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 22C6D313298; Mon, 13 Apr 2026 16:49:48 +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=1776098988; cv=none; b=teM/8PZBXRe0sDUEue/vyBXSGWXSuMfxRAomM0xYzkK+kfJmdQg3WHjg/gaZtgRtLTVHBWuvMHI0+E7ogF/aC3uziGoszhuV97rvE/KJkQytu+tPUqeRjBRUsWSs+DyhZ4lx080WX9+qM+cvcHvdlenvHul+nW6bcaeL0z1OQc4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776098988; c=relaxed/simple; bh=zhkuVCv7M8JyLyfLx0L2Ge6dkhsIfciCeYQBTok5rCU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=st9vcDuYBM0ethRwOuPY3mlnYKiCkTGnF7KdW9byKkuihZZ2HSNZhDuets86VQKADuXPKyOQhJNG/Y7/yj9ANWAWw87QGWu6+X3uAE4YyTo8lwOvHX6SDO0sROtvphngaZLKqxcMlc4/mmfOtm3+O5W0n97IXS+AaqYnq0YFFlw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Frwzbt56; 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="Frwzbt56" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC43BC2BCAF; Mon, 13 Apr 2026 16:49:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776098988; bh=zhkuVCv7M8JyLyfLx0L2Ge6dkhsIfciCeYQBTok5rCU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Frwzbt56Nxol0I73Xl2lTiEI/3SgBTh/Q4LjCFigA/p22kGESyVRNFQmQjPo/q7be ieI01r18qNwa/VKBTQqMrJ4vmHNHDhewq6q7D4PtH7jucEAj8sa+CPra6vCbcS5GTl MBskTvqj+ug5nETlzmxEoiKfl8VbCQhvOkJiIFO4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Shiji Yang , Andrew Lunn , Paolo Abeni , Sasha Levin Subject: [PATCH 5.10 166/491] net: phy: register phy led_triggers during probe to avoid AB-BA deadlock Date: Mon, 13 Apr 2026 17:56:51 +0200 Message-ID: <20260413155825.255236682@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155819.042779211@linuxfoundation.org> References: <20260413155819.042779211@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- drivers/net/phy/phy_device.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -1412,7 +1412,6 @@ int phy_attach_direct(struct net_device return err; phy_resume(phydev); - phy_led_triggers_register(phydev); return err; @@ -1669,8 +1668,6 @@ void phy_detach(struct phy_device *phyde } phydev->phylink = NULL; - phy_led_triggers_unregister(phydev); - if (phydev->mdio.dev.driver) module_put(phydev->mdio.dev.driver->owner); @@ -2900,10 +2897,14 @@ 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; } @@ -2914,6 +2915,8 @@ 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);