Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Kirill Smelkov <kirr@nexedi.com>
Subject: Re: [Cocci] [PATCH 1/2] coccinelle: api/stream_open: treat all wait_.*() calls as blocking
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     <cocci@systeme.lip6.fr>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Logan Gunthorpe <logang@deltatee.com>
Message-Id: <20190707182002.GB25031@deco.navytux.spb.ru>
References: <20190623072838.31234-1-kirr@nexedi.com> <CAK7LNAT2tt+pCX54=L9qN9pzZ+rCOQ5-9p-o1jMLa3GD9jhG8A@mail.gmail.com>
In-Reply-To: <CAK7LNAT2tt+pCX54=L9qN9pzZ+rCOQ5-9p-o1jMLa3GD9jhG8A@mail.gmail.com>
Date:   Sun, 07 Jul 2019 18:20:06 +0000
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sat, Jul 06, 2019 at 10:17:18PM +0900, Masahiro Yamada wrote:
> On Sun, Jun 23, 2019 at 4:29 PM Kirill Smelkov <kirr@nexedi.com> wrote:
> >
> > Previously steam_open.cocci was treating only wait_event_.* - e.g.
> > wait_event_interruptible - as a blocking operation. However e.g.
> > wait_for_completion_interruptible is also blocking, and so from this
> > point of view it would be more logical to treat all wait_.* as a
> > blocking point.
> >
> > The logic of this change actually came up for real when
> > drivers/pci/switch/switchtec.c changed from using
> > wait_event_interruptible to wait_for_completion_interruptible:
> >
> >         https://lore.kernel.org/linux-pci/20190413170056.GA11293@deco.navytux.spb.ru/
> >         https://lore.kernel.org/linux-pci/20190415145456.GA15280@deco.navytux.spb.ru/
> >         https://lore.kernel.org/linux-pci/20190415154102.GB17661@deco.navytux.spb.ru/
> >
> > For a driver that uses nonseekable_open with read/write having stream
> > semantic and read also calling e.g. wait_for_completion_interruptible,
> > running stream_open.cocci before this patch would produce:
> >
> >         WARNING: <driver>_fops: .read() and .write() have stream semantic; safe to change nonseekable_open -> stream_open.
> >
> > while after this patch it will report:
> >
> >         ERROR: <driver>_fops: .read() can deadlock .write(); change nonseekable_open -> stream_open to fix.
> >
> > Cc: Julia Lawall <Julia.Lawall@lip6.fr>
> > Cc: Logan Gunthorpe <logang@deltatee.com>
> > Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> > Cc: Bjorn Helgaas <helgaas@kernel.org>
> > Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
> > ---
> 
> Applied to linux-kbuild. Thanks.

Thanks.


> >  scripts/coccinelle/api/stream_open.cocci | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/scripts/coccinelle/api/stream_open.cocci b/scripts/coccinelle/api/stream_open.cocci
> > index 350145da7669..12ce18fa6b74 100644
> > --- a/scripts/coccinelle/api/stream_open.cocci
> > +++ b/scripts/coccinelle/api/stream_open.cocci
> > @@ -35,11 +35,11 @@ type loff_t;
> >  // a function that blocks
> >  @ blocks @
> >  identifier block_f;
> > -identifier wait_event =~ "^wait_event_.*";
> > +identifier wait =~ "^wait_.*";
> >  @@
> >    block_f(...) {
> >      ... when exists
> > -    wait_event(...)
> > +    wait(...)
> >      ... when exists
> >    }
> >
> > @@ -49,12 +49,12 @@ identifier wait_event =~ "^wait_event_.*";
> >  // XXX currently reader_blocks supports only direct and 1-level indirect cases.
> >  @ reader_blocks_direct @
> >  identifier stream_reader.readstream;
> > -identifier wait_event =~ "^wait_event_.*";
> > +identifier wait =~ "^wait_.*";
> >  @@
> >    readstream(...)
> >    {
> >      ... when exists
> > -    wait_event(...)
> > +    wait(...)
> >      ... when exists
> >    }
> >
> > --
> > 2.20.1
> > _______________________________________________
> > Cocci mailing list
> > Cocci@systeme.lip6.fr
> > https://systeme.lip6.fr/mailman/listinfo/cocci
> 
> 
> 
> -- 
> Best Regards
> Masahiro Yamada