On Mon, May 08, 2023 at 02:06:34PM +0200, Geert Uytterhoeven wrote:
> With gcc-5:
>
> In file included from ./include/trace/define_trace.h:102:0,
> from ./fs/xfs/scrub/trace.h:988,
> from fs/xfs/scrub/trace.c:40:
> ./fs/xfs/./scrub/trace.h: In function ‘trace_raw_output_xchk_fsgate_class’:
> ./fs/xfs/scrub/scrub.h:111:28: error: initializer element is not constant
> #define XREP_ALREADY_FIXED (1 << 31) /* checking our repair work */
> ^
>
> Shifting the (signed) value 1 into the sign bit is undefined behavior.
>
> Fix this for all definitions in the file by shifting "1U" instead of
> "1".
>
> This was exposed by the first user added in commit 466c525d6d35e691
> ("xfs: minimize overhead of drain wakeups by using jump labels").
>
> Fixes: 160b5a784525e8a4 ("xfs: hoist the already_fixed variable to the scrub context")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> fs/xfs/scrub/scrub.h | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
> index b38e93830ddea2b0..e113f2f5c254b085 100644
> --- a/fs/xfs/scrub/scrub.h
> +++ b/fs/xfs/scrub/scrub.h
> @@ -105,10 +105,10 @@ struct xfs_scrub {
> };
>
> /* XCHK state flags grow up from zero, XREP state flags grown down from 2^31 */
> -#define XCHK_TRY_HARDER (1 << 0) /* can't get resources, try again */
> -#define XCHK_FSGATES_DRAIN (1 << 2) /* defer ops draining enabled */
> -#define XCHK_NEED_DRAIN (1 << 3) /* scrub needs to drain defer ops */
> -#define XREP_ALREADY_FIXED (1 << 31) /* checking our repair work */
> +#define XCHK_TRY_HARDER (1U << 0) /* can't get resources, try again */
> +#define XCHK_FSGATES_DRAIN (1U << 2) /* defer ops draining enabled */
> +#define XCHK_NEED_DRAIN (1U << 3) /* scrub needs to drain defer ops */
> +#define XREP_ALREADY_FIXED (1U << 31) /* checking our repair work */
DOH. My mistake. :(
Does gcc have an explicit warning for that? I turned on W=12e on gcc
11.3 and UBSAN and neither complain about this.
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
>
> /*
> * The XCHK_FSGATES* flags reflect functionality in the main filesystem that
> --
> 2.34.1
>
