linux-kernel - [PATCH RFC 2/2] xen/blkback: Free resources if connect

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Date:	Wed, 25 Nov 2015 14:35:11 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	roger.pau@...rix.com, jonathan.davies@...rix.com,
	david.vrabel@...rix.com, linux-kernel@...r.kernel.org,
	jgross@...e.com, xen-devel@...ts.xenproject.org, bob.liu@...cle.com
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH RFC 2/2] xen/blkback: Free resources if connect_ring failed.

With the multi-queue support we could fail at setting up
some of the rings and fail the connection. That meant that
all resources tied to rings[0..n-1] (where n is the ring
that failed to be setup). Eventually the frontend will switch
to the states and we will call xen_blkif_disconnect.

However we do not want to be at the mercy of the frontend
deciding when to change states. This allows us to do the
cleanup right away and freeing resources.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
 drivers/block/xen-blkback/xenbus.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index ca3a414..c92b358 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -749,8 +749,14 @@ static void frontend_changed(struct xenbus_device *dev,
 		}
 
 		err = connect_ring(be);
-		if (err)
+		if (err) {
+			/*
+			 * Clean up so that memory resources can be used by
+			 * other devices. connect_ring reported already error.
+			 */
+			xen_blkif_disconnect(be->blkif);
 			break;
+		}
 		xen_update_blkif_status(be->blkif);
 		break;
 
-- 
2.5.0

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