From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793635260; b=gziGFH6rj2BSiZx3sryrBjb2+5lE0o5OZnLQhQXaaIxpqjtGrThNJ72Sg4ZvpF3lriDT IDkPcAs6pU6y2MOzT82zU84ijJyfC4R2PiLUPKg6PA2zOhgzc6khNmT7KYclqkXunXSP6 HE/AKfJTqm/uNO72bElV3Neap5MqAGftzSPTMzhb4VDq1msf2gBEZq/PNZiLs+YJbb8rz F3D7zg6nlQcig2Y+UVLppR4UpoY6K9RSUzQW0Znig3xW3bxpRBvZd0AWr2Gt9ABNM/ttw T7G/F/ChTXj/JHph6hMq1+anlcfYudkvZsrLsFEp0xjYaiCZqO2ZQnqIaJ8q2G22miQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793635260; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=z5QV5L82RZqkGo+Xib9FWyLYFkdUwf8EpOyH+r/MAgo=; b=JfJFGw9cWLPbf5uHIIO3j8FD3Vx0gZhgLiUz2Bb0S+7QVUG5JfDcpwlJIpmGBZwL7Jjg mZ8IPohUNlOriFnZrkAYyNnQjeZ6JUVsA1aEoCgKqt9udsaxvxK5bFce9Y+6yehN5ZFXC mefIIZ8b+QipUN57wqGbdpPmC3jEZAmcIRB2A5R/oX3fPj12B4M/iot7mDJS2C5KLXDet su4vMjfi50BWKlYVOM0CpPcVkAM1eR7qxcXXmLNI/5SHy0/qqgSM64GkDhv8IuT4PzBCY LqRCCCVeRzs9ig7uh/PpgHvnSGCsRj3F9pYnq4wqncoteERPv1SvNuXGj5AnV9TaKSg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=dxpNYZVX; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A36F6075A6B for ; Mon, 2 Nov 2026 16:00:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=dxpNYZVX Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB6191F00A17; Mon, 2 Nov 2026 16:00:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793635259; bh=z5QV5L82RZqkGo+Xib9FWyLYFkdUwf8EpOyH+r/MAgo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dxpNYZVXFwTg3hLOetLtIPkToDdxt20OIH95SmHIWXk87RGsjxBRTiTtfvaXr+dRB 5rZWe9iD/P+ckHcsv54YbopzM3/b1bdUDSJxNLvrjQB+HKz7H5GkqVyVOWc8uXp8yi EoHjKgmQ4r4EpITAHyehb70TLFbNyiRjJVjZTDWt2W2JVb75uxbIgX2h+yF/+Q6zKz iQXYd39rk4112lkHswYJmKhf56LDP9K271/Ak6NQOC0tgy1q/lYIm99bwOUDjuqiln 46+zKOqSjAHxGhKid06PxTR1oYed9ldY8QsagopSsCeXXrJA25l4vzZxhtCp5HWSck tZHTP09deXsBA== From: Tzung-Bi Shih To: Philipp Zabel Cc: Bartosz Golaszewski , linux-kernel@vger.kernel.org, tzungbi@kernel.org Subject: [PATCH 2/2] reset: Fix circular locking dependency in reset_controller_unregister() Date: Mon, 2 Nov 2026 23:58:40 +0800 Message-ID: <20261102155840.20376-3-tzungbi@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261102155840.20376-1-tzungbi@kernel.org> References: <20261102155840.20376-1-tzungbi@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit reset_control_acquire() and reset_control_put_internal() acquire `rcdev->lock` inside the `rstc->srcu` read-side critical section (`rstc->srcu` -> `rcdev->lock`). However, reset_controller_unregister() holds `rcdev->lock` while calling synchronize_srcu(&rstc->srcu) (`rcdev->lock` -> `rstc->srcu`), causing a lockdep circular locking dependency warning and a potential ABBA deadlock. Run synchronize_srcu() outside `rcdev->lock`. Fixes: 44a0acb2caca ("reset: protect struct reset_controller_dev with its own mutex") Signed-off-by: Tzung-Bi Shih --- Test: With "[PATCH v2] reset: Add KUnit test cases"[1] applied: $ ./tools/testing/kunit/kunit.py run \ --kconfig_add CONFIG_RESET_CONTROLLER=y \ --kconfig_add CONFIG_RESET_KUNIT_TEST=y \ --kconfig_add CONFIG_PROVE_LOCKING=y \ --kconfig_add CONFIG_DEBUG_KERNEL=y \ --kconfig_add CONFIG_KASAN=y \ --arch=x86_64 \ --raw_output=all \ reset_test [1] https://lore.kernel.org/all/20261102155207.19252-1-tzungbi@kernel.org --- drivers/reset/core.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/reset/core.c b/drivers/reset/core.c index 1f6d7ef48a67..a36a4d6ff445 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -179,6 +179,7 @@ static void reset_controller_remove(struct reset_controller_dev *rcdev, void reset_controller_unregister(struct reset_controller_dev *rcdev) { struct reset_control *rstc, *pos; + LIST_HEAD(reset_control_head); scoped_guard(mutex, &reset_list_mutex) list_del(&rcdev->list); @@ -195,12 +196,22 @@ void reset_controller_unregister(struct reset_controller_dev *rcdev) list_for_each_entry_safe(rstc, pos, &rcdev->reset_control_head, list) { kref_get(&rstc->refcnt); rcu_assign_pointer(rstc->rcdev, NULL); - synchronize_srcu(&rstc->srcu); reset_controller_remove(rcdev, rstc); - reset_control_put_internal(rstc); + list_add(&rstc->list, &reset_control_head); } } + /* + * Run synchronize_srcu() outside rcdev->lock to avoid a circular + * locking dependency with paths that acquire rcdev->lock inside + * the rstc->srcu read-side critical section. + */ + list_for_each_entry_safe(rstc, pos, &reset_control_head, list) { + list_del(&rstc->list); + synchronize_srcu(&rstc->srcu); + reset_control_put_internal(rstc); + } + mutex_destroy(&rcdev->lock); } EXPORT_SYMBOL_GPL(reset_controller_unregister); -- 2.53.0