From: Andrew Morton <akpm@linux-foundation•org>
To: Peter Zijlstra <peterz@infradead•org>
Cc: Gregory CLEMENT <gregory.clement@free-electrons•com>,
"linux-kernel@vger•kernel.org" <linux-kernel@vger•kernel.org>,
linux-next@vger•kernel.org,
Johannes Berg <johannes.berg@intel•com>,
Steven Rostedt <rostedt@goodmis•org>
Subject: Re: Regression with wait_event_timeout in next-20140226
Date: Wed, 26 Feb 2014 14:25:34 -0800 [thread overview]
Message-ID: <20140226142534.3b8c6eb1652d000206948ae0@linux-foundation.org> (raw)
In-Reply-To: <20140226165043.GA22802@laptop.programming.kicks-ass.net>
On Wed, 26 Feb 2014 17:50:43 +0100 Peter Zijlstra <peterz@infradead•org> wrote:
> On Wed, Feb 26, 2014 at 05:35:19PM +0100, Gregory CLEMENT wrote:
> > Hi,
> >
> > while testing next-20140226 I got an issue with the function
> > wait_event_timeout. When this function timed out instead of returning
> > 0, it returned the value of the timeout passed in parameter. I found
> > that reverting "sched/wait: Suppress Sparse 'variable shadowing'
> > warning" fixed this regression.
> >
> > I got this issue in the driver drivers/i2c/busses/i2c-mv64xxx.c.
>
> Ah indeed. We actually rely on the shadowing for ___wait_cond_timeout().
>
> We further used the __ret variable in __wait_event_timeout()'s cmd
> argument: __ret = schedule_timeout(__ret). That now explicitly uses the
> wrong __ret.
>
> Yeah, we need to pull that patch.
Is there anything we can do to make all this clearer? Simply using a
distinctive variable name ("__wait_var__"?) in place of __ret (and
documenting it) would help a lot.
Some __ret's are long and some are int. Maybe that's a glitch, maybe
it's because some __ret's are used for inter-macro communications and
some are not, which just makes things worse.
I started to do a patch, got all confused and gave up. We've made
quite a tangly mess in there, alas.
next prev parent reply other threads:[~2014-02-26 22:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-26 16:35 Regression with wait_event_timeout in next-20140226 Gregory CLEMENT
2014-02-26 16:50 ` Peter Zijlstra
2014-02-26 22:25 ` Andrew Morton [this message]
2014-02-26 22:35 ` Peter Zijlstra
2014-04-09 11:16 ` Peter Zijlstra
2014-04-09 19:05 ` Andrew Morton
2014-02-27 3:12 ` Stephen Rothwell
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