From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 166E13D1718; Mon, 27 Apr 2026 13:59:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777298393; cv=none; b=ZZKOcQrhX4lainu27MN4mbhjlcprxU+5+ym70r09zEKOv+Kvvg8zKykjWSZPx3Kk25MT5jYE/sDlc9Tq3uac/FOSBTxAaWkjOvlZPKjjWKvkn/mQPTaagmspjUODho0itCQS+5iaMIaVzqWeK3V6bqameTfHyy+xm3OFo8chDn8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777298393; c=relaxed/simple; bh=pi7ABDBl8gDgkbqRebEEglw8wiz3iI98IgsW5p9Mphk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=G0eaxrJom4Kg4Ds+KYzVrBkSyBuQqOdMu4YWmPbzaPC1nBWiS33EMVf6oVhFPwVwGCNIU0GFAb43Q+PdiM6L3Z1ZMny8lXm7pDqZ1iFlrRyziLzzzRwOhMmkGCFRWfq9yFI1VQnOHiV+Hx1WB5qMbw9nQbLG8HvcWh9l/TmGtow= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Oe0g0+R7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Oe0g0+R7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36F9DC2BCB9; Mon, 27 Apr 2026 13:59:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777298392; bh=pi7ABDBl8gDgkbqRebEEglw8wiz3iI98IgsW5p9Mphk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Oe0g0+R7UODZhbNROLkQUVhVbBAGr/0Uid3Wb0CS4kp2EzoOFqAEyR7Aq/c8E9whv U/8Ew7FoQBLW5MaK58EVwJ8FXyHm6BiDx8PZ5+RsYOFa2DWV7BEFupEAi7W5lScWLM Hn9EsorGlTEKRMGM8wuz7soA30Y5o0N+nAItPNggV/VPUbTHhKsNEffsQ7pYU+0Hh6 tJ5PrC92MTdC4uyPgfeO36k5h8yI7xAikcQLXqDWmpEUTbVsbObAHW32J7QSj90qf2 vLiG2h+tzyK/WGxQYuxqXSIK4MrB7dThJrJWJAV9MUnVol/M9gmFhvNRRCh6aSTMlk e9JLBd+kDgYSw== From: Tzung-Bi Shih To: Arnd Bergmann , Greg Kroah-Hartman , Bartosz Golaszewski , Linus Walleij Cc: Benson Leung , tzungbi@kernel.org, linux-kernel@vger.kernel.org, chrome-platform@lists.linux.dev, driver-core@lists.linux.dev, linux-doc@vger.kernel.org, linux-gpio@vger.kernel.org, "Rafael J. Wysocki" , Danilo Krummrich , Jonathan Corbet , Shuah Khan , Laurent Pinchart , Wolfram Sang , Jason Gunthorpe , Johan Hovold , "Paul E . McKenney" , Dan Williams Subject: [PATCH v9 6/9] gpio: Leverage revocable for accessing struct gpio_chip Date: Mon, 27 Apr 2026 21:58:38 +0800 Message-ID: <20260427135841.96266-7-tzungbi@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260427135841.96266-1-tzungbi@kernel.org> References: <20260427135841.96266-1-tzungbi@kernel.org> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Struct gpio_device now provides a revocable provider to the underlying struct gpio_chip. Leverage revocable for accessing the struct gpio_chip. Signed-off-by: Tzung-Bi Shih --- v9: - New to the series. - Rename "chip_rp" -> "chip_rev". v4 - v8: - Doesn't exist. v3: https://lore.kernel.org/all/20260213092958.864411-11-tzungbi@kernel.org - Change revocable API usages accordingly. v2: https://lore.kernel.org/all/20260203061059.975605-11-tzungbi@kernel.org - Separate from v1(a) for excluding gpio_chip_guard and combine v1(b). v1(a): - https://lore.kernel.org/all/20260116081036.352286-23-tzungbi@kernel.org v1(b): - https://lore.kernel.org/all/20260116081036.352286-19-tzungbi@kernel.org --- drivers/gpio/gpiolib.c | 60 +++++++++++++----------------------------- 1 file changed, 18 insertions(+), 42 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 2cac1e15e1e5..798fd5f52745 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -335,7 +335,10 @@ EXPORT_SYMBOL(gpio_device_get_label); */ struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev) { - return rcu_dereference_check(gdev->chip, 1); + struct gpio_chip *gc; + + revocable_try_access_with(&gdev->chip_rev, gc); + return gc; } EXPORT_SYMBOL_GPL(gpio_device_get_chip); @@ -561,9 +564,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name) list_for_each_entry_srcu(gdev, &gpio_devices, list, srcu_read_lock_held(&gpio_devices_srcu)) { - guard(srcu)(&gdev->srcu); - - gc = srcu_dereference(gdev->chip, &gdev->srcu); + revocable_try_access_with(&gdev->chip_rev, gc); if (!gc) continue; @@ -1050,9 +1051,7 @@ static void gpiochip_setup_devs(void) list_for_each_entry_srcu(gdev, &gpio_devices, list, srcu_read_lock_held(&gpio_devices_srcu)) { - guard(srcu)(&gdev->srcu); - - gc = srcu_dereference(gdev->chip, &gdev->srcu); + revocable_try_access_with(&gdev->chip_rev, gc); if (!gc) { dev_err(&gdev->dev, "Underlying GPIO chip is gone\n"); continue; @@ -1455,11 +1454,11 @@ struct gpio_device *gpio_device_find(const void *data, if (!device_is_registered(&gdev->dev)) continue; - guard(srcu)(&gdev->srcu); - - gc = srcu_dereference(gdev->chip, &gdev->srcu); + revocable_try_access_with(&gdev->chip_rev, gc); + if (!gc) + continue; - if (gc && match(gc, data)) + if (match(gc, data)) return gpio_device_get(gdev); } @@ -3402,18 +3401,10 @@ static int gpio_chip_get_value(struct gpio_chip *gc, const struct gpio_desc *des static int gpiod_get_raw_value_commit(const struct gpio_desc *desc) { - struct gpio_device *gdev; struct gpio_chip *gc; int value; - /* FIXME Unable to use gpio_chip_guard due to const desc. */ - gdev = desc->gdev; - - guard(srcu)(&gdev->srcu); - - gc = srcu_dereference(gdev->chip, &gdev->srcu); - if (!gc) - return -ENODEV; + revocable_try_access_or_return(&desc->gdev->chip_rev, gc); value = gpio_chip_get_value(gc, desc); value = value < 0 ? value : !!value; @@ -3452,9 +3443,10 @@ static int gpio_chip_get_multiple(struct gpio_chip *gc, /* The 'other' chip must be protected with its GPIO device's SRCU. */ static bool gpio_device_chip_cmp(struct gpio_device *gdev, struct gpio_chip *gc) { - guard(srcu)(&gdev->srcu); + struct gpio_chip *chip; - return gc == srcu_dereference(gdev->chip, &gdev->srcu); + revocable_try_access_with(&gdev->chip_rev, chip); + return chip ? chip == gc : false; } int gpiod_get_array_value_complex(bool raw, bool can_sleep, @@ -3477,11 +3469,7 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep, if (!can_sleep) WARN_ON(array_info->gdev->can_sleep); - guard(srcu)(&array_info->gdev->srcu); - gc = srcu_dereference(array_info->gdev->chip, - &array_info->gdev->srcu); - if (!gc) - return -ENODEV; + revocable_try_access_or_return(&array_info->gdev->chip_rev, gc); ret = gpio_chip_get_multiple(gc, array_info->get_mask, value_bitmap); @@ -3818,11 +3806,7 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep, return -EPERM; } - guard(srcu)(&array_info->gdev->srcu); - gc = srcu_dereference(array_info->gdev->chip, - &array_info->gdev->srcu); - if (!gc) - return -ENODEV; + revocable_try_access_or_return(&array_info->gdev->chip_rev, gc); if (!raw && !bitmap_empty(array_info->invert_mask, array_size)) bitmap_xor(value_bitmap, value_bitmap, @@ -4117,7 +4101,6 @@ EXPORT_SYMBOL_GPL(gpiod_is_shared); */ int gpiod_to_irq(const struct gpio_desc *desc) { - struct gpio_device *gdev; struct gpio_chip *gc; int offset; int ret; @@ -4126,12 +4109,7 @@ int gpiod_to_irq(const struct gpio_desc *desc) if (ret <= 0) return -EINVAL; - gdev = desc->gdev; - /* FIXME Cannot use gpio_chip_guard due to const desc. */ - guard(srcu)(&gdev->srcu); - gc = srcu_dereference(gdev->chip, &gdev->srcu); - if (!gc) - return -ENODEV; + revocable_try_access_or_return(&desc->gdev->chip_rev, gc); offset = gpiod_hwgpio(desc); if (gc->to_irq) { @@ -5470,9 +5448,7 @@ static int gpiolib_seq_show(struct seq_file *s, void *v) if (priv->newline) seq_putc(s, '\n'); - guard(srcu)(&gdev->srcu); - - gc = srcu_dereference(gdev->chip, &gdev->srcu); + revocable_try_access_with(&gdev->chip_rev, gc); if (!gc) { seq_printf(s, "%s: (dangling chip)\n", dev_name(&gdev->dev)); return 0; -- 2.51.0