2018-04-04 12:56:47

by Arnd Bergmann

Subject: [PATCH] [v2] rbd: avoid Wreturn-type warnings

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 <[email protected]>
---
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();
}
}

--
2.9.0

2018-04-04 13:11:57

by Ilya Dryomov

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

On Wed, Apr 4, 2018 at 2:53 PM, Arnd Bergmann <[email protected]> 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 <[email protected]>
> ---
> 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