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| author | Jens Axboe <jens.axboe@oracle.com> | 2008-05-29 09:32:08 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-07-03 13:21:12 +0200 |
| commit | 9a11b4ed0e7c44bca7c939aa544c3c47aae40c12 (patch) | |
| tree | 438312dda8a63e0704c2ddbdea958f0d729c6c7e | |
| parent | c461a973118346d5c103aaaddd62e53939fd7c67 (diff) | |
| download | linux-9a11b4ed0e7c44bca7c939aa544c3c47aae40c12.tar.bz2 | |
cfq-iosched: properly protect ioc_gone and ioc count
If we have multiple tasks freeing cfq_io_contexts when cfq-iosched
is being unloaded, we could complete() ioc_gone twice. Fix that by
protecting ioc_gone complete() and clearing with a spinlock for
just that purpose. Doesn't matter from a performance perspective,
since it'll only enter that path when ioc_gone != NULL (when cfq-iosched
is being rmmod'ed).
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
| -rw-r--r-- | block/cfq-iosched.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index d01b411c72f0..32aa3674f8a3 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -48,6 +48,7 @@ static struct kmem_cache *cfq_ioc_pool; static DEFINE_PER_CPU(unsigned long, ioc_count); static struct completion *ioc_gone; +static DEFINE_SPINLOCK(ioc_gone_lock); #define CFQ_PRIO_LISTS IOPRIO_BE_NR #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) @@ -1177,8 +1178,19 @@ static void cfq_cic_free_rcu(struct rcu_head *head) kmem_cache_free(cfq_ioc_pool, cic); elv_ioc_count_dec(ioc_count); - if (ioc_gone && !elv_ioc_count_read(ioc_count)) - complete(ioc_gone); + if (ioc_gone) { + /* + * CFQ scheduler is exiting, grab exit lock and check + * the pending io context count. If it hits zero, + * complete ioc_gone and set it back to NULL + */ + spin_lock(&ioc_gone_lock); + if (ioc_gone && !elv_ioc_count_read(ioc_count)) { + complete(ioc_gone); + ioc_gone = NULL; + } + spin_unlock(&ioc_gone_lock); + } } static void cfq_cic_free(struct cfq_io_context *cic) @@ -2317,7 +2329,7 @@ static void __exit cfq_exit(void) * pending RCU callbacks */ if (elv_ioc_count_read(ioc_count)) - wait_for_completion(ioc_gone); + wait_for_completion(&all_gone); cfq_slab_kill(); } |