Re: [Qemu-devel] [Qemu-block] [PATCH] nvme: Set number of queues later in nvme_init()

[Maxim Levitsky <mlevitsk@redhat.com>]

On Wed, 2019-07-10 at 17:34 +0200, Philippe Mathieu-Daudé wrote:
> On 7/10/19 4:57 PM, Michal Privoznik wrote:
> > When creating the admin queue in nvme_init() the variable that
> > holds the number of queues created is modified before actual
> > queue creation. This is a problem because if creating the queue
> > fails then the variable is left in inconsistent state. This was
> > actually observed when I tried to hotplug a nvme disk. The
> > control got to nvme_file_open() which called nvme_init() which
> > failed and thus nvme_close() was called which in turn called
> > nvme_free_queue_pair() with queue being NULL. This lead to an
> > instant crash:
> > 
> >   #0  0x000055d9507ec211 in nvme_free_queue_pair (bs=0x55d952ddb880, q=0x0) at block/nvme.c:164
> >   #1  0x000055d9507ee180 in nvme_close (bs=0x55d952ddb880) at block/nvme.c:729
> >   #2  0x000055d9507ee3d5 in nvme_file_open (bs=0x55d952ddb880, options=0x55d952bb1410, flags=147456, errp=0x7ffd8e19e200) at block/nvme.c:781
> >   #3  0x000055d9507629f3 in bdrv_open_driver (bs=0x55d952ddb880, drv=0x55d95109c1e0 <bdrv_nvme>, node_name=0x0, options=0x55d952bb1410, open_flags=147456, errp=0x7ffd8e19e310) at block.c:1291
> >   #4  0x000055d9507633d6 in bdrv_open_common (bs=0x55d952ddb880, file=0x0, options=0x55d952bb1410, errp=0x7ffd8e19e310) at block.c:1551
> >   #5  0x000055d950766881 in bdrv_open_inherit (filename=0x0, reference=0x0, options=0x55d952bb1410, flags=32768, parent=0x55d9538ce420, child_role=0x55d950eaade0 <child_file>, errp=0x7ffd8e19e510)
> > at block.c:3063
> >   #6  0x000055d950765ae4 in bdrv_open_child_bs (filename=0x0, options=0x55d9541cdff0, bdref_key=0x55d950af33aa "file", parent=0x55d9538ce420, child_role=0x55d950eaade0 <child_file>,
> > allow_none=true, errp=0x7ffd8e19e510) at block.c:2712
> >   #7  0x000055d950766633 in bdrv_open_inherit (filename=0x0, reference=0x0, options=0x55d9541cdff0, flags=0, parent=0x0, child_role=0x0, errp=0x7ffd8e19e908) at block.c:3011
> >   #8  0x000055d950766dba in bdrv_open (filename=0x0, reference=0x0, options=0x55d953d00390, flags=0, errp=0x7ffd8e19e908) at block.c:3156
> >   #9  0x000055d9507cb635 in blk_new_open (filename=0x0, reference=0x0, options=0x55d953d00390, flags=0, errp=0x7ffd8e19e908) at block/block-backend.c:389
> >   #10 0x000055d950465ec5 in blockdev_init (file=0x0, bs_opts=0x55d953d00390, errp=0x7ffd8e19e908) at blockdev.c:602
> > 
> 
> Fixes: bdd6a90a9e5
> 
> > Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
> 
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> 
> > ---
> >  block/nvme.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/block/nvme.c b/block/nvme.c
> > index 73ed5fa75f..9896b7f7c6 100644
> > --- a/block/nvme.c
> > +++ b/block/nvme.c
> > @@ -613,12 +613,12 @@ static int nvme_init(BlockDriverState *bs, const char *device, int namespace,
> >  
> >      /* Set up admin queue. */
> >      s->queues = g_new(NVMeQueuePair *, 1);
> > -    s->nr_queues = 1;
> >      s->queues[0] = nvme_create_queue_pair(bs, 0, NVME_QUEUE_SIZE, errp);
> >      if (!s->queues[0]) {
> >          ret = -EINVAL;
> >          goto out;
> >      }
> > +    s->nr_queues = 1;
> >      QEMU_BUILD_BUG_ON(NVME_QUEUE_SIZE & 0xF000);
> >      s->regs->aqa = cpu_to_le32((NVME_QUEUE_SIZE << 16) | NVME_QUEUE_SIZE);
> >      s->regs->asq = cpu_to_le64(s->queues[0]->sq.iova);
> > 
> 
> 


Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Best regards,
	Maxim Levitsky