2013/7/16 Paul Bolle <pebolle@xxxxxxxxxx>:
> Building scsi_debug.o triggers a GCC warning:
> drivers/scsi/scsi_debug.c: In function ‘dif_verify’:
> drivers/scsi/scsi_debug.c:1755:3: warning: ‘csum’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>
> This is a false positive. But if we transform the switch statement in
> dif_compute_csum() to a straightforward if/else statement we supply GCC
> with enough information to determine that csum will not be used
> uninitialized.
>
> Signed-off-by: Paul Bolle <pebolle@xxxxxxxxxx>
> ---
> 0) v2 because I started to worry whether v1 would change an interface
> (ie, the way the "guard" module parameter behaves). This patch is much
> simpler, and doesn't change any behavior.
>
> 1) Still only compile tested.
This one looks good to me. It would be much better if this commit
log had a reference to the commit that introduced this warning as
you described after '---' in v1 patch.
> drivers/scsi/scsi_debug.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index cb4fefa..7565ec5 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -1735,14 +1735,11 @@ static u16 dif_compute_csum(const void *buf, int len)
> {
> u16 csum;
>
> - switch (scsi_debug_guard) {
> - case 1:
> + if (scsi_debug_guard == 1)
> csum = ip_compute_csum(buf, len);
> - break;
> - case 0:
> + else
> csum = cpu_to_be16(crc_t10dif(buf, len));
> - break;
> - }
> +
> return csum;
> }
>
> --
> 1.8.1.4
>
> --
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