From nobody Thu Dec 25 23:29:05 2025 Received: from mail-wr1-f51.google.com (mail-wr1-f51.google.com [209.85.221.51]) (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 C80A84F1F8 for ; Wed, 10 Jan 2024 20:32:31 +0000 (UTC) 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="Vs9z/HE+" Received: by mail-wr1-f51.google.com with SMTP id ffacd0b85a97d-33678156e27so4083817f8f.1 for ; Wed, 10 Jan 2024 12:32:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1704918750; x=1705523550; 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=S4/ezTEXd/AGBE5ik3GQsGbwKaC7ixzvP0QmPnIVxHs=; b=Vs9z/HE+Iml7oygN16KpVcLUD5nh3xPNOH4zCK/oqxz+gbqVU9g1d2F/JZLszjYYet xiPC99nhFAcUDyq5M0+3zmH3LbTUDGkaZZPukzeWY+vcLskJxvC5b/YfX+3NXqOKLFBS JHk3jvW/XGam28Fz6YY0V9GCah8zB4QDBgCI/gqaBvwtlqVtgCAU3i8LinYCIBtdP3Gy L22NFuyW6CPCi/0mOwH92amTrcjiqQUq2IBzFxVQVpfn1yVrRJ9SsDPIcGThMI13qZZN +3ZWz6xNuz7N3ctV8xbOeAGJiL2nMLXBQbUpvjOLFxjYwvy08qt8BcYIwwWkqmOl5o4U zxwQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1704918750; x=1705523550; 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=S4/ezTEXd/AGBE5ik3GQsGbwKaC7ixzvP0QmPnIVxHs=; b=XOGbmdega2BizlWoqLi9R9FuwDNS8U1ZD2KU8+LsKj+lx6NWksIGOuEtlS3s1FNg/b kChsHQPx/duL4ngjA5SxJU+avpl279cV1oKupJPAUFAi/PmUfc2t0A/odxzac7dZ88Vo XJwQwmtvjZHVbwJAewc03b3jBSheXAahoEprCS96qLRRMGApy+6tYSTCEjSE+HUSs5Z0 8bgJCx/fgU0B0N1fPezZCMndjFZPDJuEFMFYY995uY/wV/Q7BQc5yCe+m+5/HiZ/2ULq vW602tGfDGHbtM64ZUBfVSI1sNgintl+O10Kw914yt8Fxbp8rfqezce1g0R6ehhvDgnO UN0A== X-Gm-Message-State: AOJu0YwWnVgxDr7Zqi4PoMlwOsLZ/5UZbXtfdwzVZXzYh3zVpRRXGWaO NwQgGHR0suR3OCoAVHZBlQrsbvlfDk0QWw== X-Google-Smtp-Source: AGHT+IG+Jh12VyGYmoVwBM+LMkw8YhuNMET4WndcS7w4Xu8ew7js3y1dau1a7gKopoa/qzRbjPgQ4w== X-Received: by 2002:a05:6000:372:b0:337:4758:43ef with SMTP id f18-20020a056000037200b00337475843efmr29206wrf.66.1704918750199; Wed, 10 Jan 2024 12:32:30 -0800 (PST) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:3342:1411:3dd8:cb70]) by smtp.gmail.com with ESMTPSA id z17-20020a5d44d1000000b003377e22ffdcsm2072172wrr.85.2024.01.10.12.32.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jan 2024 12:32:29 -0800 (PST) From: Bartosz Golaszewski To: Linus Walleij , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Boqun Feng Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH 1/3] cleanup: provide DEFINE_LOCK_GUARD_ARGS() Date: Wed, 10 Jan 2024 21:32:13 +0100 Message-Id: <20240110203215.36396-2-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240110203215.36396-1-brgl@bgdev.pl> References: <20240110203215.36396-1-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 This macro allows defining lock guard with additional arguments that can be passed to the locking function. This is useful for implementing guards for nested locking. Signed-off-by: Bartosz Golaszewski --- include/linux/cleanup.