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From: Julia Lawall <julia.lawall@lip6.fr>
To: Sasha Levin <sashal@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>,
	wen.yang99@zte.com.cn, Markus.Elfring@web.de,
	cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org,
	Gilles Muller <Gilles.Muller@lip6.fr>,
	yamada.masahiro@socionext.com, michal.lkml@markovi.net,
	nicolas.palix@imag.fr
Subject: Re: Coccinelle: semantic patch for missing of_node_put
Date: Mon, 20 May 2019 21:53:40 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1905202151140.2561@hadrien> (raw)
In-Reply-To: <20190520172041.GH11972@sasha-vm>



On Mon, 20 May 2019, Sasha Levin wrote:

> On Mon, May 20, 2019 at 11:52:37AM +0200, Julia Lawall wrote:
> >
> >
> > On Mon, 20 May 2019, Pavel Machek wrote:
> >
> > > Hi!
> > >
> > > > A semantic patch has no access to comments.  The only thing I can see to
> > > > do is to use python to interact with some external tools.  For example,
> > > > you could write some code to collect the comments in a file and the
> > > lines
> > > > on which they occur, and then get the comment that most closely precedes
> > > > the start of the function.
> > >
> > > How dangerous is missing of_node_put? AFAICT it will only result into
> > > very small, one-time memory leak, right?
> > >
> > > Could we make sure these patches are _not_ going to stable? Leaking
> > > few bytes once per boot is not really a serious bug.
> >
> > Sasha,
> >
> > Probably patches that add only of_node_put should not be auto selected for
> > stable.
>
> I can filter them out, but those are fixes, right? Why are we concerned
> about them making it into -stable?

One of them may have introduced a crash.  If there is a bad reference
count manipulation elsewhere, then fixing one could cause a later
incorrect one to make a double free.

On the other hand, I don't know if the one that seemed to cause a crash
really caused a crash.  It was detected by syzkaller, and it is also
possible that git bisect ended up at the wrong place.

In any case, forgetting an of_node_put will normally just waste a little
memory, so probably stable kernels don't care.

julia

  reply	other threads:[~2019-05-20 19:53 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <201905171432571474636@zte.com.cn>
2019-05-17  7:14 ` Coccinelle: semantic patch for missing of_node_put Julia Lawall
2019-05-17  8:22   ` Markus Elfring
2019-05-20  9:33   ` Pavel Machek
2019-05-20  9:51     ` Julia Lawall
2019-05-20  9:52     ` Julia Lawall
2019-05-20 17:20       ` Sasha Levin
2019-05-20 19:53         ` Julia Lawall [this message]
2019-05-20 20:11           ` Markus Elfring
2019-05-17  8:10 ` Markus Elfring
2019-05-18 14:43 ` Markus Elfring
2019-06-04  5:08 ` Markus Elfring
2019-06-05 18:23   ` Coccinelle: Searching for “when done” in function comments Markus Elfring
     [not found] <201906041655048641633@zte.com.cn>
2019-06-04  9:08 ` Coccinelle: semantic patch for missing of_node_put Markus Elfring
     [not found] <201906041350002807147@zte.com.cn>
2019-06-04  6:36 ` Markus Elfring
2019-06-04 11:28 ` Markus Elfring
     [not found] <201905090947015772925@zte.com.cn>
2019-05-09  8:10 ` Markus Elfring

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