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Subject: Re: [PATCH BlueZ] core: Ignore SIGPIPE
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20181116191452.17377-1-gbenhaim@augury.com>
Date:   Fri, 16 Nov 2018 21:01:37 +0100
Cc:     linux-bluetooth@vger.kernel.org
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Message-Id: <5F365876-5DA6-4916-B810-E2DF1ABD3772@holtmann.org>
References: <20181116191452.17377-1-gbenhaim@augury.com>
To:     Gal Ben-Haim <gbenhaim@augury.com>
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Hi Gal,

> 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.
> 
> Ignoring the SIGPIPE will cause the write operation to return an
> error which will be logged as "io_send: Broken pipe".
> ---
> src/main.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/src/main.c b/src/main.c
> index 4716f5388..c62886593 100644
> --- a/src/main.c
> +++ b/src/main.c
> @@ -691,7 +691,7 @@ int main(int argc, char *argv[])
> 	uint16_t sdp_mtu = 0;
> 	uint32_t sdp_flags = 0;
> 	int gdbus_flags = 0;
> -	guint signal, watchdog;
> +	guint signal_source, watchdog;
> 	const char *watchdog_usec;
> 
> 	init_defaults();
> @@ -721,7 +721,11 @@ int main(int argc, char *argv[])
> 
> 	event_loop = g_main_loop_new(NULL, FALSE);
> 
> -	signal = setup_signalfd();
> +	signal_source = setup_signalfd();
> +
> +	/* Ignore SIGPIPE, a broken pipe error will be returned from write 
> +	 * attempts to a pipe with no readers */
> +	signal(SIGPIPE, SIG_IGN);

if we decide not to use MSG_NOSIGNAL, then everything has to go via signalfd and not just by hacking in signal(SIG_IGN).

Regards

Marcel