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h index c2d09bc4f976..921db45023bb 100644 --- a/include/linux/cleanup.h +++ b/include/linux/cleanup.h @@ -246,5 +246,11 @@ __DEFINE_LOCK_GUARD_0(_name, _lock) static inline void * class_##_name##_ext##_lock_ptr(class_##_name##_t *_T= ) \ { return class_##_name##_lock_ptr(_T); } =20 +/* + * Helper for implementing guard locks with additional arguments passed to + * the locking function. + */ +#define DEFINE_LOCK_GUARD_ARGS(_name, _type, _lock, _unlock, _args...) \ +DEFINE_CLASS(_name, _type, _unlock, ({ _lock; _T; }), _type _T, _args) =20 #endif /* __LINUX_GUARDS_H */ --=20 2.40.1 From nobody Thu Dec 25 23:29:05 2025 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) (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 05E814F1E0 for ; Wed, 10 Jan 2024 20:32:32 +0000 (UTC) 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="bcCeQTBW" Received: by mail-wm1-f51.google.com with SMTP id 5b1f17b1804b1-40e4d515c9aso33634135e9.0 for ; Wed, 10 Jan 2024 12:32:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1704918751; x=1705523551; 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=jEdTJOXkqBku2qR0TKwyio+JuDhgwS/A5uq4+eCSKZQ=; b=bcCeQTBWfoKOlwG0FkwOzeULj1ZofP2hzqB7URHPeBIIsqPM5GO5XT37K125t9WWZl FCReJEQzF2BKe4bSGiZfXfq7dW2mU/q3SfCD2zGXDvs9VlzJraJG4Ft2DuilwEDnwzn/ j9g7NlzP2VDiCwT4tVl1NFgrvm7rHYJVsnMey0gJavvWgLt3yCcHEn4rPFU0i0FVYI3k rKcSmJrCZSrhS+TBER8HMpSMjDwz3TQuvln4IJee/sTmn71r4Vz5ZpGwkKt+Dc8+l2kY hysjRa0BH1KxRz9Vr6fbv0yWzbExCbYc0aodi1PugV1B6NvzVOw/tPNBxBs6USpSS2HI dcqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1704918751; x=1705523551; 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=jEdTJOXkqBku2qR0TKwyio+JuDhgwS/A5uq4+eCSKZQ=; b=sZ2B1JrQiWjULZBZPijGzLGNdgtJgKPAleEMGSRin6/BjKtxVa1dKCQptRfMHya4eE gj9Ar6vKeInKrEEwF4hWhtZcfdpTpQ6fWo4UHS7czivZZtbmSsodm9uFFuna/1nh+Etm jvmNoB1z7AfZ9+3Pa7hYkJJAA3BRuOSNnEYNac8k5e82EAUT0k1eO9akbR3ylPGWnm6i kq+Tz93CIOTtTbFCG632xdYx/45VzsqO8+BGb/1pt6ncb0zJ2t813taUbKGS5PCruFDk /AqaKb03a0vMWvyY3hE7+xKycGLDoXgXDdA+NtH/Bsf3xkZxZk+N286myTdydJ7dWVcs DjhQ== X-Gm-Message-State: AOJu0YyxIihmCDwW0604SbAeH+fYmFm5scntR9KYIqHIrsGr7eCTKRrx PbRwC9c2bybaChWA6UUYxnJ/5gpuq+V1Fie0qqI8zjaUE58= X-Google-Smtp-Source: AGHT+IGOWnDjmizlbioxwpOowdqUvcfTZHld35bp2LkmBUxDT+Htv/cWEoB1XeBN+FcoMgHgbEqcWg== X-Received: by 2002:a05:600c:6c7:b0:40d:9369:697f with SMTP id b7-20020a05600c06c700b0040d9369697fmr904262wmn.144.1704918751227; Wed, 10 Jan 2024 12:32:31 -0800 (PST) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:3342:1411:3dd8:cb70]) by smtp.gmail.com with ESMTPSA id z17-20020a5d44d1000000b003377e22ffdcsm2072172wrr.85.2024.01.10.12.32.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jan 2024 12:32:30 -0800 (PST) From: Bartosz Golaszewski To: Linus Walleij , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Boqun Feng Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH 2/3] locking/rwsem: provide a lock guard for down_read_nested() Date: Wed, 10 Jan 2024 21:32:14 +0100 Message-Id: <20240110203215.36396-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240110203215.36396-1-brgl@bgdev.pl> References: <20240110203215.36396-1-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 This adds a lock guard for taking an RW semaphore for reading in nested context. It takes the nesting depth as a second argument. Signed-off-by: Bartosz Golaszewski --- include/linux/rwsem.