linux-kernel - [PATCH 5.15 104/106] virtio-pci: Remove wrong address verification in vp_del

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Date:   Mon, 20 Jun 2022 14:52:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Christophe de Dinechin <dinechin@...hat.com>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 5.15 104/106] virtio-pci: Remove wrong address verification in vp_del_vqs()

From: Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>

commit 7e415282b41bf0d15c6e0fe268f822d9b083f2f7 upstream.

GCC 12 enhanced -Waddress when comparing array address to null [0],
which warns:

    drivers/virtio/virtio_pci_common.c: In function ‘vp_del_vqs’:
    drivers/virtio/virtio_pci_common.c:257:29: warning: the comparison will always evaluate as ‘true’ for the pointer operand in ‘vp_dev->msix_affinity_masks + (sizetype)((long unsigned int)i * 256)’ must not be NULL [-Waddress]
      257 |                         if (vp_dev->msix_affinity_masks[i])
          |                             ^~~~~~

In fact, the verification is comparing the result of a pointer
arithmetic, the address "msix_affinity_masks + i", which will always
evaluate to true.

Under the hood, free_cpumask_var() calls kfree(), which is safe to pass
NULL, not requiring non-null verification.  So remove the verification
to make compiler happy (happy compiler, happy life).

[0] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102103

Signed-off-by: Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
Message-Id: <20220415023002.49805-1-muriloo@...ux.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
Acked-by: Christophe de Dinechin <dinechin@...hat.com>
Cc: Sudip Mukherjee <sudipm.mukherjee@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/virtio/virtio_pci_common.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -254,8 +254,7 @@ void vp_del_vqs(struct virtio_device *vd
 
 	if (vp_dev->msix_affinity_masks) {
 		for (i = 0; i < vp_dev->msix_vectors; i++)
-			if (vp_dev->msix_affinity_masks[i])
-				free_cpumask_var(vp_dev->msix_affinity_masks[i]);
+			free_cpumask_var(vp_dev->msix_affinity_masks[i]);
 	}
 
 	if (vp_dev->msix_enabled) {