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=1794061646; b=lnFm26ODxjLev0CsJ2zadqfA9KY1uhOYbmPjZQWNpDgH0XNkZZv+Sp8ID1y6R/Vah9mM Jv9Gd9yB2jmCWcw7s2VtHHD/ibk5gxoZ214MWp9r7LvZLi1/qSKuadeKV6qWiODal45Yq 8jA3m5NysCXwWuAppLcYJEuP8g+aKd9ZnTJMTaEe6qOY4ESlH8502C/qgZ86B72iv1U1z 5xLKZ9uRNacFePm+dUrlVI+CY+l1pg/dwdncMiAtVJYEsvu5NxF3Q3ARwJ8v6eo7vNp9+ S95MtOL0HtqKXaioyWcEJqlNe/u6jy3TPztg76azbYlHrvkfKjI30y9t2YC08OKWxaQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061646; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=p7LWHCVllI/2kZny41sUPPnlLMtcJlnO3e4YZYQC4cU=; b=nXX/rSyY0tGhoTAfw7wfqN3wEitGpL1zuYywYRU1+ZFUoJJX8Ja+RpxOiUVXbp+9nNZx hngw6e+lr9MGtCVmfHzfZnllp8vQxXflfIbI6buUC5uAAd56NkYn0rEm+Ul8rzhV4ma1V PB4BX921P5R3o6p6bc+fhC0bF1h58OPmLNGxsUiGfZvJEiHMjlEpIxsAGWmED36utBOP7 zhkoqe6i4Y+l/9VenIkR3Laf65X+ssn/QE41uzY7/awCvpv0FmUWLSvLipsfSwY0Hg77b jRCWgLL0u8KwmcUs+xCNtu4EAPEU0dzDP/PztnfCvTBspsNxCRziQ2Drqc+DJ0ZwgGg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=njACfFR8; 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 E5C47606A32C; Sat, 7 Nov 2026 14:27:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=njACfFR8 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8E27A1F0089F; Sat, 7 Nov 2026 14:27:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061645; bh=p7LWHCVllI/2kZny41sUPPnlLMtcJlnO3e4YZYQC4cU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=njACfFR8LticpRnEu0bYVQTjYOT46akKofOHDNCGpljCdWbCooo4DD2pVXcr8cBiI jf4H7CLKbJ7N5H2CoZ1zs509lx0dnGoYOkN+Vdhq4HKeNXOTPiBd5/sDc/RmuhcYfn 1bbT6oQsAGIwhjHjCtSz1xgn9uufEotJsajk5s4o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sean Young , Hans Verkuil Subject: [PATCH 6.12 0668/1536] media: rc: Fix ABBA deadlock by making locks more fine grained Date: Sat, 7 Nov 2026 08:44:44 -0500 Message-ID: <20261107135016.250727621@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sean Young commit c6d68866ad8aa1e957a3e5a6ede971148f1e3d59 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- drivers/media/rc/rc-ir-raw.c | 39 ++++++++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 15 deletions(-) --- 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 */ @@ -288,13 +289,6 @@ static int change_protocol(struct rc_dev 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 @@ -632,15 +626,18 @@ int ir_raw_event_register(struct rc_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; } @@ -673,16 +670,19 @@ void ir_raw_event_unregister(struct rc_d 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)) handler->raw_unregister(dev); lirc_bpf_free(dev); - mutex_unlock(&ir_raw_handler_lock); + + mutex_unlock(&ir_raw_client_lock); } /* @@ -705,15 +705,24 @@ void ir_raw_handler_unregister(struct ir 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);