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 9c29689ff505..298f5e60d30c 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -258,4 +258,10 @@ extern void up_read_non_owner(struct rw_semaphore *sem= ); # define up_read_non_owner(sem) up_read(sem) #endif =20 +DEFINE_LOCK_GUARD_ARGS(rwsem_read_nested, + struct rw_semaphore *, + down_read_nested(_T, subclass), + up_read(_T), + int subclass); + #endif /* _LINUX_RWSEM_H */ --=20 2.40.1 From nobody Thu Dec 25 23:29:05 2025 Received: from mail-wr1-f43.google.com (mail-wr1-f43.google.com [209.85.221.43]) (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 DA60F4EB34 for ; Wed, 10 Jan 2024 20:32:33 +0000 (UTC) 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="xbMqzXT6" Received: by mail-wr1-f43.google.com with SMTP id ffacd0b85a97d-33674f60184so4513333f8f.1 for ; Wed, 10 Jan 2024 12:32:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1704918752; x=1705523552; 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=xH5jTr5aU0xfloUoZ4e4ojWO1uQm4oQS8ylJSBoL6uQ=; b=xbMqzXT6stNQwOSGEF4TKGCpRnQOd6QT1tOh6Ce9t9voyBgxAQbeqB/S8wJXSGRDJS RB/em+pZk4qULwl1Fuq6n2XPEo6DeZkIxYedQsL3gitV6Q/e9kdutei0vih14x4YRLyI lkVdN3YA55zyo02h/u1LhgswVYQpfStxRXARRys85opSjTU28T7M2aCq/LltUDH4LbGk 82h42UHGy/8OFOS/IJz3LNwYcda4w15NUaxnsvWAfSiQxZSIQXzLMEoiuwY/uAAcENTg n23XxLg7GqiirQ5qARDff/GNkFWT0byJ1N8BxyVhTpc7jr/v6E4Izgf/S7Mw3ktPbcLW KmHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1704918752; x=1705523552; 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=xH5jTr5aU0xfloUoZ4e4ojWO1uQm4oQS8ylJSBoL6uQ=; b=DUoch9ADfzdXb/5g/OUEwV1m426hk3x+NTJZcpCt5UfOHMFYf10dndpiq1eeSoOJ2s HmbMeegCS8GEK1ooGKh1pcluUMezrO5cFJK4S/iMSUvMjiT7dQuD3P44RwJzlddxndVd 1L/HePeiI0PSvqRQq1+qHwO5zg7ji5aspzQAXoGxbpfwtWgR1uk4qidRtgO00yb2z42W ePdgP/rnWbrGqtew4dqyJtBUGhFPptPyyVlydgDz0pS9VENdIXBLCpqsUiCxTZkCO68e B9vveZtTyESe5oqfnjj0zzOXz3ydQN6Z98CqocxOPU47pXPhQaSY9tgLPymMQ9GrQuVy 5MgQ== X-Gm-Message-State: AOJu0YyJLK684qjueW9v+mpoo+/BVNMqQzXA5+f//DnT9yCIJoYc+chB TUHcxPrw/rXWJocf2j1Yj75xoGwBOVNr2g== X-Google-Smtp-Source: AGHT+IHuqat0eKssBubXT+iurOkhZRe56orJMHJGefWABPD4z8mSZqUu5SuIAslg9U0SLC0yT9YsNg== X-Received: by 2002:a5d:4f03:0:b0:336:7f45:bc0f with SMTP id c3-20020a5d4f03000000b003367f45bc0fmr29434wru.46.1704918752208; Wed, 10 Jan 2024 12:32:32 -0800 (PST) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:3342:1411:3dd8:cb70]) by smtp.gmail.com with ESMTPSA id z17-20020a5d44d1000000b003377e22ffdcsm2072172wrr.85.2024.01.10.12.32.