Re: [Qemu-devel] [PATCH] migration/rdma: unegister fd handler

[Peter Maydell <peter.maydell@linaro.org>]

On Tue, 22 Jan 2019 at 19:08, Dr. David Alan Gilbert (git)
<dgilbert@redhat.com> wrote:
>
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Unregister the fd handler before we destroy the channel,
> otherwise we've got a race where we might land in the
> fd handler just as we're closing the device.
>
> (The race is quite data dependent, you just have to have
> the right set of devices for it to trigger).
>
> Corresponds to RH bz: https://bugzilla.redhat.com/show_bug.cgi?id=1666601
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  migration/rdma.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/migration/rdma.c b/migration/rdma.c
> index 9b2e7e10aa..54a3c11540 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -2321,6 +2321,7 @@ static void qemu_rdma_cleanup(RDMAContext *rdma)
>          rdma->connected = false;
>      }
>
> +    qemu_set_fd_handler(rdma->channel->fd, NULL, NULL, NULL);
>      g_free(rdma->dest_blocks);
>      rdma->dest_blocks = NULL;

Hi -- this patch makes coverity complain (CID 1398634),
because here we use rdma->channel without checking that it is NULL,
but later in the function we have an "if (rdma->channel)" test.
Should this code be conditional on rmda->channel being non-NULL,
or is the later test incorrect?

thanks
-- PMM