From: Al Viro <viro@ZenIV.linux.org.uk>
To: Vasyl Gomonovych <gomonovych@gmail.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] epoll: fix dereferenced before check pt
Date: Fri, 22 Dec 2017 00:02:07 +0000 [thread overview]
Message-ID: <20171222000207.GY21978@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1513871657-11239-1-git-send-email-gomonovych@gmail.com>
On Thu, Dec 21, 2017 at 04:54:17PM +0100, Vasyl Gomonovych wrote:
> This patch fixes the warning reported by smatch:
>
> fs/eventpoll.c:889 ep_item_poll() warn: variable dereferenced before check 'pt'
... and of course, that is all the analysis one might want - the tool has
spoken. Except that the only thing proven is that the tool is either misused
or just plain crappy.
Callers of ep_item_poll() are easily found - it's static, so they all are in
the same file. All four of them -
if (ep_item_poll(epi, &pt, depth)) {
revents = ep_item_poll(epi, &epq.pt, 1);
if (ep_item_poll(epi, &pt, 1)) {
revents = ep_item_poll(epi, &pt, 1);
Figuring out why an address of a local variable or of a field thereof can never
be NULL is left as an exercise for an introductory course on C.
"Fixing warnings" is bloody wrong - warning (from any tool) is a heuristic
pointing to a place that might be worth looking into. In cases when you've
found a real problem with help from some tool, sure, go ahead and credit that
tool in the commit message. Along with the description of the problem
you've found.
prev parent reply other threads:[~2017-12-22 0:02 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-21 15:54 [PATCH] epoll: fix dereferenced before check pt Vasyl Gomonovych
2017-12-22 0:02 ` Al Viro [this message]
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