linux-kernel - [PATCH 4.4 12/17] xen/blkfront: fix bug in backported patch

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Message-Id: <20211227151316.349920128@linuxfoundation.org>
Date:   Mon, 27 Dec 2021 16:27:07 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "xen-devel@...ts.xenproject.org, Juergen Gross" <jgross@...e.com>,
        Juergen Gross <jgross@...e.com>
Subject: [PATCH 4.4 12/17] xen/blkfront: fix bug in backported patch

From: Juergen Gross <jgross@...e.com>

The backport of commit 8f5a695d99000fc ("xen/blkfront: don't take local
copy of a request from the ring page") to stable 4.4 kernel introduced
a bug when adding the needed blkif_ring_get_request() function, as
info->ring.req_prod_pvt was incremented twice now.

Fix that be deleting the now superfluous increments after calling that
function.

Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/block/xen-blkfront.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -493,8 +493,6 @@ static int blkif_queue_discard_req(struc
 	else
 		ring_req->u.discard.flag = 0;
 
-	info->ring.req_prod_pvt++;
-
 	/* Copy the request to the ring page. */
 	*final_ring_req = *ring_req;
 	info->shadow[id].inflight = true;
@@ -711,8 +709,6 @@ static int blkif_queue_rw_req(struct req
 	if (setup.segments)
 		kunmap_atomic(setup.segments);
 
-	info->ring.req_prod_pvt++;
-
 	/* Copy request(s) to the ring page. */
 	*final_ring_req = *ring_req;
 	info->shadow[id].inflight = true;