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=1793844118; b=gdxOtFa/v6Fwg9jv+3Epr40uUhZDshmm4OHREOQTgA2Uogfld39J33aQLMqb5dNULXgj WUuIxSOm65DiblVVWYUNis8ZaWsjQm9/tQeG9gjfy7uQx/MlfKmYKUcpiBlrC2GPPt8kc tsVmusgYuZzinE/zpMW7IXfVU875lbDFnAAms+J3IQTotPYtn1nMgLQQUXPvOw8Y6wmRv wTn3QzV9qH/XcieSacucsTYNgKTYtYw6gyFbE0uCy/zbXmrggevgPb5I+BhpOM5PHa0gJ d+EI+T5QfZN7doWQ85AaTZ2t1UpqXjbUOkNpOyMY15PqibnM2Gf2u6xrIGr0pCuu7Lw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793844118; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=ELcgfz6ChtNwW6CDjkwXPF2lAOc+SLg0gHzUsi9Fyqw=; b=hfCL1NQw4co+ByvUMkbBDEdhwLHqjWo87KDmA5GW+iu3wUlR+wUr/Nrlm4IkHnEvGQm2 VdtzRIF1zHGsVVJ16e3Px5gHiriyqoozfy7YOhIVexooQXeD8eQ9CtQaQlxL42JwISW4p 6TFMpwvuB/HQ+oTFy0Un3VeepwHkYxJa14s3KFdQn4tJ2TE0ne7moiaiasfi+bJa0dHbG 2GtI11Q73WhcSZT3xFxAU22jNx8Mx7PyrD3gcYY0pjAEOHvU63e0SKFPpi94RlXYCEb8f D5sUexYvY8HcN+9eNjv4UgHenYEG/r6Pms6M7BSAw4xpLGDFuNM1JVixVJq2+/eqinQ== 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=Qer+Jy3K; 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 24AEE606CC09 for ; Thu, 5 Nov 2026 02:01:57 +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=Qer+Jy3K Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F7361F000C1; Thu, 5 Nov 2026 02:01:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793844117; bh=ELcgfz6ChtNwW6CDjkwXPF2lAOc+SLg0gHzUsi9Fyqw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Qer+Jy3KORxPBJgDrzsVtsIfgjHZayB8yRGCHNTThfE+zz8vVMi0XgnzHLT0j4Iia Tl1wALkFo00sDWDWvUtilY/pegZgEa9OcGvZO7OOt/R6j7OLNLAqnEaxOIyRMzcvPv zLn2wjcDtmTQF7wTAxtVlNadr2I9+CIeok9BicOJ6AqWvgODUlJ0SBg4p5zJp/Xqd+ NlnzUgO0ArufdO4oE2Frts+0QVkJDgtqCcsNTOuGqWmserrSHxGeGv5CySuWDiyL0T RCR9UKgn5iOOUjiEW1IWX/wPvHtRRS4ihxQj+7ibGH9fRKu416M53bbGO5sDjgJzUY 7sBCpofY2trEg== From: Sasha Levin To: stable@vger.kernel.org Cc: Sean Young , Hans Verkuil , Sasha Levin Subject: [PATCH 6.1.y] media: rc: Fix ABBA deadlock by making locks more fine grained Date: Wed, 4 Nov 2026 21:01:56 -0500 Message-ID: <20261105020044.1081944-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110414-outsource-laxative-3178@gregkh> References: <2026110414-outsource-laxative-3178@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: Retained ir_raw_event_free(dev) before releasing ir_raw_handler_lock to preserve the existing cleanup layout. ] 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 16e33d7eaaa2d..d1c551aec63ca 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 */ @@ -288,13 +289,6 @@ 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 @@ -632,15 +626,18 @@ 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; } @@ -664,8 +661,10 @@ 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)) @@ -681,6 +680,8 @@ 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); } /* @@ -703,15 +704,24 @@ 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