[PATCH] fix cfq_get_queue()/ioprio_set(2) races
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3cd985b..2949920 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -296,6 +296,7 @@
static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *);
static void cfq_put_cfqd(struct cfq_data *cfqd);
+static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk, gfp_t gfp_mask);
#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
@@ -1365,8 +1366,13 @@
spin_lock(cfqd->queue->queue_lock);
cfqq = cic->cfqq[ASYNC];
if (cfqq) {
- cfq_mark_cfqq_prio_changed(cfqq);
- cfq_init_prio_data(cfqq);
+ struct cfq_queue *new_cfqq;
+ new_cfqq = cfq_get_queue(cfqd, CFQ_KEY_ASYNC,
+ cic->ioc->task, GFP_ATOMIC);
+ if (new_cfqq) {
+ cic->cfqq[ASYNC] = new_cfqq;
+ cfq_put_queue(cfqq);
+ }
}
cfqq = cic->cfqq[SYNC];
if (cfqq) {
@@ -1399,13 +1405,15 @@
}
static struct cfq_queue *
-cfq_get_queue(struct cfq_data *cfqd, unsigned int key, unsigned short ioprio,
+cfq_get_queue(struct cfq_data *cfqd, unsigned int key, struct task_struct *tsk,
gfp_t gfp_mask)
{
const int hashval = hash_long(key, CFQ_QHASH_SHIFT);
struct cfq_queue *cfqq, *new_cfqq = NULL;
+ unsigned short ioprio;
retry:
+ ioprio = tsk->ioprio;
cfqq = __cfq_find_cfq_hash(cfqd, key, ioprio, hashval);
if (!cfqq) {
@@ -1982,7 +1990,7 @@
goto queue_fail;
if (!cic->cfqq[is_sync]) {
- cfqq = cfq_get_queue(cfqd, key, tsk->ioprio, gfp_mask);
+ cfqq = cfq_get_queue(cfqd, key, tsk, gfp_mask);
if (!cfqq)
goto queue_fail;