From patchwork Wed Mar 30 20:03:27 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Boris BREZILLON X-Patchwork-Id: 8703341 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id C4766C0553 for ; Wed, 30 Mar 2016 20:10:18 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A80CF20361 for ; Wed, 30 Mar 2016 20:10:17 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5E72820389 for ; Wed, 30 Mar 2016 20:10:16 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1alMPw-00009I-C6; Wed, 30 Mar 2016 20:08:40 +0000 Received: from down.free-electrons.com ([37.187.137.238] helo=mail.free-electrons.com) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1alMMH-0004Sj-QD; Wed, 30 Mar 2016 20:04:59 +0000 Received: by mail.free-electrons.com (Postfix, from userid 110) id A8B5A1827; Wed, 30 Mar 2016 22:04:34 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from localhost.localdomain (LFbn-1-2159-240.w90-76.abo.wanadoo.fr [90.76.216.240]) by mail.free-electrons.com (Postfix) with ESMTPSA id D4A71181A; Wed, 30 Mar 2016 22:04:22 +0200 (CEST) From: Boris Brezillon To: Thierry Reding , linux-pwm@vger.kernel.org Subject: [PATCH v5 04/46] pwm: get rid of pwm->lock Date: Wed, 30 Mar 2016 22:03:27 +0200 Message-Id: <1459368249-13241-5-git-send-email-boris.brezillon@free-electrons.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1459368249-13241-1-git-send-email-boris.brezillon@free-electrons.com> References: <1459368249-13241-1-git-send-email-boris.brezillon@free-electrons.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160330_130454_280410_57C73552 X-CRM114-Status: GOOD ( 18.16 ) X-Spam-Score: -2.9 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Milo Kim , Kamil Debski , Heiko Stuebner , linux-doc@vger.kernel.org, David Airlie , Mike Turquette , linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com, Alexandre Belloni , Daniel Vetter , Lee Jones , linux-clk@vger.kernel.org, linux-leds@vger.kernel.org, Boris Brezillon , Krzysztof Kozlowski , linux-samsung-soc@vger.kernel.org, Alexander Shiyan , Jonathan Corbet , Robert Jarzmik , lm-sensors@lm-sensors.org, linux-rockchip@lists.infradead.org, Chen-Yu Tsai , Tomi Valkeinen , linux-input@vger.kernel.org, Jean-Christophe Plagniol-Villard , intel-gfx@lists.freedesktop.org, Guenter Roeck , Jean Delvare , Joachim Eastwood , Bryan Wu , Jani Nikula , Mark Brown , Jacek Anaszewski , linux-arm-kernel@lists.infradead.org, Thomas Petazzoni , Ryan Mallon , Jingoo Han , Dmitry Torokhov , Stephen Boyd , Liam Girdwood , Hartley Sweeten , Richard Purdie , Kukjin Kim , Daniel Vetter , Maxime Ripard MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP PWM devices are not protected against concurrent accesses. The lock in pwm_device might let PWM users think it is, but it's actually only protecting the enabled state. Removing this lock should be fine as long as all PWM users are aware that accesses to the PWM device have to be serialized, which seems to be the case for all of them except the sysfs interface. Patch the sysfs code by adding a lock to the pwm_export struct and making sure it's taken for all accesses to the exported PWM device. Signed-off-by: Boris Brezillon --- drivers/pwm/core.c | 19 ++++-------------- drivers/pwm/sysfs.c | 57 ++++++++++++++++++++++++++++++++++++++++++----------- include/linux/pwm.h | 2 -- 3 files changed, 50 insertions(+), 28 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 7831bc6..7c330ff 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -269,7 +269,6 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip, pwm->pwm = chip->base + i; pwm->hwpwm = i; pwm->polarity = polarity; - mutex_init(&pwm->lock); radix_tree_insert(&pwm_tree, pwm->pwm, pwm); } @@ -474,22 +473,16 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity) if (!pwm->chip->ops->set_polarity) return -ENOSYS; - mutex_lock(&pwm->lock); - - if (pwm_is_enabled(pwm)) { - err = -EBUSY; - goto unlock; - } + if (pwm_is_enabled(pwm)) + return -EBUSY; err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity); if (err) - goto unlock; + return err; pwm->polarity = polarity; -unlock: - mutex_unlock(&pwm->lock); - return err; + return 0; } EXPORT_SYMBOL_GPL(pwm_set_polarity); @@ -506,16 +499,12 @@ int pwm_enable(struct pwm_device *pwm) if (!pwm) return -EINVAL; - mutex_lock(&pwm->lock); - if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) { err = pwm->chip->ops->enable(pwm->chip, pwm); if (err) clear_bit(PWMF_ENABLED, &pwm->flags); } - mutex_unlock(&pwm->lock); - return err; } EXPORT_SYMBOL_GPL(pwm_enable); diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c index 9c90886..ab28c89 100644 --- a/drivers/pwm/sysfs.c +++ b/drivers/pwm/sysfs.c @@ -26,6 +26,7 @@ struct pwm_export { struct device child; struct pwm_device *pwm; + struct mutex lock; }; static struct pwm_export *child_to_pwm_export(struct device *child) @@ -44,16 +45,23 @@ static ssize_t period_show(struct device *child, struct device_attribute *attr, char *buf) { - const struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_export *export = child_to_pwm_export(child); + const struct pwm_device *pwm = export->pwm; + unsigned int period; + + mutex_lock(&export->lock); + period = pwm_get_period(pwm); + mutex_unlock(&export->lock); - return sprintf(buf, "%u\n", pwm_get_period(pwm)); + return sprintf(buf, "%u\n", period); } static ssize_t period_store(struct device *child, struct device_attribute *attr, const char *buf, size_t size) { - struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_export *export = child_to_pwm_export(child); + struct pwm_device *pwm = export->pwm; unsigned int val; int ret; @@ -61,7 +69,9 @@ static ssize_t period_store(struct device *child, if (ret) return ret; + mutex_lock(&export->lock); ret = pwm_config(pwm, pwm_get_duty_cycle(pwm), val); + mutex_unlock(&export->lock); return ret ? : size; } @@ -70,16 +80,23 @@ static ssize_t duty_cycle_show(struct device *child, struct device_attribute *attr, char *buf) { - const struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_export *export = child_to_pwm_export(child); + const struct pwm_device *pwm = export->pwm; + unsigned int duty; + + mutex_lock(&export->lock); + duty = pwm_get_duty_cycle(pwm); + mutex_unlock(&export->lock); - return sprintf(buf, "%u\n", pwm_get_duty_cycle(pwm)); + return sprintf(buf, "%u\n", duty); } static ssize_t duty_cycle_store(struct device *child, struct device_attribute *attr, const char *buf, size_t size) { - struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_export *export = child_to_pwm_export(child); + struct pwm_device *pwm = export->pwm; unsigned int val; int ret; @@ -87,7 +104,9 @@ static ssize_t duty_cycle_store(struct device *child, if (ret) return ret; + mutex_lock(&export->lock); ret = pwm_config(pwm, val, pwm_get_period(pwm)); + mutex_unlock(&export->lock); return ret ? : size; } @@ -96,22 +115,30 @@ static ssize_t enable_show(struct device *child, struct device_attribute *attr, char *buf) { - const struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_export *export = child_to_pwm_export(child); + const struct pwm_device *pwm = export->pwm; + bool enabled; + + mutex_lock(&export->lock); + enabled = pwm_is_enabled(pwm); + mutex_unlock(&export->lock); - return sprintf(buf, "%d\n", pwm_is_enabled(pwm)); + return sprintf(buf, "%d\n", enabled); } static ssize_t enable_store(struct device *child, struct device_attribute *attr, const char *buf, size_t size) { - struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_export *export = child_to_pwm_export(child); + struct pwm_device *pwm = export->pwm; int val, ret; ret = kstrtoint(buf, 0, &val); if (ret) return ret; + mutex_lock(&export->lock); switch (val) { case 0: pwm_disable(pwm); @@ -123,6 +150,7 @@ static ssize_t enable_store(struct device *child, ret = -EINVAL; break; } + mutex_unlock(&export->lock); return ret ? : size; } @@ -131,9 +159,11 @@ static ssize_t polarity_show(struct device *child, struct device_attribute *attr, char *buf) { - const struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_export *export = child_to_pwm_export(child); + const struct pwm_device *pwm = export->pwm; const char *polarity = "unknown"; + mutex_lock(&export->lock); switch (pwm_get_polarity(pwm)) { case PWM_POLARITY_NORMAL: polarity = "normal"; @@ -143,6 +173,7 @@ static ssize_t polarity_show(struct device *child, polarity = "inversed"; break; } + mutex_unlock(&export->lock); return sprintf(buf, "%s\n", polarity); } @@ -151,7 +182,8 @@ static ssize_t polarity_store(struct device *child, struct device_attribute *attr, const char *buf, size_t size) { - struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_export *export = child_to_pwm_export(child); + struct pwm_device *pwm = export->pwm; enum pwm_polarity polarity; int ret; @@ -162,7 +194,9 @@ static ssize_t polarity_store(struct device *child, else return -EINVAL; + mutex_lock(&export->lock); ret = pwm_set_polarity(pwm, polarity); + mutex_unlock(&export->lock); return ret ? : size; } @@ -203,6 +237,7 @@ static int pwm_export_child(struct device *parent, struct pwm_device *pwm) } export->pwm = pwm; + mutex_init(&export->lock); export->child.release = pwm_export_release; export->child.parent = parent; diff --git a/include/linux/pwm.h b/include/linux/pwm.h index cfc3ed4..6555f01 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -88,7 +88,6 @@ enum { * @pwm: global index of the PWM device * @chip: PWM chip providing this PWM device * @chip_data: chip-private data associated with the PWM device - * @lock: used to serialize accesses to the PWM device where necessary * @period: period of the PWM signal (in nanoseconds) * @duty_cycle: duty cycle of the PWM signal (in nanoseconds) * @polarity: polarity of the PWM signal @@ -100,7 +99,6 @@ struct pwm_device { unsigned int pwm; struct pwm_chip *chip; void *chip_data; - struct mutex lock; unsigned int period; unsigned int duty_cycle;