From nobody Sun Feb 8 05:26:56 2026 Received: from mail-wm1-f45.google.com (mail-wm1-f45.google.com [209.85.128.45]) (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 E129013AED for ; Mon, 5 Feb 2024 09:34:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.45 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707125675; cv=none; b=K1fcy/5Iwga88Ct7sZiCbNjpverqLyOt6V/dh0UcCtCc86L5IB7WVTwNh1aVtXqn5QHbu1RllFYjr0G5S04130edHHK2/ytBk1K6KObgt9IgnBWZHLASeZiYYnd+kilvsi1RnnhRtGgSStB16jaeTXm3enVacZtCtZM70itF9IA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707125675; c=relaxed/simple; bh=Iu1ud2V7hAqRPw6qsJ4BEkBo20yGRwt6IVyG748uVng=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ql5yuhUqZDs1RppOskDnTE5UDbta8eX93HAE2jphG1EpRPVbXAfaoX0x/AuZ3OaLAQBCej+0p24/a2ibDTucWtZwTlShib9VlXJ4xpoM/Ai5Y5KPu41VNu+YC6Ku1m6jjrJxul5cDIUvGedKiDas5VXbLfZ3Srh5OIPETwgO3ks= 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=ocrqLTly; arc=none smtp.client-ip=209.85.128.45 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="ocrqLTly" Received: by mail-wm1-f45.google.com with SMTP id 5b1f17b1804b1-40fdd11475aso3070225e9.0 for ; Mon, 05 Feb 2024 01:34:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1707125672; x=1707730472; 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=SZKu4GUN8Mdrmtq+mCLkathjFvWJwZX/fdEUwbcMDKM=; b=ocrqLTlyHem20c2HZRIZRuPnZkX6vJXs3gzTELx+5TfKM2tkfIk72hkPB8VmNDYD4m baV8GCuD35Gkiec/lfL7mMWc+1gHV9o6XJB2BUcDemFK1I/KDuLrGatrhQbsN9qDEKbz +6OJwUibzIDSf+W8EHhcVbEEq0vlR3qEcSE6Le8OYZFQ3zJ95KT2o2eAM5hi5wZ0feVq w/74MwmtJ6Dv57u+5ckJoBbbENPPztRxJJoQieVglfd2NrK/Zl3k6w2KoglMfO79T3kn HoY+WBg2TovQRVpCpJfTCwp0q76QzLmritT8014t2Qxjy5E9S9rz0fPbR+WDsd6IJsl5 YiMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707125672; x=1707730472; 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=SZKu4GUN8Mdrmtq+mCLkathjFvWJwZX/fdEUwbcMDKM=; b=F+ZVn/ew1i063/wdQsde9fcGeZItLwDZrOD8h1T/XJoPDOFzbJtCCEXxyEfeqpQM4+ CKfUk1YmeU7xzBV3p4BJk6zfalLTDk26LDaHBIjqi8DxbCh5y0JV+oVcVzkhO2l4B1EY jf2KXYxWRMvg3wD7WM1geOkExfu/nWLxnPCTtfB0UpLlEc9gllbUVY9PlRbBw2x3l7mB 0FP6iqdH/UWd58/6wunfjGMyg4fGRaKSszDyPTC3e2WdHH66Lge5GCrg+TkGFpz6ExEw liGVic1UVV/ySM4WVVBwe3wgobmNifeaGKXpC5wf8dwdg0zTqU9doTfyzsxHyyCOpc18 7ikg== X-Gm-Message-State: AOJu0YxWNI8ud8/HMw7XjyKz9DTvTq3OGvy0w5cAEQ4ysPH1UPAHJra+ aM1zKjA6BnN6aW3CkUttkQJZoFMJPdUndtH07/2kAhhqkZw66HPscQOPnnb0+bc= X-Google-Smtp-Source: AGHT+IFDs25h1zo11JFYWw/lWaxEJX4khotrq6H9fGUlWGR98K+wisEz2DEBoU/sA+YMzz+RtVUYaQ== X-Received: by 2002:a05:600c:190f:b0:40f:ddc8:f801 with SMTP id j15-20020a05600c190f00b0040fddc8f801mr506301wmq.34.1707125672015; Mon, 05 Feb 2024 01:34:32 -0800 (PST) X-Forwarded-Encrypted: i=0; AJvYcCVWF4OPWhnyYDlGIv9CoNgJBcAmGOGu4ZDCZ/I3ZjxRyQjJY6xv0cL40qoBgpJYceHqbjp7DG4VWbAQq7dcExpzxlkGQZkW04j6VWRnfm/UMGkzxEQ2b83rP+u8/z7qlIH9WkSxHHjqGkuPoPJk7sS2c6UWBtJGTctulhKyUGl4wG2PNk0InO3RiABpcHD+9T9+G/q/gA0uh+TZUfosdgkOxwKjf6JgCE7W4ENJMHlse6iRE6yY3nXpGO6Ey9bUZIKmOpaEmsxjwuqlePYcRWximBuS2hXvy5ToMcFcLjUIYINzPS/OETEA2sMm4dwPI7Pf11U0lo2YPZYt7LzmH8ZbuLoDGBb5tA== Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:d929:10db:5b5c:b49d]) by smtp.gmail.com with ESMTPSA id f15-20020a05600c154f00b0040fc771c864sm7980397wmg.14.2024.02.05.01.34.