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authorFabio Checconi <fabio@gandalf.sssup.i>2008-04-02 14:31:02 +0200
committerJens Axboe <jens.axboe@oracle.com>2008-04-02 15:42:20 +0200
commit34e6bbf23c8f43e8713d9bd092680f1660494b4a (patch)
tree908e97ac3d43882cb42bf57c41926852d3bc2f6e /block/cfq-iosched.c
parent00d61e3e8c12d5f395b167856d2b3c430816afb0 (diff)
downloadconfigs-34e6bbf23c8f43e8713d9bd092680f1660494b4a.tar.gz
cfq-iosched: fix rcu freeing of cfq io contexts
SLAB_DESTROY_BY_RCU is not a direct substitute for normal call_rcu() freeing, since it'll page freeing but NOT object freeing. So change cfq to do the freeing on its own. Signed-off-by: Fabio Checconi <fabio@gandalf.sssup.it> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/cfq-iosched.c')
-rw-r--r--block/cfq-iosched.c57
1 files changed, 27 insertions, 30 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 0f962ecae91..f26da2bfcc1 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1143,24 +1143,37 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
}
/*
- * Call func for each cic attached to this ioc. Returns number of cic's seen.
+ * Call func for each cic attached to this ioc.
*/
-static unsigned int
+static void
call_for_each_cic(struct io_context *ioc,
void (*func)(struct io_context *, struct cfq_io_context *))
{
struct cfq_io_context *cic;
struct hlist_node *n;
- int called = 0;
rcu_read_lock();
- hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) {
+ hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
func(ioc, cic);
- called++;
- }
rcu_read_unlock();
+}
+
+static void cfq_cic_free_rcu(struct rcu_head *head)
+{
+ struct cfq_io_context *cic;
+
+ cic = container_of(head, struct cfq_io_context, rcu_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);
+}
- return called;
+static void cfq_cic_free(struct cfq_io_context *cic)
+{
+ call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
}
static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
@@ -1174,24 +1187,18 @@ static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
hlist_del_rcu(&cic->cic_list);
spin_unlock_irqrestore(&ioc->lock, flags);
- kmem_cache_free(cfq_ioc_pool, cic);
+ cfq_cic_free(cic);
}
static void cfq_free_io_context(struct io_context *ioc)
{
- int freed;
-
/*
- * ioc->refcount is zero here, so no more cic's are allowed to be
- * linked into this ioc. So it should be ok to iterate over the known
- * list, we will see all cic's since no new ones are added.
+ * ioc->refcount is zero here, or we are called from elv_unregister(),
+ * so no more cic's are allowed to be linked into this ioc. So it
+ * should be ok to iterate over the known list, we will see all cic's
+ * since no new ones are added.
*/
- freed = call_for_each_cic(ioc, cic_free_func);
-
- elv_ioc_count_mod(ioc_count, -freed);
-
- if (ioc_gone && !elv_ioc_count_read(ioc_count))
- complete(ioc_gone);
+ call_for_each_cic(ioc, cic_free_func);
}
static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
@@ -1458,15 +1465,6 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
return cfqq;
}
-static void cfq_cic_free(struct cfq_io_context *cic)
-{
- 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);
-}
-
/*
* We drop cfq io contexts lazily, so we may find a dead one.
*/
@@ -2138,7 +2136,7 @@ static int __init cfq_slab_setup(void)
if (!cfq_pool)
goto fail;
- cfq_ioc_pool = KMEM_CACHE(cfq_io_context, SLAB_DESTROY_BY_RCU);
+ cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
if (!cfq_ioc_pool)
goto fail;
@@ -2286,7 +2284,6 @@ static void __exit cfq_exit(void)
smp_wmb();
if (elv_ioc_count_read(ioc_count))
wait_for_completion(ioc_gone);
- synchronize_rcu();
cfq_slab_kill();
}