Re: [PATCH v5 03/15] block/nvme: Let nvme_create_queue_pair() fail gracefully

[Stefano Garzarella]

On Thu, Aug 20, 2020 at 06:58:49PM +0200, Philippe Mathieu-Daudé wrote:
> As nvme_create_queue_pair() is allowed to fail, replace the
> alloc() calls by try_alloc() to avoid aborting QEMU.
> 
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  block/nvme.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/block/nvme.c b/block/nvme.c
> index 8c30a5fee28..e1893b4e792 100644
> --- a/block/nvme.c
> +++ b/block/nvme.c
> @@ -213,14 +213,22 @@ static NVMeQueuePair 
> *nvme_create_queue_pair(BlockDriverState *bs,
>      int i, r;
>      BDRVNVMeState *s = bs->opaque;
>      Error *local_err = NULL;
> -    NVMeQueuePair *q = g_new0(NVMeQueuePair, 1);
> +    NVMeQueuePair *q;
>      uint64_t prp_list_iova;
>  
> +    q = g_try_new0(NVMeQueuePair, 1);
> +    if (!q) {
> +        return NULL;
> +    }
> +    q->prp_list_pages = qemu_try_blockalign0(bs,
> +                                          s->page_size * NVME_QUEUE_SIZE);

Here you use NVME_QUEUE_SIZE instead of NVME_NUM_REQS, is that an
intentional change?

Maybe is not an issue, sice NVME_QUEUE_SIZE is bigger than
NVME_NUM_REQS, but we should mention in the commit message.

Thanks,
Stefano

> +    if (!q->prp_list_pages) {
> +        goto fail;
> +    }
>      qemu_mutex_init(&q->lock);
>      q->s = s;
>      q->index = idx;
>      qemu_co_queue_init(&q->free_req_queue);
> -    q->prp_list_pages = qemu_blockalign0(bs, s->page_size * NVME_NUM_REQS);
>      q->completion_bh = aio_bh_new(bdrv_get_aio_context(bs),
>                                    nvme_process_completion_bh, q);
>      r = qemu_vfio_dma_map(s->vfio, q->prp_list_pages,
> -- 
> 2.26.2
> 
>