linux-kernel - Re: [PATCH] [v2] rbd: avoid Wreturn-type warnings

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Date:   Wed, 4 Apr 2018 15:10:26 +0200
From:   Ilya Dryomov <idryomov@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Sage Weil <sage@...hat.com>, Alex Elder <elder@...nel.org>,
        Jens Axboe <axboe@...nel.dk>,
        Jason Dillaman <dillaman@...hat.com>,
        Ceph Development <ceph-devel@...r.kernel.org>,
        linux-block <linux-block@...r.kernel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v2] rbd: avoid Wreturn-type warnings

On Wed, Apr 4, 2018 at 2:53 PM, Arnd Bergmann <arnd@...db.de> wrote:
> A new set of warnings appeared in next-20180403 in some configurations
> when gcc cannot see that rbd_assert(0) leads to an unreachable code
> path:
>
> drivers/block/rbd.c: In function 'rbd_img_is_write':
> drivers/block/rbd.c:1397:1: error: control reaches end of non-void function [-Werror=return-type]
> drivers/block/rbd.c: In function '__rbd_obj_handle_request':
> drivers/block/rbd.c:2499:1: error: control reaches end of non-void function [-Werror=return-type]
> drivers/block/rbd.c: In function 'rbd_obj_handle_write':
> drivers/block/rbd.c:2471:1: error: control reaches end of non-void function [-Werror=return-type]
>
> As the rbd_assert() here shows has no extra information beyond the verbose
> BUG(), we can simply use BUG() directly in its place.  This is reliably
> detected as not returning on any architecture, since it doesn't depend
> on the unlikely() comparison that confused gcc.
>
> Fixes: 3da691bf4366 ("rbd: new request handling code")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/block/rbd.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index 07dc5419bd63..5f7f4d4b78a8 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -1392,7 +1392,7 @@ static bool rbd_img_is_write(struct rbd_img_request *img_req)
>         case OBJ_OP_DISCARD:
>                 return true;
>         default:
> -               rbd_assert(0);
> +               BUG();
>         }
>  }
>
> @@ -2466,7 +2466,7 @@ static bool rbd_obj_handle_write(struct rbd_obj_request *obj_req)
>                 }
>                 return false;
>         default:
> -               rbd_assert(0);
> +               BUG();
>         }
>  }
>
> @@ -2494,7 +2494,7 @@ static bool __rbd_obj_handle_request(struct rbd_obj_request *obj_req)
>                 }
>                 return false;
>         default:
> -               rbd_assert(0);
> +               BUG();
>         }
>  }
>

Applied.

Thanks,

                Ilya