[PATCH] cfq-iosched: fixup locking and ->queue_list list management

- Drop cic from the list when seen as dead.
- Fixup the locking, just use a simple spinlock.

Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 13 insertions, 12 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 2540dfaa3e38..11ce6aaf1bd0 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -33,7 +33,7 @@ static int cfq_slice_idle = HZ / 70;
 
 #define CFQ_KEY_ASYNC           (0)
 
-static DEFINE_RWLOCK(cfq_exit_lock);
+static DEFINE_SPINLOCK(cfq_exit_lock);
 
 /*
  * for the hash of cfqq inside the cfqd
@@ -1284,7 +1284,7 @@ static void cfq_exit_io_context(struct io_context *ioc)
         /*
          * put the reference this task is holding to the various queues
          */
-        read_lock_irqsave(&cfq_exit_lock, flags);
+        spin_lock_irqsave(&cfq_exit_lock, flags);
 
         n = rb_first(&ioc->cic_root);
         while (n != NULL) {
@@ -1294,7 +1294,7 @@ static void cfq_exit_io_context(struct io_context *ioc)
                 n = rb_next(n);
         }
 
-        read_unlock_irqrestore(&cfq_exit_lock, flags);
+        spin_unlock_irqrestore(&cfq_exit_lock, flags);
 }
 
 static struct cfq_io_context *
@@ -1400,17 +1400,17 @@ static int cfq_ioc_set_ioprio(struct io_context *ioc, unsigned int ioprio)
         struct cfq_io_context *cic;
         struct rb_node *n;
 
-        write_lock(&cfq_exit_lock);
+        spin_lock(&cfq_exit_lock);
 
         n = rb_first(&ioc->cic_root);
         while (n != NULL) {
                 cic = rb_entry(n, struct cfq_io_context, rb_node);
- 
+
                 changed_ioprio(cic);
                 n = rb_next(n);
         }
 
-        write_unlock(&cfq_exit_lock);
+        spin_unlock(&cfq_exit_lock);
 
         return 0;
 }
@@ -1475,9 +1475,10 @@ out:
 static void
 cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic)
 {
-        read_lock(&cfq_exit_lock);
+        spin_lock(&cfq_exit_lock);
         rb_erase(&cic->rb_node, &ioc->cic_root);
-        read_unlock(&cfq_exit_lock);
+        list_del_init(&cic->queue_list);
+        spin_unlock(&cfq_exit_lock);
         kmem_cache_free(cfq_ioc_pool, cic);
         atomic_dec(&ioc_count);
 }
@@ -1545,11 +1546,11 @@ restart:
                         BUG();
         }
 
-        read_lock(&cfq_exit_lock);
+        spin_lock(&cfq_exit_lock);
         rb_link_node(&cic->rb_node, parent, p);
         rb_insert_color(&cic->rb_node, &ioc->cic_root);
         list_add(&cic->queue_list, &cfqd->cic_list);
-        read_unlock(&cfq_exit_lock);
+        spin_unlock(&cfq_exit_lock);
 }
 
 /*
@@ -2187,7 +2188,7 @@ static void cfq_exit_queue(elevator_t *e)
 
         cfq_shutdown_timer_wq(cfqd);
 
-        write_lock(&cfq_exit_lock);
+        spin_lock(&cfq_exit_lock);
         spin_lock_irq(q->queue_lock);
 
         if (cfqd->active_queue)
@@ -2210,7 +2211,7 @@ static void cfq_exit_queue(elevator_t *e)
         }
 
         spin_unlock_irq(q->queue_lock);
-        write_unlock(&cfq_exit_lock);
+        spin_unlock(&cfq_exit_lock);
 
         cfq_shutdown_timer_wq(cfqd);