tools/testing/nvdimm: Fix fallthrough warning

[linux-2.6-microblaze.git] / block / bfq-iosched.c

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 586fcfe..b33be92 100644 (file)
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -1924,12 +1924,13 @@ static void bfq_add_request(struct request *rq)
                 * confirmed no later than during the next
                 * I/O-plugging interval for bfqq.
                 */
-               if (!bfq_bfqq_has_short_ttime(bfqq) &&
+               if (bfqd->last_completed_rq_bfqq &&
+                   !bfq_bfqq_has_short_ttime(bfqq) &&
                    ktime_get_ns() - bfqd->last_completion <
                    200 * NSEC_PER_USEC) {
                        if (bfqd->last_completed_rq_bfqq != bfqq &&
-                                  bfqd->last_completed_rq_bfqq !=
-                                  bfqq->waker_bfqq) {
+                           bfqd->last_completed_rq_bfqq !=
+                           bfqq->waker_bfqq) {
                                /*
                                 * First synchronization detected with
                                 * a candidate waker queue, or with a
@@ -2250,9 +2251,14 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
            blk_rq_pos(container_of(rb_prev(&req->rb_node),
                                    struct request, rb_node))) {
                struct bfq_queue *bfqq = bfq_init_rq(req);
-               struct bfq_data *bfqd = bfqq->bfqd;
+               struct bfq_data *bfqd;
                struct request *prev, *next_rq;
 
+               if (!bfqq)
+                       return;
+
+               bfqd = bfqq->bfqd;
+
                /* Reposition request in its sort_list */
                elv_rb_del(&bfqq->sort_list, req);
                elv_rb_add(&bfqq->sort_list, req);
@@ -2299,6 +2305,9 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
        struct bfq_queue *bfqq = bfq_init_rq(rq),
                *next_bfqq = bfq_init_rq(next);
 
+       if (!bfqq)
+               return;
+
        /*
         * If next and rq belong to the same bfq_queue and next is older
         * than rq, then reposition rq in the fifo (by substituting next
@@ -4764,6 +4773,8 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
  */
 void bfq_put_queue(struct bfq_queue *bfqq)
 {
+       struct bfq_queue *item;
+       struct hlist_node *n;
 #ifdef CONFIG_BFQ_GROUP_IOSCHED
        struct bfq_group *bfqg = bfqq_group(bfqq);
 #endif
@@ -4808,6 +4819,36 @@ void bfq_put_queue(struct bfq_queue *bfqq)
                        bfqq->bfqd->burst_size--;
        }
 
+       /*
+        * bfqq does not exist any longer, so it cannot be woken by
+        * any other queue, and cannot wake any other queue. Then bfqq
+        * must be removed from the woken list of its possible waker
+        * queue, and all queues in the woken list of bfqq must stop
+        * having a waker queue. Strictly speaking, these updates
+        * should be performed when bfqq remains with no I/O source
+        * attached to it, which happens before bfqq gets freed. In
+        * particular, this happens when the last process associated
+        * with bfqq exits or gets associated with a different
+        * queue. However, both events lead to bfqq being freed soon,
+        * and dangling references would come out only after bfqq gets
+        * freed. So these updates are done here, as a simple and safe
+        * way to handle all cases.
+        */
+       /* remove bfqq from woken list */
+       if (!hlist_unhashed(&bfqq->woken_list_node))
+               hlist_del_init(&bfqq->woken_list_node);
+
+       /* reset waker for all queues in woken list */
+       hlist_for_each_entry_safe(item, n, &bfqq->woken_list,
+                                 woken_list_node) {
+               item->waker_bfqq = NULL;
+               bfq_clear_bfqq_has_waker(item);
+               hlist_del_init(&item->woken_list_node);
+       }
+
+       if (bfqq->bfqd && bfqq->bfqd->last_completed_rq_bfqq == bfqq)
+               bfqq->bfqd->last_completed_rq_bfqq = NULL;
+
        kmem_cache_free(bfq_pool, bfqq);
 #ifdef CONFIG_BFQ_GROUP_IOSCHED
        bfqg_and_blkg_put(bfqg);
@@ -4835,9 +4876,6 @@ static void bfq_put_cooperator(struct bfq_queue *bfqq)
 
 static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
 {
-       struct bfq_queue *item;
-       struct hlist_node *n;
-
        if (bfqq == bfqd->in_service_queue) {
                __bfq_bfqq_expire(bfqd, bfqq, BFQQE_BUDGET_TIMEOUT);
                bfq_schedule_dispatch(bfqd);
@@ -4847,18 +4885,6 @@ static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
 
        bfq_put_cooperator(bfqq);
 
-       /* remove bfqq from woken list */
-       if (!hlist_unhashed(&bfqq->woken_list_node))
-               hlist_del_init(&bfqq->woken_list_node);
-
-       /* reset waker for all queues in woken list */
-       hlist_for_each_entry_safe(item, n, &bfqq->woken_list,
-                                 woken_list_node) {
-               item->waker_bfqq = NULL;
-               bfq_clear_bfqq_has_waker(item);
-               hlist_del_init(&item->woken_list_node);
-       }
-
        bfq_put_queue(bfqq); /* release process reference */
 }
 
@@ -5436,12 +5462,12 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 
        spin_lock_irq(&bfqd->lock);
        bfqq = bfq_init_rq(rq);
-       if (at_head || blk_rq_is_passthrough(rq)) {
+       if (!bfqq || at_head || blk_rq_is_passthrough(rq)) {
                if (at_head)
                        list_add(&rq->queuelist, &bfqd->dispatch);
                else
                        list_add_tail(&rq->queuelist, &bfqd->dispatch);
-       } else { /* bfqq is assumed to be non null here */
+       } else {
                idle_timer_disabled = __bfq_insert_request(bfqd, rq);
                /*
                 * Update bfqq, because, if a queue merge has occurred