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

[Stefano Garzarella]

On Fri, Aug 21, 2020 at 03:36:47PM +0200, Philippe Mathieu-Daudé wrote:
> On 8/21/20 11:44 AM, Stefano Garzarella wrote:
> > 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?
> 
> No... Thanks for spotting this, I missed it because git didn't
> emit any warning while rebasing on top of "block/nvme: support nested
> aio_poll".
> This value has been changed in 1086e95da17 ("block/nvme: switch to a
> NVMeRequest freelist").
> 
> Good catch!
> I'll respin (after reviewing the 'nested aio_poll' changes).

Cool, with that fixed the patch LGTM:

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

> 
> > 
> > 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
> >>
> >>
> > 
>