From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CBF603C199C; Thu, 15 Jan 2026 17:32:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768498371; cv=none; b=g1gpQFr0CAmKUHUbLQHbz3yv7Qga98bAUyHghZFIjARuklRL8Dl+MBVDivIZ4CfDIa15xxi1MX4m06pOvwM7bUK5XrcPfnwY5rEwP//9vBoK5vmU9zMq6abtj8/zaVrqWHI+rEVEaIjwUOmVeUOmlRfHZsVGLkJtE4er734d5w4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768498371; c=relaxed/simple; bh=EhGUXMMZHl9T4DzkR3GpbyAjvS/MQD1VEYaeMz/ca/M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rsxyjOUAsR0oD6pPopDeEtIMUNKw4HD/xRMyzy5LTQQobQ7UqvlLu00USGbNfss4NWVCPgjANbxr43LPwuV2etppu9ZzA8BZnVn58Z+qs1efiJi3HvHMV2VxlXB+KWddOOIh5W5Nq9qa2JPDqJMDVEZB2i0Rn+bX9X37GOnY/mc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XHAmTpOg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="XHAmTpOg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59908C116D0; Thu, 15 Jan 2026 17:32:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768498371; bh=EhGUXMMZHl9T4DzkR3GpbyAjvS/MQD1VEYaeMz/ca/M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XHAmTpOgob4ewpG4lqyhnJgccIEOflRcYUWuOjAEs5jtrGEtBz+rJapwOegeJwqkS OmqnTW+jqLbC6ONB9zuRDvD4hW8O/MNRNo/5cl232UTCCEUnlWNL82yK85n8Re+VzF YGCpzrvai7lLk7YT8dCuq1XLOharrOFTk6Joyb20= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kevin Hao , Xiaolei Wang , Paolo Abeni Subject: [PATCH 5.15 408/554] net: macb: Relocate mog_init_rings() callback from macb_mac_link_up() to macb_open() Date: Thu, 15 Jan 2026 17:47:54 +0100 Message-ID: <20260115164301.000400985@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164246.225995385@linuxfoundation.org> References: <20260115164246.225995385@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiaolei Wang commit 99537d5c476cada9cf75aef9fa75579a31faadb9 upstream. In the non-RT kernel, local_bh_disable() merely disables preemption, whereas it maps to an actual spin lock in the RT kernel. Consequently, when attempting to refill RX buffers via netdev_alloc_skb() in macb_mac_link_up(), a deadlock scenario arises as follows: WARNING: possible circular locking dependency detected 6.18.0-08691-g2061f18ad76e #39 Not tainted ------------------------------------------------------ kworker/0:0/8 is trying to acquire lock: ffff00080369bbe0 (&bp->lock){+.+.}-{3:3}, at: macb_start_xmit+0x808/0xb7c but task is already holding lock: ffff000803698e58 (&queue->tx_ptr_lock){+...}-{3:3}, at: macb_start_xmit +0x148/0xb7c which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&queue->tx_ptr_lock){+...}-{3:3}: rt_spin_lock+0x50/0x1f0 macb_start_xmit+0x148/0xb7c dev_hard_start_xmit+0x94/0x284 sch_direct_xmit+0x8c/0x37c __dev_queue_xmit+0x708/0x1120 neigh_resolve_output+0x148/0x28c ip6_finish_output2+0x2c0/0xb2c __ip6_finish_output+0x114/0x308 ip6_output+0xc4/0x4a4 mld_sendpack+0x220/0x68c mld_ifc_work+0x2a8/0x4f4 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 -> #2 (_xmit_ETHER#2){+...}-{3:3}: rt_spin_lock+0x50/0x1f0 sch_direct_xmit+0x11c/0x37c __dev_queue_xmit+0x708/0x1120 neigh_resolve_output+0x148/0x28c ip6_finish_output2+0x2c0/0xb2c __ip6_finish_output+0x114/0x308 ip6_output+0xc4/0x4a4 mld_sendpack+0x220/0x68c mld_ifc_work+0x2a8/0x4f4 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 -> #1 ((softirq_ctrl.lock)){+.