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From: Anisse Astier <anisse@astier.eu>
To: Phil Elwell <phil@raspberrypi.org>
Cc: Stefan Wahren <stefan.wahren@i2se.com>,
	devel@driverdev.osuosl.org, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org, Eric Anholt <eric@anholt.net>,
	linux-rpi-kernel@lists.infradead.org,
	Dominic Braun <inf.braun@fau.de>,
	Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] staging: vchiq: Fix local event signalling
Date: Sun, 20 Jan 2019 23:21:40 +0100
Message-ID: <20190120222140.GA6626@jaya.lan> (raw)
In-Reply-To: <1547206493-105303-1-git-send-email-phil@raspberrypi.org>

Hi Phil,

On Fri, Jan 11, 2019 at 11:34:53AM +0000, Phil Elwell wrote:
> Prior to the recent event reworking (see Fixes), thread synchronisation
> was implemented using completions, the worker thread being woken with
> a call to complete(). The replacement uses waitqueues, which are more
> like condition variables in that the waiting thread is only woken if
> the condition is true.
> 
> When the VPU signals the ARM, it first sets the event's fired flag to
> indicate which event is being signalled, but the places in the
> ARM-side code where the worker thread is being woken -
> remote_event_signal_local via request_poll - did not do so as it
> wasn't previously necessary, and since the armed flag was being
> cleared this lead to a deadlock.

This fixes an issue I've had on linux 5.0-pre to 5.0-rc2+: the
bcm2835-audio driver would block on close, and then nothing would work
until the process was killed. Sample log:

bcm2835_audio bcm2835_audio: failed to close VCHI service connection (status=1)

> 
> Fixes: 852b2876a8a8 ("staging: vchiq: rework remove_event handling")
> Signed-off-by: Phil Elwell <phil@raspberrypi.org>

Tested-by: Anisse Astier <anisse@astier.eu>


Regards,

Anisse

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Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-11 11:34 Phil Elwell
2019-01-12  0:14 ` Stefan Wahren
2019-01-20 22:21 ` Anisse Astier [this message]

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