From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758822Ab2DYCtU (ORCPT ); Tue, 24 Apr 2012 22:49:20 -0400 Received: from cantor2.suse.de ([195.135.220.15]:48497 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758003Ab2DYCtT (ORCPT ); Tue, 24 Apr 2012 22:49:19 -0400 Date: Wed, 25 Apr 2012 12:49:14 +1000 From: NeilBrown To: Evgeniy Polyakov Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman Subject: [PATCH] w1: Introduce a slave mutex for serializing IO. Message-ID: <20120425124914.3187a794@notabene.brown> X-Mailer: Claws Mail 3.7.10 (GTK+ 2.24.7; x86_64-suse-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/5O4YJ/UCVeL3_FMrSku0zQp"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/5O4YJ/UCVeL3_FMrSku0zQp Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable w1 devices need a mutex to serial IO. Most use master->mutex. However that is used for other purposes and they can conflict. In particular master->mutex is held while w1_attach_slave_device is called. For bq27000, this registers a 'powersupply' device which tries to read the current status. The attempt to read will cause a deadlock on master->mutex. So create a new per-slave mutex and use that for serializing IO for bq27000. Signed-off-by: NeilBrown --- drivers/w1/slaves/w1_bq27000.c | 4 ++-- drivers/w1/w1.c | 1 + drivers/w1/w1.h | 1 + 3 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/w1/slaves/w1_bq27000.c b/drivers/w1/slaves/w1_bq27000.c index 52ad812..8755478 100644 --- a/drivers/w1/slaves/w1_bq27000.c +++ b/drivers/w1/slaves/w1_bq27000.c @@ -31,10 +31,10 @@ static int w1_bq27000_read(struct device *dev, unsigned= int reg) u8 val; struct w1_slave *sl =3D container_of(dev->parent, struct w1_slave, dev); =20 - mutex_lock(&sl->master->mutex); + mutex_lock(&sl->mutex); w1_write_8(sl->master, HDQ_CMD_READ | reg); val =3D w1_read_8(sl->master); - mutex_unlock(&sl->master->mutex); + mutex_unlock(&sl->mutex); =20 return val; } diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c index 9761950..2173f83 100644 --- a/drivers/w1/w1.c +++ b/drivers/w1/w1.c @@ -688,6 +688,7 @@ static int w1_attach_slave_device(struct w1_master *dev= , struct w1_reg_num *rn) memcpy(&sl->reg_num, rn, sizeof(sl->reg_num)); atomic_set(&sl->refcnt, 0); init_completion(&sl->released); + mutex_init(&sl->mutex); =20 spin_lock(&w1_flock); f =3D w1_family_registered(rn->family); diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h index 4d012ca..8c8be38 100644 --- a/drivers/w1/w1.h +++ b/drivers/w1/w1.h @@ -75,6 +75,7 @@ struct w1_slave void *family_data; struct device dev; struct completion released; + struct mutex mutex; }; =20 typedef void (*w1_slave_found_callback)(struct w1_master *, u64); --=20 1.7.10 --Sig_/5O4YJ/UCVeL3_FMrSku0zQp Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBT5dmKjnsnt1WYoG5AQJ1OxAAmEEsVNPtJBqD8kpoTXFAlO5a9XFfLaQZ +hckArT/dgSr+BlfqHnR175GLP3hBrcFo2s6l3CfKcUVyj15PGqrXRN6Jm/i78M6 TCclN8rKQKhMt4hLLOaSh0MifD/E6ep87mP5pwiu2WgulqzhxUYrF2kA+ly/uqrI B/NN2QhLEA3PEqB6bB1ohrPXpuedKZPuL0Wxa63dJkpOAwD8JRxLhcTaC+Zzic3J ifaVz3amNL3bBbBCqXOeztpIbHmAA4KKlxZ6K/KUp7NDdk32j8Q1jC3bisRl4/b4 IM54TLaymFo6hT7z0u93y6P8w8BXEiLhxUlLFtY43mv+fhK1NUi2BOlxhlkJAwwP auX7z9+OztkcMCubjEt3kOW9GPPU5wR8g5rirUR25BRDWY9fCEU1eNXoAhXRd5cF GQYCr/jH9XzW4rEX4jknLy7ULuljltV4xv0qTrxTWknHSXGpMReEoqBUT0x8Lv+7 06tItfMz2hGZhFSn06dIDbCzujoEyuTAKdU/E8yP9546/W+ZzVkAK6WYTZx0Ctau vqayGmI6yq9B3A+ytmXsfd7tFw6gGInuwa4lS8/ePJrKRpfBiTkEDvLfwATSzJ9+ HAKWgOOOTO9iXAocP4chMjCU26mIsI0nkRLBBiKujRHaI5Xuff94Esfo2/3JaZHr xWNdALnYim4= =M1hy -----END PGP SIGNATURE----- --Sig_/5O4YJ/UCVeL3_FMrSku0zQp--