+.}-{3:3}: lock_release+0x250/0x348 __local_bh_enable_ip+0x7c/0x240 __netdev_alloc_skb+0x1b4/0x1d8 gem_rx_refill+0xdc/0x240 gem_init_rings+0xb4/0x108 macb_mac_link_up+0x9c/0x2b4 phylink_resolve+0x170/0x614 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 -> #0 (&bp->lock){+.+.}-{3:3}: __lock_acquire+0x15a8/0x2084 lock_acquire+0x1cc/0x350 rt_spin_lock+0x50/0x1f0 macb_start_xmit+0x808/0xb7c dev_hard_start_xmit+0x94/0x284 sch_direct_xmit+0x8c/0x37c __dev_queue_xmit+0x708/0x1120 neigh_resolve_output+0x148/0x28c ip6_finish_output2+0x2c0/0xb2c __ip6_finish_output+0x114/0x308 ip6_output+0xc4/0x4a4 mld_sendpack+0x220/0x68c mld_ifc_work+0x2a8/0x4f4 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 other info that might help us debug this: Chain exists of: &bp->lock --> _xmit_ETHER#2 --> &queue->tx_ptr_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&queue->tx_ptr_lock); lock(_xmit_ETHER#2); lock(&queue->tx_ptr_lock); lock(&bp->lock); *** DEADLOCK *** Call trace: show_stack+0x18/0x24 (C) dump_stack_lvl+0xa0/0xf0 dump_stack+0x18/0x24 print_circular_bug+0x28c/0x370 check_noncircular+0x198/0x1ac __lock_acquire+0x15a8/0x2084 lock_acquire+0x1cc/0x350 rt_spin_lock+0x50/0x1f0 macb_start_xmit+0x808/0xb7c dev_hard_start_xmit+0x94/0x284 sch_direct_xmit+0x8c/0x37c __dev_queue_xmit+0x708/0x1120 neigh_resolve_output+0x148/0x28c ip6_finish_output2+0x2c0/0xb2c __ip6_finish_output+0x114/0x308 ip6_output+0xc4/0x4a4 mld_sendpack+0x220/0x68c mld_ifc_work+0x2a8/0x4f4 process_one_work+0x20c/0x5f8 worker_thread+0x1b0/0x35c kthread+0x144/0x200 ret_from_fork+0x10/0x20 Notably, invoking the mog_init_rings() callback upon link establishment is unnecessary. Instead, we can exclusively call mog_init_rings() within the ndo_open() callback. This adjustment resolves the deadlock issue. Furthermore, since MACB_CAPS_MACB_IS_EMAC cases do not use mog_init_rings() when opening the network interface via at91ether_open(), moving mog_init_rings() to macb_open() also eliminates the MACB_CAPS_MACB_IS_EMAC check. Fixes: 633e98a711ac ("net: macb: use resolved link config in mac_link_up()") Cc: stable@vger.kernel.org Suggested-by: Kevin Hao Signed-off-by: Xiaolei Wang Link: https://patch.msgid.link/20251222015624.1994551-1-xiaolei.wang@windriver.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/cadence/macb_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -777,7 +777,6 @@ static void macb_mac_link_up(struct phyl /* Initialize rings & buffers as clearing MACB_BIT(TE) in link down * cleared the pipeline and control registers. */ - bp->macbgem_ops.mog_init_rings(bp); macb_init_buffers(bp); for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) @@ -2478,6 +2477,8 @@ static void gem_init_rings(struct macb * unsigned int q; int i; + bp->macbgem_ops.mog_init_rings(bp); + for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) { for (i = 0; i < bp->tx_ring_size; i++) { desc = macb_tx_desc(queue, i);