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=1793847051; b=m/p/Zlz7+ffsCkpb3pCKEntz307pgDDk3ACjl8qL8MxbxmgrFsWxb5hPuSUWI6GuQkDJ LpJhaqs/XZukUZaHzBHoQv42nexc3q9OYL7+0mFl3gwmcUgtXqSyH0etf/bbtUbml0qYP dXxFAT679g6APQ6B3QFUkP2PNBLa7hrMyTPW68mccopOBBMV63x/1G7zqTnBpANzOnx62 RLLcehjCEKkjxseQBlRGUq1qRiEoY61/hTESSM6cbIirLJ2iZE5wBIm91mVuwQbkfj2ZA kWybWAhftd1oKMjB4o4a+tU0e70SQLy5O11MN6HXCdfhIn2fSQFdZpIb5HLDi0Dr8tw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793847051; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=hi1qcCC8EcE/ARzFL+mTdQwX6UWc+I7qO4OZRyVpPMA=; b=huFGU1YMYf5TZhn9jHCs72WRZ6UsEfRGvphGJlrRf25UyKNQUNsfjEcA19puoxGbutZZ zWRirsE0YD14xC9k7pKz2p+wA1VzAIZH55jLDrwHgG+LDZzQe7Qwsuna0ryATOwbEW6lb jZcO78rGDsSnrfvdPggftnfw6f3Nkq6TgVBxe9hxhwe5NpO0/YTS5/UNqZQcwwo+O4h6T QolCYOj3nPQDXDEfFM7jd0puMCwToB/5ns8UWeGmbJGnewqHBr5KuNYSpMSNluIP+e6Gj V2ZzWAIM/85vxOEC4cfREiufOPgPD221VmDZFQTbsxLWt2pGoyzV7gK34wfEGptruHQ== 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=akIGX9QE; 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 AA5EC606A326 for ; Thu, 5 Nov 2026 02:50:50 +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=akIGX9QE Received: by smtp.kernel.org (Postfix) with ESMTPSA id A37A41F00919; Thu, 5 Nov 2026 02:50:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793847050; bh=hi1qcCC8EcE/ARzFL+mTdQwX6UWc+I7qO4OZRyVpPMA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=akIGX9QE0/213DOiCBnK2qThOHUjCIRHBqoPyEioO5wqLPKEGAMMpcbsCIMlhQ26h K4eRD8gd75xNxA++Z4Seo36UcS0K/7GwW0AzM8ZW9EAsGs4aAUjlkNVedoK8XB2tfw 3KKRPQzB7kH2KxhHZ+AhGNbgAznbiSLZshU1OorP8P53SEgz3ApHzGjwerByuVkz5v PiSOqvlJPojsAvvT8NTMVR/dR/UNtvnmr5toI6hA5qM+DiBXr0D5tWb6oIZepnmT4/ h/Tx0jpstrCYtNe1VMWPiy3NbYjr1NOhJyL2GnZEIE9SfhtfBgr/fBU2VA7PMmoYUC cAM0vQFGDmZrw== From: Sasha Levin To: stable@vger.kernel.org Cc: Sean Young , Hans Verkuil , Sasha Levin Subject: [PATCH 5.15.y] media: rc: Fix ABBA deadlock by making locks more fine grained Date: Wed, 4 Nov 2026 21:50:48 -0500 Message-ID: <20261105025022.1173951-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110415-mocker-phony-91d4@gregkh> References: <2026110415-mocker-phony-91d4@gregkh> X-Mailing-List: stable@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 From: Sean Young [ Upstream commit c6d68866ad8aa1e957a3e5a6ede971148f1e3d59 ] The ir_raw_event_unregister() function takes the ir_raw_handler_lock first and then the rc_dev->lock. Other functions like change_protocol do this in the reverse order. This means that an ir decoder module unload and writing to the protocol sysfs file can cause a deadlock. ir_raw_handler_lock protects the client list, amongst other things. Split this out into a separate lock so we can ensure the locking order is always the same. Fixes: 93cffffc18f6 ("[media] media: rc: fix decoder module unloading") Signed-off-by: Sean Young Cc: stable@vger.kernel.org Acked-by: Hans Verkuil [ sashal: adjusted ir_raw_event_unregister() context for del_timer_sync() and the existing teardown sequence ] Signed-off-by: Sasha Levin --- drivers/media/rc/rc-ir-raw.c | 38 +++++++++++++++++++++++------------- 