Re: [PATCH 4/4] libvduse: Check the return value of some ioctls

[Markus Armbruster]

Yongji Xie <xieyongji@bytedance.com> writes:

> On Wed, Jun 29, 2022 at 5:41 PM Markus Armbruster <armbru@redhat.com> wrote:
>>
>> Xie Yongji <xieyongji@bytedance.com> writes:
>>
>> > Coverity pointed out (CID 1490222, 1490227) that we called
>> > ioctl somewhere without checking the return value. This
>> > patch fixes these issues.
>> >
>> > Fixes: Coverity CID 1490222, 1490227
>> > Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
>> > ---
>> >  subprojects/libvduse/libvduse.c | 10 ++++++++--
>> >  1 file changed, 8 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/subprojects/libvduse/libvduse.c 
>> > b/subprojects/libvduse/libvduse.c
>> > index 1a5981445c..bf7302c60a 100644
>> > --- a/subprojects/libvduse/libvduse.c
>> > +++ b/subprojects/libvduse/libvduse.c
>> > @@ -947,7 +947,10 @@ static void vduse_queue_disable(VduseVirtq *vq)
>> >
>> >      eventfd.index = vq->index;
>> >      eventfd.fd = VDUSE_EVENTFD_DEASSIGN;
>> > -    ioctl(dev->fd, VDUSE_VQ_SETUP_KICKFD, &eventfd);
>> > +    if (ioctl(dev->fd, VDUSE_VQ_SETUP_KICKFD, &eventfd)) {
>> > +        fprintf(stderr, "Failed to disable eventfd for vq[%d]: %s\n",
>> > +                vq->index, strerror(errno));
>> > +    }
>> >      close(vq->fd);
>> >
>> >      assert(vq->inuse == 0);
>> > @@ -1337,7 +1340,10 @@ VduseDev *vduse_dev_create(const char *name, 
>> > uint32_t device_id,
>> >
>> >      return dev;
>> >  err:
>> > -    ioctl(ctrl_fd, VDUSE_DESTROY_DEV, name);
>> > +    if (ioctl(ctrl_fd, VDUSE_DESTROY_DEV, name)) {
>> > +        fprintf(stderr, "Failed to destroy vduse device %s: %s\n",
>> > +                name, strerror(errno));
>> > +    }
>> >  err_dev:
>> >      close(ctrl_fd);
>> >  err_ctrl:
>>
>> Both errors are during cleanup that can't fail.  The program continues
>> as if they didn't happen.  Does the user need to know?
>>
>
> So I printed some error messages. I didn't find any other good way to
> notify the users.

I can think of another way, either.  But my question wasn't about "how",
it was about "why".  The answer depends on the impact of these errors.
Which I can't judge.  Can you?