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authorJens Axboe <jens.axboe@oracle.com>2008-05-29 09:32:08 +0200
committerJens Axboe <jens.axboe@oracle.com>2008-07-03 13:21:12 +0200
commit9a11b4ed0e7c44bca7c939aa544c3c47aae40c12 (patch)
tree438312dda8a63e0704c2ddbdea958f0d729c6c7e /block/cfq-iosched.c
parentc461a973118346d5c103aaaddd62e53939fd7c67 (diff)
downloadconfigs-9a11b4ed0e7c44bca7c939aa544c3c47aae40c12.tar.gz
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>
Diffstat (limited to 'block/cfq-iosched.c')
-rw-r--r--block/cfq-iosched.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d01b411c72f..32aa3674f8a 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();
}