Re: [PATCH 6/9] drivers/net/wireless/iwlwifi/iwl-4965.c: Correctuse of ! and &

[Ingo Molnar]

* Julia Lawall <julia@xxxxxxx> wrote:

> From: Julia Lawall <julia@xxxxxxx>
> 
> In commit e6bafba5b4765a5a252f1b8d31cbf6d2459da337, a bug was fixed 
> that involved converting !x & y to !(x & y).  The code below shows the 
> same pattern, and thus should perhaps be fixed in the same way.

>  	if (sta_ht_inf) {
>  		if ((!sta_ht_inf->ht_supported) ||
> -		   (!sta_ht_inf->cap & IEEE80211_HT_CAP_SUP_WIDTH))
> +		   (!(sta_ht_inf->cap & IEEE80211_HT_CAP_SUP_WIDTH)))
>  			return 0;

i'm wondering, could Sparse be extended to check for such patterns? 

People are regularly running "make C=1" and are sending fixes to make 
entire subsystems sparse-warning-free, so Sparse is a nice mechanism 
that works and it keeps code clean in the long run.

I dont think the "!X & Y" pattern is ever used legitimately [and even if 
it were used legitimately, it's easy to avoid the sparse false positive 
- while in the buggy case we have a clear bug].

	Ingo
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