From: Ingo Molnar <mingo@elte.hu>
To: Julia Lawall <julia@diku.dk>
Cc: yi.zhu@intel.com, linux-wireless@vger.kernel.org,
ipw3945-devel@lists.sourceforge.net,
linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
Harvey Harrison <harvey.harrison@gmail.com>,
Alexander Viro <viro@ftp.linux.org.uk>,
linux-sparse@vger.kernel.org,
Josh Triplett <josh@freedesktop.org>
Subject: Re: [PATCH 6/9] drivers/net/wireless/iwlwifi/iwl-4965.c: Correct use of ! and &
Date: Wed, 5 Mar 2008 07:38:42 +0100 [thread overview]
Message-ID: <20080305063842.GA24495@elte.hu> (raw)
In-Reply-To: <Pine.LNX.4.64.0802262143570.18200@ask.diku.dk>
* Julia Lawall <julia@diku.dk> wrote:
> From: Julia Lawall <julia@diku.dk>
>
> 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
next prev parent reply other threads:[~2008-03-05 6:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-26 20:44 [PATCH 6/9] drivers/net/wireless/iwlwifi/iwl-4965.c: Correct use of ! and & Julia Lawall
2008-02-26 22:47 ` Tomas Winkler
2008-02-27 0:59 ` John W. Linville
2008-03-05 6:38 ` Ingo Molnar [this message]
2008-03-05 6:49 ` Christopher Li
2008-03-05 7:02 ` Ingo Molnar
2008-03-05 7:09 ` Harvey Harrison
2008-03-05 8:19 ` Ingo Molnar
2008-03-05 12:13 ` Derek M Jones
2008-03-05 8:55 ` Julia Lawall
2008-03-05 12:20 ` Ingo Molnar
2008-03-05 12:30 ` Bart Van Assche
2008-03-05 12:36 ` Ingo Molnar
2008-03-05 12:35 ` Julia Lawall
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