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From:   Gal Ben Haim <gbenhaim@augury.com>
Date:   Mon, 19 Nov 2018 11:47:02 +0200
Message-ID: <CAHotPr-pPNwawo+uU=4QbSNSdNbFcoBbnr-LY_fMiwMQW+1aew@mail.gmail.com>
Subject: Re: [PATCH BlueZ] core: Catch SIGPIPE
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc:     linux-bluetooth@vger.kernel.org
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Sender: linux-bluetooth-owner@vger.kernel.org
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are you suggesting to have a single socketpair for both notify_io and
write_io or 2x socketpair instead of 2x pipe2 ?

On Mon, Nov 19, 2018 at 11:22 AM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Gal,
>
> On Sat, Nov 17, 2018 at 10:48 PM Gal Ben Haim <gbenhaim@augury.com> wrote:
> >
> > i don't think it works at all... bluetoothd is still exiting with SIGPIPE.
> > i'm a bit lost with fixing this, I tried few methods that were
> > suggested here and the only one that actually worked is to ignore the
> > signal.
> >
> > please advise how do you want to proceed with this..
>
> We might be better of switching to socketpair instead of pipe2 then,
> not only we can fix this problem using MSG_NOSIGNAL but also use
> sendmsg and setting auxiliary data which can be used to set things
> like the offset.
>
> > On Sat, Nov 17, 2018 at 10:41 PM Gal Ben Haim <gbenhaim@augury.com> wrote:
> > >
> > > actually it does not log the broken pipe message, is it because errno
> > > isn't set before the signal handler is done?
> > > what do you think?
> > > On Sat, Nov 17, 2018 at 8:00 AM Gal Ben-Haim <gbenhaim@augury.com> wrote:
> > > >
> > > > bluetoothd receives a SIGPIPE and terminates if writing to a pipe that
> > > > was acquired by AcquireNotify and there are no readers. it can be
> > > > reproduced by terminating the reader process without closing the reader
> > > > end of the pipe.
> > > >
> > > > Catching SIGPIPE will cause the write call to return an EPIPE error
> > > > which will be logged as "io_send: Broken pipe".
> > > > ---
> > > >  src/main.c | 3 +++
> > > >  1 file changed, 3 insertions(+)
> > > >
> > > > diff --git a/src/main.c b/src/main.c
> > > > index 4716f5388..54cdb8d3f 100644
> > > > --- a/src/main.c
> > > > +++ b/src/main.c
> > > > @@ -533,6 +533,8 @@ static gboolean signal_handler(GIOChannel *channel, GIOCondition cond,
> > > >         case SIGUSR2:
> > > >                 __btd_toggle_debug();
> > > >                 break;
> > > > +       case SIGPIPE:
> > > > +               break;
> > > >         }
> > > >
> > > >         return TRUE;
> > > > @@ -549,6 +551,7 @@ static guint setup_signalfd(void)
> > > >         sigaddset(&mask, SIGINT);
> > > >         sigaddset(&mask, SIGTERM);
> > > >         sigaddset(&mask, SIGUSR2);
> > > > +       sigaddset(&mask, SIGPIPE);
> > > >
> > > >         if (sigprocmask(SIG_BLOCK, &mask, NULL) < 0) {
> > > >                 perror("Failed to set signal mask");
> > > > --
> > > > 2.19.1
> > > >
>
>
>
> --
> Luiz Augusto von Dentz