{"id":2228942,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2228942/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-gpio/patch/20260427135841.96266-7-tzungbi@kernel.org/","project":{"id":42,"url":"http://patchwork.ozlabs.org/api/1.1/projects/42/?format=json","name":"Linux GPIO development","link_name":"linux-gpio","list_id":"linux-gpio.vger.kernel.org","list_email":"linux-gpio@vger.kernel.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260427135841.96266-7-tzungbi@kernel.org>","date":"2026-04-27T13:58:38","name":"[v9,6/9] gpio: Leverage revocable for accessing struct gpio_chip","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"88c9fb4df85cad526cb0a58b093df87315c22a0a","submitter":{"id":83557,"url":"http://patchwork.ozlabs.org/api/1.1/people/83557/?format=json","name":"Tzung-Bi Shih","email":"tzungbi@kernel.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-gpio/patch/20260427135841.96266-7-tzungbi@kernel.org/mbox/","series":[{"id":501655,"url":"http://patchwork.ozlabs.org/api/1.1/series/501655/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-gpio/list/?series=501655","date":"2026-04-27T13:58:32","name":"drivers/base: Introduce revocable","version":9,"mbox":"http://patchwork.ozlabs.org/series/501655/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2228942/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2228942/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-gpio@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=Oe0g0+R7;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; 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a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1777298393; cv=none;\n b=ZZKOcQrhX4lainu27MN4mbhjlcprxU+5+ym70r09zEKOv+Kvvg8zKykjWSZPx3Kk25MT5jYE/sDlc9Tq3uac/FOSBTxAaWkjOvlZPKjjWKvkn/mQPTaagmspjUODho0itCQS+5iaMIaVzqWeK3V6bqameTfHyy+xm3OFo8chDn8=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1777298393; c=relaxed/simple;\n\tbh=pi7ABDBl8gDgkbqRebEEglw8wiz3iI98IgsW5p9Mphk=;\n\th=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References:\n\t MIME-Version;\n b=G0eaxrJom4Kg4Ds+KYzVrBkSyBuQqOdMu4YWmPbzaPC1nBWiS33EMVf6oVhFPwVwGCNIU0GFAb43Q+PdiM6L3Z1ZMny8lXm7pDqZ1iFlrRyziLzzzRwOhMmkGCFRWfq9yFI1VQnOHiV+Hx1WB5qMbw9nQbLG8HvcWh9l/TmGtow=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=Oe0g0+R7; arc=none smtp.client-ip=10.30.226.201","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1777298392;\n\tbh=pi7ABDBl8gDgkbqRebEEglw8wiz3iI98IgsW5p9Mphk=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=Oe0g0+R7UODZhbNROLkQUVhVbBAGr/0Uid3Wb0CS4kp2EzoOFqAEyR7Aq/c8E9whv\n\t U/8Ew7FoQBLW5MaK58EVwJ8FXyHm6BiDx8PZ5+RsYOFa2DWV7BEFupEAi7W5lScWLM\n\t Hn9EsorGlTEKRMGM8wuz7soA30Y5o0N+nAItPNggV/VPUbTHhKsNEffsQ7pYU+0Hh6\n\t tJ5PrC92MTdC4uyPgfeO36k5h8yI7xAikcQLXqDWmpEUTbVsbObAHW32J7QSj90qf2\n\t vLiG2h+tzyK/WGxQYuxqXSIK4MrB7dThJrJWJAV9MUnVol/M9gmFhvNRRCh6aSTMlk\n\t e9JLBd+kDgYSw==","From":"Tzung-Bi Shih ","To":"Arnd Bergmann ,\n\tGreg Kroah-Hartman ,\n\tBartosz Golaszewski ,\n\tLinus Walleij ","Cc":"Benson Leung ,\n\ttzungbi@kernel.org,\n\tlinux-kernel@vger.kernel.org,\n\tchrome-platform@lists.linux.dev,\n\tdriver-core@lists.linux.dev,\n\tlinux-doc@vger.kernel.org,\n\tlinux-gpio@vger.kernel.org,\n\t\"Rafael J. Wysocki\" ,\n\tDanilo Krummrich ,\n\tJonathan Corbet ,\n\tShuah Khan ,\n\tLaurent Pinchart ,\n\tWolfram Sang ,\n\tJason Gunthorpe ,\n\tJohan Hovold ,\n\t\"Paul E . McKenney\" ,\n\tDan Williams ","Subject":"[PATCH v9 6/9] gpio: Leverage revocable for accessing struct\n 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-gpio@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit"},"content":"Struct gpio_device now provides a revocable provider to the underlying\nstruct gpio_chip. Leverage revocable for accessing the struct\ngpio_chip.\n\nSigned-off-by: Tzung-Bi Shih \n---\nv9:\n- New to the series.\n- Rename \"chip_rp\" -> \"chip_rev\".\n\nv4 - v8:\n- Doesn't exist.\n\nv3: https://lore.kernel.org/all/20260213092958.864411-11-tzungbi@kernel.org\n- Change revocable API usages accordingly.\n\nv2: https://lore.kernel.org/all/20260203061059.975605-11-tzungbi@kernel.org\n- Separate from v1(a) for excluding gpio_chip_guard and combine v1(b).\n\nv1(a):\n- https://lore.kernel.org/all/20260116081036.352286-23-tzungbi@kernel.org\nv1(b):\n- https://lore.kernel.org/all/20260116081036.352286-19-tzungbi@kernel.org\n\n---\n drivers/gpio/gpiolib.c | 60 +++++++++++++-----------------------------\n 1 file changed, 18 insertions(+), 42 deletions(-)","diff":"diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c\nindex 2cac1e15e1e5..798fd5f52745 100644\n--- a/drivers/gpio/gpiolib.c\n+++ b/drivers/gpio/gpiolib.c\n@@ -335,7 +335,10 @@ EXPORT_SYMBOL(gpio_device_get_label);\n */\n struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev)\n {\n-\treturn rcu_dereference_check(gdev->chip, 1);\n+\tstruct gpio_chip *gc;\n+\n+\trevocable_try_access_with(&gdev->chip_rev, gc);\n+\treturn gc;\n }\n EXPORT_SYMBOL_GPL(gpio_device_get_chip);\n \n@@ -561,9 +564,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)\n \n \tlist_for_each_entry_srcu(gdev, &gpio_devices, list,\n \t\t\t\t srcu_read_lock_held(&gpio_devices_srcu)) {\n-\t\tguard(srcu)(&gdev->srcu);\n-\n-\t\tgc = srcu_dereference(gdev->chip, &gdev->srcu);\n+\t\trevocable_try_access_with(&gdev->chip_rev, gc);\n \t\tif (!gc)\n \t\t\tcontinue;\n \n@@ -1050,9 +1051,7 @@ static void gpiochip_setup_devs(void)\n \n \tlist_for_each_entry_srcu(gdev, &gpio_devices, list,\n \t\t\t\t srcu_read_lock_held(&gpio_devices_srcu)) {\n-\t\tguard(srcu)(&gdev->srcu);\n-\n-\t\tgc = srcu_dereference(gdev->chip, &gdev->srcu);\n+\t\trevocable_try_access_with(&gdev->chip_rev, gc);\n \t\tif (!gc) {\n \t\t\tdev_err(&gdev->dev, \"Underlying GPIO chip is gone\\n\");\n \t\t\tcontinue;\n@@ -1455,11 +1454,11 @@ struct gpio_device *gpio_device_find(const void *data,\n \t\tif (!device_is_registered(&gdev->dev))\n \t\t\tcontinue;\n \n-\t\tguard(srcu)(&gdev->srcu);\n-\n-\t\tgc = srcu_dereference(gdev->chip, &gdev->srcu);\n+\t\trevocable_try_access_with(&gdev->chip_rev, gc);\n+\t\tif (!gc)\n+\t\t\tcontinue;\n \n-\t\tif (gc && match(gc, data))\n+\t\tif (match(gc, data))\n \t\t\treturn gpio_device_get(gdev);\n \t}\n \n@@ -3402,18 +3401,10 @@ static int gpio_chip_get_value(struct gpio_chip *gc, const struct gpio_desc *des\n \n static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)\n {\n-\tstruct gpio_device *gdev;\n \tstruct gpio_chip *gc;\n \tint value;\n \n-\t/* FIXME Unable to use gpio_chip_guard due to const desc. */\n-\tgdev = desc->gdev;\n-\n-\tguard(srcu)(&gdev->srcu);\n-\n-\tgc = srcu_dereference(gdev->chip, &gdev->srcu);\n-\tif (!gc)\n-\t\treturn -ENODEV;\n+\trevocable_try_access_or_return(&desc->gdev->chip_rev, gc);\n \n \tvalue = gpio_chip_get_value(gc, desc);\n \tvalue = value < 0 ? value : !!value;\n@@ -3452,9 +3443,10 @@ static int gpio_chip_get_multiple(struct gpio_chip *gc,\n /* The 'other' chip must be protected with its GPIO device's SRCU. */\n static bool gpio_device_chip_cmp(struct gpio_device *gdev, struct gpio_chip *gc)\n {\n-\tguard(srcu)(&gdev->srcu);\n+\tstruct gpio_chip *chip;\n \n-\treturn gc == srcu_dereference(gdev->chip, &gdev->srcu);\n+\trevocable_try_access_with(&gdev->chip_rev, chip);\n+\treturn chip ? chip == gc : false;\n }\n \n int gpiod_get_array_value_complex(bool raw, bool can_sleep,\n@@ -3477,11 +3469,7 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,\n \t\tif (!can_sleep)\n \t\t\tWARN_ON(array_info->gdev->can_sleep);\n \n-\t\tguard(srcu)(&array_info->gdev->srcu);\n-\t\tgc = srcu_dereference(array_info->gdev->chip,\n-\t\t\t\t &array_info->gdev->srcu);\n-\t\tif (!gc)\n-\t\t\treturn -ENODEV;\n+\t\trevocable_try_access_or_return(&array_info->gdev->chip_rev, gc);\n \n \t\tret = gpio_chip_get_multiple(gc, array_info->get_mask,\n \t\t\t\t\t value_bitmap);\n@@ -3818,11 +3806,7 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,\n \t\t\t\treturn -EPERM;\n \t\t}\n \n-\t\tguard(srcu)(&array_info->gdev->srcu);\n-\t\tgc = srcu_dereference(array_info->gdev->chip,\n-\t\t\t\t &array_info->gdev->srcu);\n-\t\tif (!gc)\n-\t\t\treturn -ENODEV;\n+\t\trevocable_try_access_or_return(&array_info->gdev->chip_rev, gc);\n \n \t\tif (!raw && !bitmap_empty(array_info->invert_mask, array_size))\n \t\t\tbitmap_xor(value_bitmap, value_bitmap,\n@@ -4117,7 +4101,6 @@ EXPORT_SYMBOL_GPL(gpiod_is_shared);\n */\n int gpiod_to_irq(const struct gpio_desc *desc)\n {\n-\tstruct gpio_device *gdev;\n \tstruct gpio_chip *gc;\n \tint offset;\n \tint ret;\n@@ -4126,12 +4109,7 @@ int gpiod_to_irq(const struct gpio_desc *desc)\n \tif (ret <= 0)\n \t\treturn -EINVAL;\n \n-\tgdev = desc->gdev;\n-\t/* FIXME Cannot use gpio_chip_guard due to const desc. */\n-\tguard(srcu)(&gdev->srcu);\n-\tgc = srcu_dereference(gdev->chip, &gdev->srcu);\n-\tif (!gc)\n-\t\treturn -ENODEV;\n+\trevocable_try_access_or_return(&desc->gdev->chip_rev, gc);\n \n \toffset = gpiod_hwgpio(desc);\n \tif (gc->to_irq) {\n@@ -5470,9 +5448,7 @@ static int gpiolib_seq_show(struct seq_file *s, void *v)\n \tif (priv->newline)\n \t\tseq_putc(s, '\\n');\n \n-\tguard(srcu)(&gdev->srcu);\n-\n-\tgc = srcu_dereference(gdev->chip, &gdev->srcu);\n+\trevocable_try_access_with(&gdev->chip_rev, gc);\n \tif (!gc) {\n \t\tseq_printf(s, \"%s: (dangling chip)\\n\", dev_name(&gdev->dev));\n \t\treturn 0;\n","prefixes":["v9","6/9"]}