linux-kernel - [PATCH][next] vhost: only return early if ret indicates an error or no iovecs have been processed

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Message-Id: <20190219135713.10426-1-colin.king@canonical.com>
Date:   Tue, 19 Feb 2019 13:57:13 +0000
From:   Colin King <colin.king@...onical.com>
To:     "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] vhost: only return early if ret indicates an error or no iovecs have been processed

From: Colin Ian King <colin.king@...onical.com>

Currently the loop that calls log_write_hva on each iovec is never
executed because of an incorrect error check on the return from the
call to translate_desc.  The check should be checking for a -ve error
return and because it makes no sense to iterate over zero items, the
checks should also check for zero too.

Detected by CoverityScan, CID#1476969 ("Logically dead code")

Fixes: cc5e71075947 ("vhost: log dirty page correctly")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/vhost/vhost.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 24a129fcdd61..a9a1709a859a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1788,7 +1788,7 @@ static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
 
 	ret = translate_desc(vq, (uintptr_t)vq->used + used_offset,
 			     len, iov, 64, VHOST_ACCESS_WO);
-	if (ret)
+	if (ret <= 0)
 		return ret;
 
 	for (i = 0; i < ret; i++) {
-- 
2.20.1