From patchwork Thu Feb 20 10:01:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 1241342 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-gpio-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=bgdev.pl Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=bgdev-pl.20150623.gappssmtp.com header.i=@bgdev-pl.20150623.gappssmtp.com header.a=rsa-sha256 header.s=20150623 header.b=FJvt1dBi; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48NVVm6yg6z9sSL for ; Thu, 20 Feb 2020 21:01:52 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727840AbgBTKBw (ORCPT ); Thu, 20 Feb 2020 05:01:52 -0500 Received: from mail-wm1-f67.google.com ([209.85.128.67]:34903 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727705AbgBTKBu (ORCPT ); Thu, 20 Feb 2020 05:01:50 -0500 Received: by mail-wm1-f67.google.com with SMTP id b17so1338142wmb.0 for ; Thu, 20 Feb 2020 02:01:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=PxNamP/tY+VJSZ59R58OjGFNv8KfDwh59F4Xljb8y3g=; b=FJvt1dBidHKQ9i6NzW7D3scasMhmuxHzOekGkhyG1QrETE1a0KjWbaQb+C5iZSSyBA taIaO4VYqzahsrY7V4zWsc7+NzLmZiJHAIeBUNljknwYq3yk4fsKoU70gDwmrt8r+b4O kPDf28Xy/7PWbZsfzgXu+YqeDMALSj51asraPrJh/PKnyAR3B+rrH/hd+gYEOFPN9YH3 5jp+JWgbihgNGpsfEEg+OC0ZaUHPCNhoKIpleB1lCx+/ygsk0PwzDDZcVqf84kRTzSOl vEhY9HAPZk0QvprzPPbQKrAhMv4CW9A6iB3zj9iDUL7vis/TmnIvVxFyWW/OkRo5qBUL dcVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=PxNamP/tY+VJSZ59R58OjGFNv8KfDwh59F4Xljb8y3g=; b=FQ168UmjmtuwCAOywV6BwC3NgSx+aKsIVWJKTRN0l5ZkJ4VgCS7Ztik6DnwrNRDnZB JBfzgI711BADV9MSyz7+H15AREmTbrkdpLOcIQ8PoRaUk7M7E628bLHoRlT1TKnHcN2+ NRMOThLpZcLMBwJbleUifyJN7iTi0XyoA2kynF04Dk4kCHAim4jHKdCj03PVLcuGK+qM SFqOu7MGqeuoHSXDmoSmHZv4CwiS0kJrN+ThWiios/j5CPhzmaHPDHNlEo1SNmZs9QsW W3RX0+AWdsPiMoTTlcN4vNyw4zIfT4qUK+BUXiytzvNfzMKwEoRNiUfTailnB6ArxIKr uh7Q== X-Gm-Message-State: APjAAAWaqtzzPkIPao0egXoZjNH4wYhblRYmae0jM04ANMDOnbkK6GV8 7E7vxwXiOIY5+OKIMgUtQCBVJQ== X-Google-Smtp-Source: APXvYqywHwbPABTcol9PZLK4z7duQcvtOXJx1amFWGMSjrEKzVlTmOaPX0CLi7edYiQlkGUw8VP0cA== X-Received: by 2002:a05:600c:2503:: with SMTP id d3mr3431903wma.84.1582192907990; Thu, 20 Feb 2020 02:01:47 -0800 (PST) Received: from localhost.localdomain (lfbn-nic-1-188-94.w2-15.abo.wanadoo.fr. [2.15.37.94]) by smtp.gmail.com with ESMTPSA id z1sm3663496wmf.42.2020.02.20.02.01.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Feb 2020 02:01:47 -0800 (PST) From: Bartosz Golaszewski To: Linus Walleij , Srinivas Kandagatla , Khouloud Touil , Geert Uytterhoeven Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH v4 2/4] gpiolib: use kref in gpio_desc Date: Thu, 20 Feb 2020 11:01:39 +0100 Message-Id: <20200220100141.5905-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200220100141.5905-1-brgl@bgdev.pl> References: <20200220100141.5905-1-brgl@bgdev.pl> MIME-Version: 1.0 Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org From: Bartosz Golaszewski GPIO descriptors are freed by consumers using gpiod_put(). The name of this function suggests some reference counting is going on but it's not true. Use kref to actually introduce reference counting for gpio_desc objects. Add a corresponding gpiod_get() helper for increasing the reference count. This doesn't change anything for already existing (correct) drivers but allows us to keep track of GPIO descs used by multiple users. Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 36 ++++++++++++++++++++++++++++++++--- drivers/gpio/gpiolib.h | 1 + include/linux/gpio/consumer.h | 1 + 3 files changed, 35 insertions(+), 3 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 753283486037..42f820356279 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2798,6 +2798,8 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label) goto done; } + kref_init(&desc->ref); + if (chip->request) { /* chip->request may sleep */ spin_unlock_irqrestore(&gpio_lock, flags); @@ -2933,6 +2935,13 @@ void gpiod_free(struct gpio_desc *desc) } } +static void gpiod_free_kref(struct kref *ref) +{ + struct gpio_desc *desc = container_of(ref, struct gpio_desc, ref); + + gpiod_free(desc); +} + /** * gpiochip_is_requested - return string iff signal was requested * @chip: controller managing the signal @@ -5047,18 +5056,39 @@ struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev, EXPORT_SYMBOL_GPL(gpiod_get_array_optional); /** - * gpiod_put - dispose of a GPIO descriptor - * @desc: GPIO descriptor to dispose of + * gpiod_put - decrease the reference count of a GPIO descriptor + * @desc: GPIO descriptor to unref * * No descriptor can be used after gpiod_put() has been called on it. */ void gpiod_put(struct gpio_desc *desc) { if (desc) - gpiod_free(desc); + kref_put(&desc->ref, gpiod_free_kref); } EXPORT_SYMBOL_GPL(gpiod_put); +/** + * gpiod_ref - increase the reference count of a GPIO descriptor + * @desc: GPIO descriptor to reference + * + * Returns the same gpio_desc after increasing the reference count. + */ +struct gpio_desc *gpiod_ref(struct gpio_desc *desc) +{ + if (!desc) + return NULL; + + if (!test_bit(FLAG_REQUESTED, &desc->flags)) { + pr_warn("gpiolib: unable to increase the reference count of unrequested GPIO descriptor\n"); + return desc; + } + + kref_get(&desc->ref); + return desc; +} +EXPORT_SYMBOL_GPL(gpiod_ref); + /** * gpiod_put_array - dispose of multiple GPIO descriptors * @descs: struct gpio_descs containing an array of descriptors diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 3e0aab2945d8..51a92c43dd55 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -119,6 +119,7 @@ struct gpio_desc { const char *label; /* Name of the GPIO */ const char *name; + struct kref ref; }; int gpiod_request(struct gpio_desc *desc, const char *label); diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index bf2d017dd7b7..c7b5fb3d9d64 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -81,6 +81,7 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev, struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev, const char *con_id, enum gpiod_flags flags); +struct gpio_desc *gpiod_ref(struct gpio_desc *desc); void gpiod_put(struct gpio_desc *desc); void gpiod_put_array(struct gpio_descs *descs);