aoe: Avoid flush_scheduled_work() usage

Flushing system-wide workqueues is dangerous and will be forbidden.
Replace system_wq with local aoe_wq.

Link: https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jpSigned-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/abb37616-eec9-2794-e21e-7c623085d987@I-love.SAKURA.ne.jpSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/aoe/aoe.h

@@ -244,3 +244,5 @@ void aoenet_exit(void);
 void aoenet_xmit(struct sk_buff_head *);
 int is_aoe_netif(struct net_device *ifp);
 int set_aoe_iflist(const char __user *str, size_t size);
+
+extern struct workqueue_struct *aoe_wq;

drivers/block/aoe/aoeblk.c

@@ -435,7 +435,7 @@ aoeblk_gdalloc(void *vp)
 err:
 	spin_lock_irqsave(&d->lock, flags);
 	d->flags &= ~DEVFL_GD_NOW;
-	schedule_work(&d->work);
+	queue_work(aoe_wq, &d->work);
 	spin_unlock_irqrestore(&d->lock, flags);
 }
 

drivers/block/aoe/aoecmd.c

@@ -968,7 +968,7 @@ ataid_complete(struct aoedev *d, struct aoetgt *t, unsigned char *id)
 		d->flags |= DEVFL_NEWSIZE;
 	else
 		d->flags |= DEVFL_GDALLOC;
-	schedule_work(&d->work);
+	queue_work(aoe_wq, &d->work);
 }
 
 static void

drivers/block/aoe/aoedev.c

@@ -321,7 +321,7 @@ flush(const char __user *str, size_t cnt, int exiting)
 			specified = 1;
 	}
 
-	flush_scheduled_work();
+	flush_workqueue(aoe_wq);
 	/* pass one: do aoedev_downdev, which might sleep */
 restart1:
 	spin_lock_irqsave(&devlist_lock, flags);
@@ -520,7 +520,7 @@ freetgt(struct aoedev *d, struct aoetgt *t)
 void
 aoedev_exit(void)
 {
-	flush_scheduled_work();
+	flush_workqueue(aoe_wq);
 	flush(NULL, 0, EXITING);
 }
 

drivers/block/aoe/aoemain.c

@@ -16,6 +16,7 @@ MODULE_DESCRIPTION("AoE block/char driver for 2.6.2 and newer 2.6 kernels");
 MODULE_VERSION(VERSION);
 
 static struct timer_list timer;
+struct workqueue_struct *aoe_wq;
 
 static void discover_timer(struct timer_list *t)
 {
@@ -35,6 +36,7 @@ aoe_exit(void)
 	aoechr_exit();
 	aoedev_exit();
 	aoeblk_exit();		/* free cache after de-allocating bufs */
+	destroy_workqueue(aoe_wq);
 }
 
 static int __init
@@ -42,9 +44,13 @@ aoe_init(void)
 {
 	int ret;
 
+	aoe_wq = alloc_workqueue("aoe_wq", 0, 0);
+	if (!aoe_wq)
+		return -ENOMEM;
+
 	ret = aoedev_init();
 	if (ret)
-		return ret;
+		goto dev_fail;
 	ret = aoechr_init();
 	if (ret)
 		goto chr_fail;
@@ -77,6 +83,8 @@ aoe_init(void)
 	aoechr_exit();
  chr_fail:
 	aoedev_exit();
+ dev_fail:
+	destroy_workqueue(aoe_wq);
 
 	printk(KERN_INFO "aoe: initialisation failure.\n");
 	return ret;