From patchwork Tue Jan 30 12:48:13 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 768660 Received: from mail-wm1-f44.google.com (mail-wm1-f44.google.com [209.85.128.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DEF8D6DCE8 for ; Tue, 30 Jan 2024 12:48:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.44 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706618929; cv=none; b=dAs0hnEn6AY06QaO5CirXJFSip3cu5hzgTg+QA2Q3Oua/KGvqHuTn73HcXGO5Qym9z+TY3xKB6WsrbW1GBgy16YCfFswiDgaFyg6zCL3GF3uujrRAHxMsCAIRjhsefwKfp/F2f2UBDxnjkDUKmD/M5xVZ0Ec5j9CixASf0Vf/gk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706618929; c=relaxed/simple; bh=tRtObxZogumFOl4YzKALlA4fMdN1FOxf6e/M7HZm0V8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=os/EkFkvO0uKVk/ZCsgb/22bg5Zph26OtW1Rv8m/0Tp0+v4Q72luwUFpAByOQdhCX4e84GTIyVL/vqtfpkhRU6/+OT6yksbkhBJ9K847LHqzhRQShBBAejkAwFCPIZoOd28AKbypMguhkCN+lM9b1V44NgdNrNablU94D9spX9U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=bgdev.pl; spf=none smtp.mailfrom=bgdev.pl; dkim=pass (2048-bit key) header.d=bgdev-pl.20230601.gappssmtp.com header.i=@bgdev-pl.20230601.gappssmtp.com header.b=2JXQuAWn; arc=none smtp.client-ip=209.85.128.44 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=bgdev.pl Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bgdev.pl Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bgdev-pl.20230601.gappssmtp.com header.i=@bgdev-pl.20230601.gappssmtp.com header.b="2JXQuAWn" Received: by mail-wm1-f44.google.com with SMTP id 5b1f17b1804b1-40ef6da20feso12017255e9.0 for ; Tue, 30 Jan 2024 04:48:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1706618926; x=1707223726; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Yf4hrLbZWsC4ubgIBbzrDZoZfZtu8JUtSDXYHSjq/J0=; b=2JXQuAWnU96tv13Su1OcRgd20fYYF/Gu6siK635XeVJdJ8VZLbNQd8n15whsibcBwZ 2pex6PpAfMm0OkYSvgcrf9D/kUZ58fgqrqbuIDsHP4IBnQCnYTXNiqdo6geI/pKAYKco QqiiO9kyh9Je4dCJ9K0eef6mmg5oMyI4yj1FEGyW5Q1IpdO/AcK3jxFGrpIMT/ti9sY9 lRVm5cNw9yFDfjK09HJLCAVUpk8IiTQJTVbHHs7faEMIm3SD9U9j4yeFHvhXf+JTDWma mRlPtCGJZHg9QKSPtYuugH3NwvG/KDOqu8y831c0scYnPeLomF/YRfuXg3m/pJCx3pTc pJaw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706618926; x=1707223726; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Yf4hrLbZWsC4ubgIBbzrDZoZfZtu8JUtSDXYHSjq/J0=; b=BPCV4CTDyHphX+FmRUxQqw+U5OoKVh+k/Zbgq+iFoBsbI3T7sAkz+iVTQvnwSQl483 bAhJrnV75fJ80hrFZ/1ekD2SoyvQ3j5/Dd2CfqruvAfje5UKvlMoupaHSygZ2E+aIcmU xngy8p/o/OYupa9BuXRiLhBzhbHn5VSrcZBDJr76ARBikp2rQJUVa+d8HO1/U+LKYNb7 uhz0sa8T8NF5ppnFKDq2NUXw/xA3h8nZpdN84mHCermZ35cveJYTkc4DJSBgPt7uFH+V gvYN4SiA/KcT1YoPhSNeesnCfhWiAhTlcvZRbTVgAc1WQ/o57VGl0CPY2TpTSeW+S0+5 1NHQ== X-Gm-Message-State: AOJu0YxwLpWh8I6Q2z7rx2KfUmnPWRu1Nyf1N+d1iQlnIJgXYwJlzgTm EizVG7D2aAHXg1IqftUCnzF/cjw46i3ow0iCUfb9esz6nH8ylkawHqiRg3SBQpw= X-Google-Smtp-Source: AGHT+IEAAj583Hw/ycb3WalWDo1I5AHpvT5XQALiHrzIWF6PP92X1RGOXX4vViTzd9mzjQvxLVq+LA== X-Received: by 2002:a05:600c:1d86:b0:40e:f742:6330 with SMTP id p6-20020a05600c1d8600b0040ef7426330mr1493132wms.18.1706618926162; Tue, 30 Jan 2024 04:48:46 -0800 (PST) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:abc8:f77e:abeb:129c]) by smtp.gmail.com with ESMTPSA id en8-20020a056000420800b0033940016d6esm6625337wrb.93.2024.01.30.04.48.