4.20-stable review patch. If anyone has any objections, please let me know.
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From: Jack Morgenstein jackm@dev.mellanox.co.il
[ Upstream commit c07d27927f2f2e96fcd27bb9fb330c9ea65612d0 ]
In procedures mlx4_cmd_use_events() and mlx4_cmd_use_polling(), we need to guarantee that there are no FW commands in progress on the comm channel (for VFs) or wrapped FW commands (on the PF) when SRIOV is active.
We do this by also taking the slave_cmd_mutex when SRIOV is active.
This is especially important when switching from event to polling, since we free the command-context array during the switch. If there are FW commands in progress (e.g., waiting for a completion event), the completion event handler will access freed memory.
Since the decision to use comm_wait or comm_poll is taken before grabbing the event_sem/poll_sem in mlx4_comm_cmd_wait/poll, we must take the slave_cmd_mutex as well (to guarantee that the decision to use events or polling and the call to the appropriate cmd function are atomic).
Fixes: a7e1f04905e5 ("net/mlx4_core: Fix deadlock when switching between polling and event fw commands") Signed-off-by: Jack Morgenstein jackm@dev.mellanox.co.il Signed-off-by: Tariq Toukan tariqt@mellanox.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/mellanox/mlx4/cmd.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/drivers/net/ethernet/mellanox/mlx4/cmd.c +++ b/drivers/net/ethernet/mellanox/mlx4/cmd.c @@ -2645,6 +2645,8 @@ int mlx4_cmd_use_events(struct mlx4_dev if (!priv->cmd.context) return -ENOMEM;
+ if (mlx4_is_mfunc(dev)) + mutex_lock(&priv->cmd.slave_cmd_mutex); down_write(&priv->cmd.switch_sem); for (i = 0; i < priv->cmd.max_cmds; ++i) { priv->cmd.context[i].token = i; @@ -2670,6 +2672,8 @@ int mlx4_cmd_use_events(struct mlx4_dev down(&priv->cmd.poll_sem); priv->cmd.use_events = 1; up_write(&priv->cmd.switch_sem); + if (mlx4_is_mfunc(dev)) + mutex_unlock(&priv->cmd.slave_cmd_mutex);
return err; } @@ -2682,6 +2686,8 @@ void mlx4_cmd_use_polling(struct mlx4_de struct mlx4_priv *priv = mlx4_priv(dev); int i;
+ if (mlx4_is_mfunc(dev)) + mutex_lock(&priv->cmd.slave_cmd_mutex); down_write(&priv->cmd.switch_sem); priv->cmd.use_events = 0;
@@ -2693,6 +2699,8 @@ void mlx4_cmd_use_polling(struct mlx4_de
up(&priv->cmd.poll_sem); up_write(&priv->cmd.switch_sem); + if (mlx4_is_mfunc(dev)) + mutex_unlock(&priv->cmd.slave_cmd_mutex); }
struct mlx4_cmd_mailbox *mlx4_alloc_cmd_mailbox(struct mlx4_dev *dev)