On Fri, Feb 19, 2010 at 09:29:05AM +0100, Clemens Ladisch wrote:
> > This doesn't change anything, but I think it makes the code clearer.
> > It silences a smatch warning:
> > sound/pci/oxygen/oxygen_mixer.c +91 dac_mute_put(7) warn: add some parenthesis here?
>
> That message doesn't say why some parentheses should be added.
> And it's a question; how do I give it the answer "no"? :-)
>
> > - changed = !value->value.integer.value[0] != chip->dac_mute;
> > + changed = (!value->value.integer.value[0]) != chip->dac_mute;
>
> This doesn't look any clearer to me; I don't think that the unary
> negation operator could be thought to have lower precedence than "!=".
>
Well, it's hard to argue that it's more ambiguous. :P
> Why does smatch warn about this combination? Do such errors actually
> happen?
>
Yep. I have made some myself when writing smatch.
For example here are some related bugs in the current kernel.
drivers/staging/rtl8192u/ieee80211/ieee80211_wx.c
721 if (!ext->ext_flags & IW_ENCODE_EXT_GROUP_KEY &&
722 ext->alg != IW_ENCODE_ALG_WEP)
723 if (idx != 0 || ieee->iw_mode != IW_MODE_INFRA)
724 return -EINVAL;
if (!j->dsp.low != 0x20) {
drivers/telephony/ixj.c
6834 if (!j->dsp.low != 0x20) {
Mostly the real bugs have been fixed now. Roel Kluin fixed quite a
few of these before and I've fixed a couple.
regards,
dan carpenter
>
> Regards,
> Clemens
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