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jan 2024 04:48:45 -0800 (PST) From: Bartosz Golaszewski To: Linus Walleij , Kent Gibson , Alex Elder , Geert Uytterhoeven , "Paul E . McKenney" , Andy Shevchenko , Wolfram Sang Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH 07/22] gpio: protect the descriptor label with SRCU Date: Tue, 30 Jan 2024 13:48:13 +0100 Message-Id: <20240130124828.14678-8-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240130124828.14678-1-brgl@bgdev.pl> References: <20240130124828.14678-1-brgl@bgdev.pl> Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Bartosz Golaszewski In order to ensure that the label is not freed while it's being accessed, let's protect it with SRCU and synchronize it everytime it's changed. Let's modify desc_set_label() to manage the memory used for the label as it can only be freed once synchronize_srcu() returns. Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib-cdev.c | 10 +++++--- drivers/gpio/gpiolib.c | 47 +++++++++++++++++++++++-------------- drivers/gpio/gpiolib.h | 34 +++++++++++++++++++-------- 3 files changed, 61 insertions(+), 30 deletions(-) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index 2c0a0700762d..75f4912339a6 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -2297,6 +2297,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc, { struct gpio_chip *gc = desc->gdev->chip; unsigned long dflags; + const char *label; memset(info, 0, sizeof(*info)); info->offset = gpio_chip_hwgpio(desc); @@ -2305,9 +2306,12 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc, if (desc->name) strscpy(info->name, desc->name, sizeof(info->name)); - if (gpiod_get_label(desc)) - strscpy(info->consumer, gpiod_get_label(desc), - sizeof(info->consumer)); + scoped_guard(srcu, &desc->srcu) { + label = gpiod_get_label(desc); + if (label) + strscpy(info->consumer, label, + sizeof(info->consumer)); + } dflags = READ_ONCE(desc->flags); } diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 94e1a603cf8b..93b80f3e9fe2 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -114,12 +114,26 @@ const char *gpiod_get_label(struct gpio_desc *desc) !test_bit(FLAG_REQUESTED, &flags)) return "interrupt"; - return test_bit(FLAG_REQUESTED, &flags) ? desc->label : NULL; + return test_bit(FLAG_REQUESTED, &flags) ? + rcu_dereference(desc->label) : NULL; } -static inline void desc_set_label(struct gpio_desc *d, const char *label) +static int desc_set_label(struct gpio_desc *desc, const char *label) { - d->label = label; + const char *new = NULL, *old; + + if (label) { + /* FIXME: make this GFP_KERNEL once the spinlock is out. */ + new = kstrdup_const(label, GFP_ATOMIC); + if (!new) + return -ENOMEM; + } + + old = rcu_replace_pointer(desc->label, new, 1); + synchronize_srcu(&desc->srcu); + kfree_const(old); + + return 0; } /** @@ -2220,9 +2234,7 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label) * before IRQs are enabled, for non-sleeping (SOC) GPIOs. */ - if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) { - desc_set_label(desc, label ? : "?"); - } else { + if (test_and_set_bit(FLAG_REQUESTED, &desc->flags)) { ret = -EBUSY; goto out_free_unlock; } @@ -2250,6 +2262,13 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label) spin_lock_irqsave(&gpio_lock, flags); } spin_unlock_irqrestore(&gpio_lock, flags); + + ret = desc_set_label(desc, label ? : "?"); + if (ret) { + clear_bit(FLAG_REQUESTED, &desc->flags); + return ret; + } + return 0; out_free_unlock: @@ -2334,8 +2353,6 @@ static bool gpiod_free_commit(struct gpio_desc *desc) gc->free(gc, gpio_chip_hwgpio(desc)); spin_lock_irqsave(&gpio_lock, flags); } - kfree_const(desc->label); - desc_set_label(desc, NULL); clear_bit(FLAG_ACTIVE_LOW, &desc->flags); clear_bit(FLAG_REQUESTED, &desc->flags); clear_bit(FLAG_OPEN_DRAIN, &desc->flags); @@ -2353,6 +2370,7 @@ static bool gpiod_free_commit(struct gpio_desc *desc) } spin_unlock_irqrestore(&gpio_lock, flags); + desc_set_label(desc, NULL); gpiod_line_state_notify(desc, GPIOLINE_CHANGED_RELEASED); return ret; @@ -2400,6 +2418,8 @@ char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset) if (!test_bit(FLAG_REQUESTED, &desc->flags)) return NULL; + guard(srcu)(&desc->srcu); + /* * FIXME: Once we mark gpiod_direction_input/output() and * gpiod_get_direction() with might_sleep(), we'll be able to protect @@ -3511,16 +3531,8 @@ EXPORT_SYMBOL_GPL(gpiod_cansleep); int gpiod_set_consumer_name(struct gpio_desc *desc, const char *name) { VALIDATE_DESC(desc); - if (name) { - name = kstrdup_const(name, GFP_KERNEL); - if (!name) - return -ENOMEM; - } - kfree_const(desc->label); - desc_set_label(desc, name); - - return 0; + return desc_set_label(desc, name); } EXPORT_SYMBOL_GPL(gpiod_set_consumer_name); @@ -4726,6 +4738,7 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev) int value; for_each_gpio_desc(gc, desc) { + guard(srcu)(&desc->srcu); if (test_bit(FLAG_REQUESTED, &desc->flags)) { gpiod_get_direction(desc); is_out = test_bit(FLAG_IS_OUT, &desc->flags); diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 6e14b629c48b..d2e73eea9e92 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -180,7 +180,7 @@ struct gpio_desc { #define FLAG_EVENT_CLOCK_HTE 19 /* GPIO CDEV reports hardware timestamps in events */ /* Connection label */ - const char *label; + const char __rcu *label; /* Name of the GPIO */ const char *name; #ifdef CONFIG_OF_DYNAMIC @@ -223,15 +223,29 @@ static inline int gpio_chip_hwgpio(const struct gpio_desc *desc) /* With descriptor prefix */ -#define gpiod_err(desc, fmt, ...) \ - pr_err("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \ - ##__VA_ARGS__) -#define gpiod_warn(desc, fmt, ...) \ - pr_warn("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \ - ##__VA_ARGS__) -#define gpiod_dbg(desc, fmt, ...) \ - pr_debug("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?",\ - ##__VA_ARGS__) +#define gpiod_err(desc, fmt, ...) \ +do { \ + scoped_guard(srcu, &desc->srcu) { \ + pr_err("gpio-%d (%s): " fmt, desc_to_gpio(desc), \ + gpiod_get_label(desc) ? : "?", ##__VA_ARGS__); \ + } \ +} while (0) + +#define gpiod_warn(desc, fmt, ...) \ +do { \ + scoped_guard(srcu, &desc->srcu) { \ + pr_warn("gpio-%d (%s): " fmt, desc_to_gpio(desc), \ + gpiod_get_label(desc) ? : "?", ##__VA_ARGS__); \ + } \ +} while (0) + +#define gpiod_dbg(desc, fmt, ...) \ +do { \ + scoped_guard(srcu, &desc->srcu) { \ + pr_debug("gpio-%d (%s): " fmt, desc_to_gpio(desc), \ + gpiod_get_label(desc) ? : "?", ##__VA_ARGS__); \ + } \ +} while (0) /* With chip prefix */