Re: [alsa-devel] [patch] oxygen: clean up. make precedence explicit
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 "!=".
Why does smatch warn about this combination? Do such errors actually happen?
Regards, Clemens
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 -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
participants (2)
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Clemens Ladisch -
Dan Carpenter