1 file changed, 24 insertions(+), 14 deletions(-) diff --git a/drivers/media/rc/rc-ir-raw.c b/drivers/media/rc/rc-ir-raw.c index c65bba4ec4739..304cc47e781ed 100644 --- a/drivers/media/rc/rc-ir-raw.c +++ b/drivers/media/rc/rc-ir-raw.c @@ -10,7 +10,8 @@ #include #include "rc-core-priv.h" -/* Used to keep track of IR raw clients, protected by ir_raw_handler_lock */ +/* Used to keep track of IR raw clients, protected by ir_raw_client_lock */ +static DEFINE_MUTEX(ir_raw_client_lock); static LIST_HEAD(ir_raw_client_list); /* Used to handle IR raw handler extensions */ @@ -290,13 +291,6 @@ static int change_protocol(struct rc_dev *dev, u64 *rc_proto) return 0; } -static void ir_raw_disable_protocols(struct rc_dev *dev, u64 protocols) -{ - mutex_lock(&dev->lock); - dev->enabled_protocols &= ~protocols; - mutex_unlock(&dev->lock); -} - /** * ir_raw_gen_manchester() - Encode data with Manchester (bi-phase) modulation. * @ev: Pointer to pointer to next free event. *@ev is incremented for @@ -634,15 +628,18 @@ int ir_raw_event_register(struct rc_dev *dev) { struct task_struct *thread; + /* Holding dev->lock could result in a dead-lock */ + lockdep_assert_not_held(&dev->lock); + thread = kthread_run(ir_raw_event_thread, dev->raw, "rc%u", dev->minor); if (IS_ERR(thread)) return PTR_ERR(thread); dev->raw->thread = thread; - mutex_lock(&ir_raw_handler_lock); + mutex_lock(&ir_raw_client_lock); list_add_tail(&dev->raw->list, &ir_raw_client_list); - mutex_unlock(&ir_raw_handler_lock); + mutex_unlock(&ir_raw_client_lock); return 0; } @@ -666,8 +663,10 @@ void ir_raw_event_unregister(struct rc_dev *dev) kthread_stop(dev->raw->thread); del_timer_sync(&dev->raw->edge_handle); - mutex_lock(&ir_raw_handler_lock); + mutex_lock(&ir_raw_client_lock); list_del(&dev->raw->list); + + mutex_lock(&ir_raw_handler_lock); list_for_each_entry(handler, &ir_raw_handler_list, list) if (handler->raw_unregister && (handler->protocols & dev->enabled_protocols)) @@ -683,6 +682,8 @@ void ir_raw_event_unregister(struct rc_dev *dev) * "device gone" is checked. */ mutex_unlock(&ir_raw_handler_lock); + + mutex_unlock(&ir_raw_client_lock); } /* @@ -705,15 +706,24 @@ void ir_raw_handler_unregister(struct ir_raw_handler *ir_raw_handler) struct ir_raw_event_ctrl *raw; u64 protocols = ir_raw_handler->protocols; + mutex_lock(&ir_raw_client_lock); + mutex_lock(&ir_raw_handler_lock); list_del(&ir_raw_handler->list); + atomic64_andnot(protocols, &available_protocols); + mutex_unlock(&ir_raw_handler_lock); + list_for_each_entry(raw, &ir_raw_client_list, list) { + mutex_lock(&raw->dev->lock); + mutex_lock(&ir_raw_handler_lock); if (ir_raw_handler->raw_unregister && (raw->dev->enabled_protocols & protocols)) ir_raw_handler->raw_unregister(raw->dev); - ir_raw_disable_protocols(raw->dev, protocols); + raw->dev->enabled_protocols &= ~protocols; + mutex_unlock(&ir_raw_handler_lock); + mutex_unlock(&raw->dev->lock); } - atomic64_andnot(protocols, &available_protocols); - mutex_unlock(&ir_raw_handler_lock); + + mutex_unlock(&ir_raw_client_lock); } EXPORT_SYMBOL(ir_raw_handler_unregister); -- 2.53.0