Re: [PATCH] md: dm-writeback: add __noreturn to BUG-ging function

Christian Borntraeger
2020-11-16T07:30:21Z

On 13.11.20 23:52, Randy Dunlap wrote:
> Building on arch/s390/ flags this as an error, so add the
> __noreturn attribute modifier to prevent the build error.
>
> cc1: some warnings being treated as errors
> ../drivers/md/dm-writecache.c: In function 'persistent_memory_claim':
> ../drivers/md/dm-writecache.c:323:1: error: no return statement in function returning non-void [-Werror=return-type]

ok with me, but I am asking why

the unreachable macro is not good enough. For x86 it obviously is.

form arch/s390/include/asm/bug.h
#define BUG() do { \
__EMIT_BUG(0); \
unreachable(); \
} while (0)

>
> Fixes: 48debafe4f2f ("dm: add writecache target")
> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
> Cc: Mikulas Patocka <mpatocka@redhat.com>
> Cc: Alasdair Kergon <agk@redhat.com>
> Cc: Mike Snitzer <snitzer@redhat.com>
> Cc: dm-devel@redhat.com
> Cc: Heiko Carstens <hca@linux.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: linux-s390@vger.kernel.org
> ---
> drivers/md/dm-writecache.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- linux-next-20201113.orig/drivers/md/dm-writecache.c
> +++ linux-next-20201113/drivers/md/dm-writecache.c
> @@ -317,7 +317,7 @@ err1:
> return r;
> }
> #else
> -static int persistent_memory_claim(struct dm_writecache *wc)
> +static int __noreturn persistent_memory_claim(struct dm_writecache *wc)
> {
> BUG();
> }
>