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jan 2024 12:32:31 -0800 (PST) From: Bartosz Golaszewski To: Linus Walleij , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Boqun Feng Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH 3/3] gpiolib: pin GPIO devices in place during descriptor lookup Date: Wed, 10 Jan 2024 21:32:15 +0100 Message-Id: <20240110203215.36396-4-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240110203215.36396-1-brgl@bgdev.pl> References: <20240110203215.36396-1-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 There's time between when we locate the relevant descriptor during lookup and when we actually take the reference to its parent GPIO device where - if the GPIO device in question is removed - we'll end up with a dangling pointer to freed memory. Make sure devices cannot be removed until we hold a new reference to the device. In order to not overcomplicate the code with locking and unlocking variants of the same functions, just use the nesting feature of RW semaphores in gpio_device_find(). Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 42 ++++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 4c93cf73a826..972f33bc1a72 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1114,7 +1114,7 @@ struct gpio_device *gpio_device_find(void *data, */ might_sleep(); =20 - guard(rwsem_read)(&gpio_devices_sem); + guard(rwsem_read_nested)(&gpio_devices_sem, SINGLE_DEPTH_NESTING); =20 list_for_each_entry(gdev, &gpio_devices, list) { if (gdev->chip && match(gdev->chip, data)) @@ -4134,27 +4134,33 @@ static struct gpio_desc *gpiod_find_and_request(str= uct device *consumer, struct gpio_desc *desc; int ret; =20 - desc =3D gpiod_find_by_fwnode(fwnode, consumer, con_id, idx, &flags, &loo= kupflags); - if (gpiod_not_found(desc) && platform_lookup_allowed) { + scoped_guard(rwsem_read, &gpio_devices_sem) { + desc =3D gpiod_find_by_fwnode(fwnode, consumer, con_id, idx, + &flags, &lookupflags); + if (gpiod_not_found(desc) && platform_lookup_allowed) { + /* + * Either we are not using DT or ACPI, or their lookup + * did not return a result. In that case, use platform + * lookup as a fallback. + */ + dev_dbg(consumer, + "using lookup tables for GPIO lookup\n"); + desc =3D gpiod_find(consumer, con_id, idx, &lookupflags); + } + + if (IS_ERR(desc)) { + dev_dbg(consumer, "No GPIO consumer %s found\n", + con_id); + return desc; + } + /* - * Either we are not using DT or ACPI, or their lookup did not - * return a result. In that case, use platform lookup as a - * fallback. + * If a connection label was passed use that, else attempt to + * use the device name as label */ - dev_dbg(consumer, "using lookup tables for GPIO lookup\n"); - desc =3D gpiod_find(consumer, con_id, idx, &lookupflags); + ret =3D gpiod_request(desc, label); } =20 - if (IS_ERR(desc)) { - dev_dbg(consumer, "No GPIO consumer %s found\n", con_id); - return desc; - } - - /* - * If a connection label was passed use that, else attempt to use - * the device name as label - */ - ret =3D gpiod_request(desc, label); if (ret) { if (!(ret =3D=3D -EBUSY && flags & GPIOD_FLAGS_BIT_NONEXCLUSIVE)) return ERR_PTR(ret); --=20 2.40.1