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Re: [PATCH] hw/virtio/vhost-shadow-virtqueue: Silence GCC error "maybe-u
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From: |
Philippe Mathieu-Daudé |
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Subject: |
Re: [PATCH] hw/virtio/vhost-shadow-virtqueue: Silence GCC error "maybe-uninitialized" |
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Date: |
Tue, 6 Sep 2022 19:52:24 +0200 |
On Tue, Sep 6, 2022 at 7:12 PM Bernhard Beschow <shentey@gmail.com> wrote:
>
> GCC issues a false positive warning, resulting in build failure with -Werror:
>
> In file included from /usr/include/glib-2.0/glib.h:114,
> from
> /home/zcone-pisint/Projects/qemu/src/include/glib-compat.h:32,
> from
> /home/zcone-pisint/Projects/qemu/src/include/qemu/osdep.h:144,
> from ../src/hw/virtio/vhost-shadow-virtqueue.c:10:
> In function ‘g_autoptr_cleanup_generic_gfree’,
> inlined from ‘vhost_handle_guest_kick’ at
> ../src/hw/virtio/vhost-shadow-virtqueue.c:292:42:
> /usr/include/glib-2.0/glib/glib-autocleanups.h:28:3: error: ‘elem’ may be
> used uninitialized [-Werror=maybe-uninitialized]
> 28 | g_free (*pp);
> | ^~~~~~~~~~~~
> ../src/hw/virtio/vhost-shadow-virtqueue.c: In function
> ‘vhost_handle_guest_kick’:
> ../src/hw/virtio/vhost-shadow-virtqueue.c:292:42: note: ‘elem’ was declared
> here
> 292 | g_autofree VirtQueueElement *elem;
> | ^~~~
> cc1: all warnings being treated as errors
>
> There is actually no problem since "elem" is initialized in both branches.
> Silence the warning by initializig it with "NULL".
Could you amend the first line of `gcc --version`?
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Fixes: 9c2ab2f1ec333be8614cc12272d4b91960704dbe ("vhost: stop transfer elem
> ownership in vhost_handle_guest_kick")
> Signed-off-by: Bernhard Beschow <shentey@gmail.com>
> ---
> hw/virtio/vhost-shadow-virtqueue.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> b/hw/virtio/vhost-shadow-virtqueue.c
> index e8e5bbc368..596d4434d2 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -289,7 +289,7 @@ static void vhost_handle_guest_kick(VhostShadowVirtqueue
> *svq)
> virtio_queue_set_notification(svq->vq, false);
>
> while (true) {
> - g_autofree VirtQueueElement *elem;
> + g_autofree VirtQueueElement *elem = NULL;
> int r;
>
> if (svq->next_guest_avail_elem) {
> --
> 2.37.3
>
>