linux-kernel - [PATCH] block: xen-blkback: don't get/put blkif ref for each queue

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Date:   Mon, 26 Sep 2016 15:36:24 +0800
From:   Bob Liu <bob.liu@...cle.com>
To:     xen-devel@...ts.xenproject.org
Cc:     roger.pau@...rix.com, konrad.wilk@...cle.com,
        linux-kernel@...r.kernel.org, Bob Liu <bob.liu@...cle.com>
Subject: [PATCH] block: xen-blkback: don't get/put blkif ref for each queue

xen_blkif_get/put() for each queue is useless, and introduces a bug:

If there is I/O inflight when removing device, xen_blkif_disconnect() will
return -EBUSY and xen_blkif_put() not be called.
Which means the references are leaked, then even if I/O completed, the
xen_blkif_put() won't call xen_blkif_deferred_free() to free resources anymore.

Signed-off-by: Bob Liu <bob.liu@...cle.com>
---
 drivers/block/xen-blkback/xenbus.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 3cc6d1d..2e1bb6d 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -159,7 +159,6 @@ static int xen_blkif_alloc_rings(struct xen_blkif *blkif)
 		init_waitqueue_head(&ring->shutdown_wq);
 		ring->blkif = blkif;
 		ring->st_print = jiffies;
-		xen_blkif_get(blkif);
 	}
 
 	return 0;
@@ -296,7 +295,6 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif)
 		BUG_ON(ring->free_pages_num != 0);
 		BUG_ON(ring->persistent_gnt_c != 0);
 		WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
-		xen_blkif_put(blkif);
 	}
 	blkif->nr_ring_pages = 0;
 	/*
-- 
1.7.10.4