linux-kernel - Re: [PATCH] zram: fix possible race when checking idle

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Message-ID: <20150811082524.GA562@swordfish>
Date:	Tue, 11 Aug 2015 17:25:24 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:	Minchan Kim <minchan@...nel.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
	paulmck@...ux.vnet.ibm.com, peterz@...radead.org
Subject: Re: [PATCH] zram: fix possible race when checking idle_strm

On (08/11/15 17:25), Joonsoo Kim wrote:
[..]
> > "SLEEP AND WAKE-UP FUNCTIONS
> > ---------------------------
> > 
> > Sleeping and waking on an event flagged in global data ...
> > ...
> > ...
> > ...
> > 
> > A general memory barrier is interpolated automatically by set_current_state()
> > after it has altered the task state:"
> > 
> > So I think your T1-7 assumption is not true.
> > 
> > As well, there are many examples under drivers/ to use the global data
> > as event flag without locking or atomic.
> > 
> 
> Okay. Now, I'm convinced that race is not possible. I will drop this
> patch.

yep, Minchan found it first. thanks guys.

	-ss
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