Re: [PATCH] scsi: scsi_debug: negate wrapped memcmp() result

[John Garry]

On 03/08/2026 10:53, raoxu wrote:
> From: Xu Rao <raoxu@xxxxxxxxxxxxx>
>
> comp_write_worker() returns true when the compared data matches.
> memcmp() returns zero for equal data and non-zero for different data, so
> its result must be negated before it is stored in a bool.
>
> The first segment already uses !memcmp(), but the wrapped segment uses
> memcmp() directly, reversing the match result. Use !memcmp() there as
> well.
>
> Fixes: 38d5c8336e60 ("scsi_debug: add Report supported opcodes+tmfs; Compare and write")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Xu Rao <raoxu@xxxxxxxxxxxxx>

Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>

> ---
>   drivers/scsi/scsi_debug.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index 9d1c9c41d0f9..a5911482fc44 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -4310,8 +4310,8 @@ static bool comp_write_worker(struct sdeb_store_info *sip, u64 lba, u32 num,
>   	if (!res)
>   		return res;
>   	if (rest)
> -		res = memcmp(fsp, arr + ((num - rest) * lb_size),
> -			     rest * lb_size);
> +		res = !memcmp(fsp, arr + ((num - rest) * lb_size),
> +			      rest * lb_size);
>   	if (!res)
>   		return res;
>   	if (compare_only)
> --
> 2.50.1