static int __init cfq_init(void) static void __exit cfq_exit(void) { + DECLARE_COMPLETION(all_gone); elv_unregister(&iosched_cfq); + ioc_gone = &all_gone; + barrier(); + if (atomic_read(&ioc_count)) + complete(ioc_gone); + synchronize_rcu(); cfq_slab_kill(); } diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index caa8fcf..6dc7691 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -3477,10 +3477,12 @@ void put_io_context(struct io_context *ioc) BUG_ON(atomic_read(&ioc->refcount) == 0); if (atomic_dec_and_test(&ioc->refcount)) { + rcu_read_lock(); if (ioc->aic && ioc->aic->dtor) ioc->aic->dtor(ioc->aic); if (ioc->cic && ioc->cic->dtor) ioc->cic->dtor(ioc->cic); + rcu_read_unlock(); kmem_cache_free(iocontext_cachep, ioc); } -- 1.8.2.3