Re: [PATCH] hw/nvme: fix control flow statement

[Keith Busch]

On Fri, Apr 15, 2022 at 10:27:21PM +0300, Dmitry Tikhov wrote:
> Since there is no else after nvme_dsm_cb invocation, metadata associated
> with non-zero block range is currently zeroed. Also this behaviour leads
> to segfault since we schedule iocb->bh two times. First when entering
> nvme_dsm_cb with iocb->idx == iocb->nr and second on call stack unwinding
> by calling blk_aio_pwrite_zeroes and subsequent nvme_dsm_cb callback
> because of missing else statement.
> 
> Signed-off-by: Dmitry Tikhov <d.tihov@yadro.com>
> ---
>  hw/nvme/ctrl.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
> index 03760ddeae..7ebd2aa326 100644
> --- a/hw/nvme/ctrl.c
> +++ b/hw/nvme/ctrl.c
> @@ -2372,11 +2372,12 @@ static void nvme_dsm_md_cb(void *opaque, int ret)
>          }
>  
>          nvme_dsm_cb(iocb, 0);
> +    } else {
> +        iocb->aiocb = blk_aio_pwrite_zeroes(ns->blkconf.blk, nvme_moff(ns, 
> slba),
> +                                            nvme_m2b(ns, nlb), 
> BDRV_REQ_MAY_UNMAP,
> +                                            nvme_dsm_cb, iocb);
>      }

Instead of the 'else', just insert an early 'return;' after nvme_dsm_cb() like
the earlier condition above here. Otherwise, looks good, and thanks for the
fix.