From: kaf24@firebug.cl.cam.ac.uk <kaf24@firebug.cl.cam.ac.uk>
Date: Wed, 14 Jun 2006 10:19:53 +0000 (+0100)
Subject: [LINUX][BLK] front: More care over device teardown.
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~15955^2~13
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https://%22%22/%22http:/www.example.com/cgi/%22https:/%22%22?a=commitdiff_plain;h=be252f5f66e6ca2a7755a004361685ec341b7089;p=xen.git

[LINUX][BLK] front: More care over device teardown.
 1. We must ensure gnttab callbacks are disabled and all work
    flushed before tearing down device state. A new gnttab interface
    call is added for this purpose.
 2. blkif_free() must check for a request_queue before deref'ing it.
Signed-off-by: Keir Fraser <keir@xensource.com>
---

diff --git a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
index 1a2156600d..20e5ad63b8 100644
--- a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
@@ -342,9 +342,21 @@ static void connect(struct blkfront_info *info)
 static void blkfront_closing(struct xenbus_device *dev)
 {
 	struct blkfront_info *info = dev->dev.driver_data;
+	unsigned long flags;
 
 	DPRINTK("blkfront_closing: %s removed\n", dev->nodename);
 
+	if (info->rq == NULL)
+		return;
+
+	spin_lock_irqsave(&blkif_io_lock, flags);
+	/* No more blkif_request(). */
+	blk_stop_queue(info->rq);
+	/* No more gnttab callback work. */
+	gnttab_cancel_free_callback(&info->callback);
+	flush_scheduled_work();
+	spin_unlock_irqrestore(&blkif_io_lock, flags);
+
 	xlvbd_del(info);
 
 	xenbus_switch_state(dev, XenbusStateClosed);
@@ -696,7 +708,12 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 	spin_lock_irq(&blkif_io_lock);
 	info->connected = suspend ?
 		BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
-	blk_stop_queue(info->rq); /* no more blkif_request() */
+	/* No more blkif_request(). */
+	if (info->rq)
+		blk_stop_queue(info->rq);
+	/* No more gnttab callback work. */
+	gnttab_cancel_free_callback(&info->callback);
+	flush_scheduled_work();
 	spin_unlock_irq(&blkif_io_lock);
 
 	/* Free resources associated with old device channel. */
diff --git a/linux-2.6-xen-sparse/drivers/xen/core/gnttab.c b/linux-2.6-xen-sparse/drivers/xen/core/gnttab.c
index f97d659f07..765dfa931f 100644
--- a/linux-2.6-xen-sparse/drivers/xen/core/gnttab.c
+++ b/linux-2.6-xen-sparse/drivers/xen/core/gnttab.c
@@ -334,6 +334,21 @@ out:
 }
 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 
+void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
+{
+	struct gnttab_free_callback **pcb;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gnttab_list_lock, flags);
+	for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
+		if (*pcb == callback) {
+			*pcb = callback->next;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&gnttab_list_lock, flags);
+}
+
 #ifndef __ia64__
 static int map_pte_fn(pte_t *pte, struct page *pmd_page,
 		      unsigned long addr, void *data)
diff --git a/linux-2.6-xen-sparse/include/xen/gnttab.h b/linux-2.6-xen-sparse/include/xen/gnttab.h
index b9207b17e1..676fca5054 100644
--- a/linux-2.6-xen-sparse/include/xen/gnttab.h
+++ b/linux-2.6-xen-sparse/include/xen/gnttab.h
@@ -100,6 +100,7 @@ void gnttab_release_grant_reference(grant_ref_t *private_head,
 
 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 				  void (*fn)(void *), void *arg, u16 count);
+void gnttab_cancel_free_callback(struct gnttab_free_callback *callback);
 
 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 				     unsigned long frame, int readonly);