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 695BA3A9D88 for ; Mon, 9 Mar 2026 13:50:35 +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=1773064235; cv=none; b=EIwKIISLFqLu1ubtEt2a51pX/iKPn1HmPQxbH7UiqKjKzJpUylmgOF97n+tmZQALWK/MoO8mzggau/9tC7ttuuqoXgvr7+8O0GDdeodEYABR08WQ012gvHExhgBOcrXAFxTDVUBwR2dJqlcNZangJDCSZiA2YC97dy8VPIxOmiU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773064235; c=relaxed/simple; bh=6DPNIKkUx6jgsUBojTU0nztwf4kiPTykUOuIvbCx5Ik=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kwrbe92dri+pd/7xNPuNoTlxaDYj2N6eAHbDaDhg3mmKbxT0kRBYX/7AefA3XSvTriEWSdrfjyigIPOZ15yU4XM7GmzY9kUR7CX547AdoyqNTe/CzUwKlujSivZss8FWa8vBBxK5EvZB4gwAVfxNh9vsY0R/vpqIHA6KIhB8sQ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H2aRN4Fj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="H2aRN4Fj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A0AE0C4CEF7; Mon, 9 Mar 2026 13:50:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773064235; bh=6DPNIKkUx6jgsUBojTU0nztwf4kiPTykUOuIvbCx5Ik=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H2aRN4FjrLuufBgKDehZepQQPgWHBbudawlP5gig/7RPZ9s3m8DI8YtScZjgAcyg1 lzT97anU4bVxT55wuRxEeYjE/BvvlwzvZsSoQTmHBR3rpr0hlDYLfVQJOFBFNjpdYC cP/1ur9+f3r5c1Rt0NZRH6tY8rdXttO1Lxb901kcJKZn4tvTu0IUnTlELjK9tYHtgn IfeNNdHPM+k/LztIgX/bQRI8jvSpij5KLoiKocKH9YNsbuIIB5YcZIJKQwEkoIBoTN m46bkyKF+TefHBuhmK9e5lOwxFJOi6xa9RUIpm7E2vnPtS7lnb0sdRjDGDo8jIVQB5 TPNZYvuB4IUdA== From: Sasha Levin To: stable@vger.kernel.org Cc: Andrew Lunn , Shiji Yang , Paolo Abeni , Sasha Levin Subject: [PATCH 6.1.y] net: phy: register phy led_triggers during probe to avoid AB-BA deadlock Date: Mon, 9 Mar 2026 09:50:33 -0400 Message-ID: <20260309135033.1025776-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2026030935-operation-badass-b1bc@gregkh> References: <2026030935-operation-badass-b1bc@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Andrew Lunn [ Upstream commit c8dbdc6e380e7e96a51706db3e4b7870d8a9402d ] There is an AB-BA deadlock when both LEDS_TRIGGER_NETDEV and LED_TRIGGER_PHY are enabled: [ 1362.049207] [<8054e4b8>] led_trigger_register+0x5c/0x1fc <-- Trying to get lock "triggers_list_lock" via down_write(&triggers_list_lock); [ 1362.054536] [<80662830>] phy_led_triggers_register+0xd0/0x234 [ 1362.060329] [<8065e200>] phy_attach_direct+0x33c/0x40c [ 1362.065489] [<80651fc4>] phylink_fwnode_phy_connect+0x15c/0x23c [ 1362.071480] [<8066ee18>] mtk_open+0x7c/0xba0 [ 1362.075849] [<806d714c>] __dev_open+0x280/0x2b0 [ 1362.080384] [<806d7668>] __dev_change_flags+0x244/0x24c [ 1362.085598] [<806d7698>] dev_change_flags+0x28/0x78 [ 1362.090528] [<807150e4>] dev_ioctl+0x4c0/0x654 <-- Hold lock "rtnl_mutex" by calling rtnl_lock(); [ 1362.094985] [<80694360>] sock_ioctl+0x2f4/0x4e0 [ 1362.099567] [<802e9c4c>] sys_ioctl+0x32c/0xd8c [ 1362.104022] [<80014504>] syscall_common+0x34/0x58 Here LED_TRIGGER_PHY is registering LED triggers during phy_attach while holding RTNL and then taking triggers_list_lock. [ 1362.191101] [<806c2640>] register_netdevice_notifier+0x60/0x168 <-- Trying to get lock "rtnl_mutex" via rtnl_lock(); [ 1362.197073] [<805504ac>] netdev_trig_activate+0x194/0x1e4 [ 1362.202490] [<8054e28c>] led_trigger_set+0x1d4/0x360 <-- Hold lock "triggers_list_lock" by down_read(&triggers_list_lock); [ 1362.207511] [<8054eb38>] led_trigger_write+0xd8/0x14c [ 1362.212566] [<80381d98>] sysfs_kf_bin_write+0x80/0xbc [ 1362.217688] [<8037fcd8>] kernfs_fop_write_iter+0x17c/0x28c [ 1362.223174] [<802cbd70>] vfs_write+0x21c/0x3c4 [ 1362.227712] [<802cc0c4>] ksys_write+0x78/0x12c [ 1362.232164] [<80014504>] syscall_common+0x34/0x58 Here LEDS_TRIGGER_NETDEV is being enabled on an LED. It first takes triggers_list_lock and then RTNL. A classical AB-BA deadlock. phy_led_triggers_registers() does not require the RTNL, it does not make any calls into the network stack which require protection. There is also no requirement the PHY has been attached to a MAC, the triggers only make use of phydev state. This allows the call to phy_led_triggers_registers() to be placed elsewhere. PHY probe() and release() don't hold RTNL, so solving the AB-BA deadlock. Reported-by: Shiji Yang Closes: https://lore.kernel.org/all/OS7PR01MB13602B128BA1AD3FA38B6D1FFBC69A@OS7PR01MB13602.jpnprd01.prod.outlook.com/ Fixes: 06f502f57d0d ("leds: trigger: Introduce a NETDEV trigger") Cc: stable@vger.kernel.org Signed-off-by: Andrew Lunn Tested-by: Shiji Yang Link: https://patch.msgid.link/20260222152601.1978655-1-andrew@lunn.ch Signed-off-by: Paolo Abeni [ dropped `is_on_sfp_module` guards and `CONFIG_PHYLIB_LEDS`/`of_phy_leds` logic ] Signed-off-by: Sasha Levin --- drivers/net/phy/phy_device.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index f25b0d338ca8d..11839dca8f56e 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -1510,7 +1510,6 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, goto error; phy_resume(phydev); - phy_led_triggers_register(phydev); return err; @@ -1767,8 +1766,6 @@ void phy_detach(struct phy_device *phydev) } phydev->phylink = NULL; - phy_led_triggers_unregister(phydev); - if (phydev->mdio.dev.driver) module_put(phydev->mdio.dev.driver->owner); @@ -3109,10 +3106,14 @@ static int phy_probe(struct device *dev) /* Set the state to READY by default */ phydev->state = PHY_READY; + /* Register the PHY LED triggers */ + phy_led_triggers_register(phydev); + + return 0; + out: /* Re-assert the reset signal on error */ - if (err) - phy_device_reset(phydev, 1); + phy_device_reset(phydev, 1); return err; } @@ -3123,6 +3124,8 @@ static int phy_remove(struct device *dev) cancel_delayed_work_sync(&phydev->state_queue); + phy_led_triggers_unregister(phydev); + phydev->state = PHY_DOWN; sfp_bus_del_upstream(phydev->sfp_bus); -- 2.51.0