This is a note to let you know that I've just added the patch titled net: thunderx: use spin_lock_bh in nicvf_set_rx_mode_task() to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-thunderx-use-spin_lock_bh-in-nicvf_set_rx_mode_task.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Mon 10 Aug 2020 02:07:44 PM CEST From: Xin Long <lucien.xin@xxxxxxxxx> Date: Tue, 4 Aug 2020 15:02:30 +0800 Subject: net: thunderx: use spin_lock_bh in nicvf_set_rx_mode_task() From: Xin Long <lucien.xin@xxxxxxxxx> [ Upstream commit bab9693a9a8c6dd19f670408ec1e78e12a320682 ] A dead lock was triggered on thunderx driver: CPU0 CPU1 ---- ---- [01] lock(&(&nic->rx_mode_wq_lock)->rlock); [11] lock(&(&mc->mca_lock)->rlock); [12] lock(&(&nic->rx_mode_wq_lock)->rlock); [02] <Interrupt> lock(&(&mc->mca_lock)->rlock); The path for each is: [01] worker_thread() -> process_one_work() -> nicvf_set_rx_mode_task() [02] mld_ifc_timer_expire() [11] ipv6_add_dev() -> ipv6_dev_mc_inc() -> igmp6_group_added() -> [12] dev_mc_add() -> __dev_set_rx_mode() -> nicvf_set_rx_mode() To fix it, it needs to disable bh on [1], so that the timer on [2] wouldn't be triggered until rx_mode_wq_lock is released. So change to use spin_lock_bh() instead of spin_lock(). Thanks to Paolo for helping with this. v1->v2: - post to netdev. Reported-by: Rafael P. <rparrazo@xxxxxxxxxx> Tested-by: Dean Nelson <dnelson@xxxxxxxxxx> Fixes: 469998c861fa ("net: thunderx: prevent concurrent data re-writing by nicvf_set_rx_mode") Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/ethernet/cavium/thunder/nicvf_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c @@ -2047,11 +2047,11 @@ static void nicvf_set_rx_mode_task(struc /* Save message data locally to prevent them from * being overwritten by next ndo_set_rx_mode call(). */ - spin_lock(&nic->rx_mode_wq_lock); + spin_lock_bh(&nic->rx_mode_wq_lock); mode = vf_work->mode; mc = vf_work->mc; vf_work->mc = NULL; - spin_unlock(&nic->rx_mode_wq_lock); + spin_unlock_bh(&nic->rx_mode_wq_lock); __nicvf_set_rx_mode_task(mode, mc, nic); } Patches currently in stable-queue which might be from lucien.xin@xxxxxxxxx are queue-5.4/net-thunderx-use-spin_lock_bh-in-nicvf_set_rx_mode_task.patch