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Feb 2024 01:34:31 -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 v2 07/23] gpio: protect the descriptor label with SRCU Date: Mon, 5 Feb 2024 10:34:02 +0100 Message-Id: <20240205093418.39755-8-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240205093418.39755-1-brgl@bgdev.pl> References: <20240205093418.39755-1-brgl@bgdev.pl> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Linus Walleij --- 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 *d= esc, { struct gpio_chip *gc =3D desc->gdev->chip; unsigned long dflags; + const char *label; =20 memset(info, 0, sizeof(*info)); info->offset =3D 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)); =20 - if (gpiod_get_label(desc)) - strscpy(info->consumer, gpiod_get_label(desc), - sizeof(info->consumer)); + scoped_guard(srcu, &desc->srcu) { + label =3D gpiod_get_label(desc); + if (label) + strscpy(info->consumer, label, + sizeof(info->consumer)); + } =20 dflags =3D READ_ONCE(desc->flags); } diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index ea0c0158faaf..f425e0264b7e 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"; =20 - return test_bit(FLAG_REQUESTED, &flags) ? desc->label : NULL; + return test_bit(FLAG_REQUESTED, &flags) ? + rcu_dereference(desc->label) : NULL; } =20 -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 =3D label; + const char *new =3D NULL, *old; + + if (label) { + /* FIXME: make this GFP_KERNEL once the spinlock is out. */ + new =3D kstrdup_const(label, GFP_ATOMIC); + if (!new) + return -ENOMEM; + } + + old =3D rcu_replace_pointer(desc->label, new, 1); + synchronize_srcu(&desc->srcu); + kfree_const(old); + + return 0; } =20 /** @@ -2223,9 +2237,7 @@ static int gpiod_request_commit(struct gpio_desc *des= c, const char *label) * before IRQs are enabled, for non-sleeping (SOC) GPIOs. */ =20 - if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) =3D=3D 0) { - desc_set_label(desc, label ? : "?"); - } else { + if (test_and_set_bit(FLAG_REQUESTED, &desc->flags)) { ret =3D -EBUSY; goto out_free_unlock; } @@ -2253,6 +2265,13 @@ static int gpiod_request_commit(struct gpio_desc *de= sc, const char *label) spin_lock_irqsave(&gpio_lock, flags); } spin_unlock_irqrestore(&gpio_lock, flags); + + ret =3D desc_set_label(desc, label ? : "?"); + if (ret) { + clear_bit(FLAG_REQUESTED, &desc->flags); + return ret; + } + return 0; =20 out_free_unlock: @@ -2337,8 +2356,6 @@ 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); @@ -2356,6 +2373,7 @@ static bool gpiod_free_commit(struct gpio_desc *desc) } =20 spin_unlock_irqrestore(&gpio_lock, flags); + desc_set_label(desc, NULL); gpiod_line_state_notify(desc, GPIOLINE_CHANGED_RELEASED); =20 return ret; @@ -2403,6 +2421,8 @@ char *gpiochip_dup_line_label(struct gpio_chip *gc, u= nsigned int offset) if (!test_bit(FLAG_REQUESTED, &desc->flags)) return NULL; =20 + 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 @@ -3514,16 +3534,8 @@ EXPORT_SYMBOL_GPL(gpiod_cansleep); int gpiod_set_consumer_name(struct gpio_desc *desc, const char *name) { VALIDATE_DESC(desc); - if (name) { - name =3D kstrdup_const(name, GFP_KERNEL); - if (!name) - return -ENOMEM; - } =20 - kfree_const(desc->label); - desc_set_label(desc, name); - - return 0; + return desc_set_label(desc, name); } EXPORT_SYMBOL_GPL(gpiod_set_consumer_name); =20 @@ -4733,6 +4745,7 @@ static void gpiolib_dbg_show(struct seq_file *s, stru= ct gpio_device *gdev) int value; =20 for_each_gpio_desc(gc, desc) { + guard(srcu)(&desc->srcu); if (test_bit(FLAG_REQUESTED, &desc->flags)) { gpiod_get_direction(desc); is_out =3D 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 */ =20 /* 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) =20 /* With descriptor prefix */ =20 -#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) =20 /* With chip prefix */ =20 --=20 2.40.1