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 DFB9C3A9D91 for ; Mon, 9 Mar 2026 13:27:10 +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=1773062830; cv=none; b=m2zUQjDGaMJQNTB5Yv1eCKQhyYhS4FFA0mzUP90dO8dYykrqTaWeYof4W8y1TEPYzhoKqoZLVqaDBs7/RgyYL+3Y8rb+l8vr6TzUBhuLLhWhkc9A3W8CgJPSI3japH2TJ/8yiZ7CaCPaTwTJ8Zy4Psj4Edy/aMxtIWjp3+PqTnY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773062830; c=relaxed/simple; bh=C9IBZOHx1/beluy9Uac4ILxq++WMc7GEHahA3gWb2K8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HX9BjYPEpdOlA7PS+sOpRYvOBE51LyQRK17ctgIrEcIf5MN2HBkNDAiwSR+c5oUFOmQJo6cbIHte3sR0YAoq/S2K2NbnfdyeMfjXabcsFesGoAgPOqBTdozrm7YClEBUGShMII14cjCt5WRnNdwb6qrnkF4xJQXuDkcpkVS8FT8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pLCIOQqt; 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="pLCIOQqt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3D8CC4CEF7; Mon, 9 Mar 2026 13:27:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773062830; bh=C9IBZOHx1/beluy9Uac4ILxq++WMc7GEHahA3gWb2K8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pLCIOQqtm5qE5nvI3pARPTiu8/pg6gN3yS1bpI20kS2hi7n9o4J6mtKnSkrNt4iGF SQYutF79VGyAWnsCl+ESqTOoGEd4fVgOO9jFiiuHKITiPGaHrkQBYlk+1xF+yMuJXf 93U3F6TeZMSaHOwQmFeV6d5m9cDrQaMsLlFJVnlKixgeCEUKFCCMuQhZ0zWTpV+07G SCX86tQt8fsbEyeer6WHmZwOQOXkNlsAXtF8rrmufduNFvXrmED0eoUIqX5AJFmL04 KmZz7xTLtrihi2h5kySCiWlG56a561pFanWEld7OuLBfIeaZUsJXQZLH7Jee+K1Tm3 sRkbsC/O48kNA== From: Sasha Levin To: stable@vger.kernel.org Cc: Andrew Lunn , Shiji Yang , Paolo Abeni , Sasha Levin Subject: [PATCH 6.6.y] net: phy: register phy led_triggers during probe to avoid AB-BA deadlock Date: Mon, 9 Mar 2026 09:27:08 -0400 Message-ID: <20260309132708.943315-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2026030934-barley-student-214b@gregkh> References: <2026030934-barley-student-214b@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 [ adapted condition to preserve existing `!phy_driver_is_genphy_10g(phydev)` guard ] Signed-off-by: Sasha Levin --- drivers/net/phy/phy_device.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index 3dd59376a89e8..1d073947dd4c2 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -1582,8 +1582,6 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, goto error; phy_resume(phydev); - if (!phydev->is_on_sfp_module) - phy_led_triggers_register(phydev); /** * If the external phy used by current mac interface is managed by @@ -1856,9 +1854,6 @@ void phy_detach(struct phy_device *phydev) phydev->phy_link_change = NULL; phydev->phylink = NULL; - if (!phydev->is_on_sfp_module) - phy_led_triggers_unregister(phydev); - if (phydev->mdio.dev.driver) module_put(phydev->mdio.dev.driver->owner); @@ -3402,17 +3397,28 @@ static int phy_probe(struct device *dev) /* Set the state to READY by default */ phydev->state = PHY_READY; + /* Register the PHY LED triggers */ + if (!phydev->is_on_sfp_module) + phy_led_triggers_register(phydev); + /* Get the LEDs from the device tree, and instantiate standard * LEDs for them. */ if (IS_ENABLED(CONFIG_PHYLIB_LEDS) && !phy_driver_is_genphy(phydev) && - !phy_driver_is_genphy_10g(phydev)) + !phy_driver_is_genphy_10g(phydev)) { err = of_phy_leds(phydev); + if (err) + goto out; + } + + return 0; out: + if (!phydev->is_on_sfp_module) + phy_led_triggers_unregister(phydev); + /* Re-assert the reset signal on error */ - if (err) - phy_device_reset(phydev, 1); + phy_device_reset(phydev, 1); return err; } @@ -3427,6 +3433,9 @@ static int phy_remove(struct device *dev) !phy_driver_is_genphy_10g(phydev)) phy_leds_unregister(phydev); + if (!phydev->is_on_sfp_module) + phy_led_triggers_unregister(phydev); + phydev->state = PHY_DOWN; sfp_bus_del_upstream(phydev->sfp_bus); -- 2.51.0