On Fri, Jul 14, 2017 at 12:08 PM, Joe Perches <joe@xxxxxxxxxxx> wrote:
> On Fri, 2017-07-14 at 11:25 +0200, Arnd Bergmann wrote:
>> We test whether a bit is set in a mask here, which is correct
>> but gcc warns about it as it thinks it might be confusing:
>>
>> drivers/isdn/isdnloop/isdnloop.c:412:37: error: ?: using integer constants in boolean context, the expression will always evaluate to 'true' [-Werror=int-in-bool-context]
>>
>> This replaces the negation of an integer with an equivalent
>> comparison to zero, which gets rid of the warning.
> []
>> diff --git a/drivers/isdn/isdnloop/isdnloop.c b/drivers/isdn/isdnloop/isdnloop.c
> []
>> @@ -409,7 +409,7 @@ isdnloop_sendbuf(int channel, struct sk_buff *skb, isdnloop_card *card)
>> return -EINVAL;
>> }
>> if (len) {
>> - if (!(card->flags & (channel) ? ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE))
>> + if ((card->flags & (channel) ? ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE) == 0)
>> return 0;
>> if (card->sndcount[channel] > ISDNLOOP_MAX_SQUEUE)
>> return 0;
>
> The if as written can not be zero.
>
> drivers/isdn/isdnloop/isdnloop.h:#define ISDNLOOP_FLAGS_B1ACTIVE 1 /* B-Channel-1 is open */
> drivers/isdn/isdnloop/isdnloop.h:#define ISDNLOOP_FLAGS_B2ACTIVE 2 /* B-Channel-2 is open */
>
> Perhaps this is a logic defect and should be:
>
> if (!(card->flags & ((channel) ? ISDNLOOP_FLAGS_B2ACTIVE : ISDNLOOP_FLAGS_B1ACTIVE)))
Yes, good catch. I had thought about it for a bit whether that would be
the answer, but come to the wrong conclusion on my own.
Note that the version you suggested will still have the warning, so I think
it needs to be
if (card->flags &
((channel) ? ISDNLOOP_FLAGS_B2ACTIVE :
ISDNLOOP_FLAGS_B1ACTIVE)
== 0)
or something like that, probably having a temporary flag variable would be best:
int flag = channel ? ISDNLOOP_FLAGS_B2ACTIVE :
ISDNLOOP_FLAGS_B1ACTIVE;
if ((card->flags & flag) == 0)
return 0;
Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
