Commit bab9693a authored by Xin Long's avatar Xin Long Committed by David S. Miller

net: thunderx: use spin_lock_bh in nicvf_set_rx_mode_task()

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: default avatarRafael P. <rparrazo@redhat.com>
Tested-by: default avatarDean Nelson <dnelson@redhat.com>
Fixes: 469998c8 ("net: thunderx: prevent concurrent data re-writing by nicvf_set_rx_mode")
Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2ac24d6d
...@@ -2039,11 +2039,11 @@ static void nicvf_set_rx_mode_task(struct work_struct *work_arg) ...@@ -2039,11 +2039,11 @@ static void nicvf_set_rx_mode_task(struct work_struct *work_arg)
/* Save message data locally to prevent them from /* Save message data locally to prevent them from
* being overwritten by next ndo_set_rx_mode call(). * 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; mode = vf_work->mode;
mc = vf_work->mc; mc = vf_work->mc;
vf_work->mc = NULL; 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); __nicvf_set_rx_mode_task(mode, mc, nic);
} }
......
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