net/mlx4_core: Avoid delays during VF driver device shutdown

Some Hypervisors detach VFs from VMs by instantly causing an FLR event
to be generated for a VF.

In the mlx4 case, this will cause that VF's comm channel to be disabled
before the VM has an opportunity to invoke the VF device's "shutdown"
method.

For such Hypervisors, there is a race condition between the VF's
shutdown method and its internal-error detection/reset thread.

The internal-error detection/reset thread (which runs every 5 seconds) also
detects a disabled comm channel. If the internal-error detection/reset
flow wins the race, we still get delays (while that flow tries repeatedly
to detect comm-channel recovery).

The cited commit fixed the command timeout problem when the
internal-error detection/reset flow loses the race.

This commit avoids the unneeded delays when the internal-error
detection/reset flow wins.

Fixes: d585df1c5ccf ("net/mlx4_core: Avoid command timeouts during VF driver device shutdown")
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Reported-by: Simon Xiao <sixiao@microsoft.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx4/cmd.c b/drivers/net/ethernet/mellanox/mlx4/cmd.c
index e8c105164931f31ff0cf5ed12acef455d0010eda..0e0fa70305659521ed50d1cf1bc40fd38aa3ad04 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx4/cmd.c
@@ -2305,6 +2305,17 @@ static int sync_toggles(struct mlx4_dev *dev)
                rd_toggle = swab32(readl(&priv->mfunc.comm->slave_read));
                if (wr_toggle == 0xffffffff || rd_toggle == 0xffffffff) {
                        /* PCI might be offline */
+
+                       /* If device removal has been requested,
+                        * do not continue retrying.
+                        */
+                       if (dev->persist->interface_state &
+                           MLX4_INTERFACE_STATE_NOWAIT) {
+                               mlx4_warn(dev,
+                                         "communication channel is offline\n");
+                               return -EIO;
+                       }
+
                        msleep(100);
                        wr_toggle = swab32(readl(&priv->mfunc.comm->
                                           slave_write));

diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
index 21377c315083b686d8db25033583dd020d7e50a6..703205475524d689cd2762f2d2ce3abfd2b6ebcb 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/main.c
@@ -1940,6 +1940,14 @@ static int mlx4_comm_check_offline(struct mlx4_dev *dev)
                               (u32)(1 << COMM_CHAN_OFFLINE_OFFSET));
                if (!offline_bit)
                        return 0;
+
+               /* If device removal has been requested,
+                * do not continue retrying.
+                */
+               if (dev->persist->interface_state &
+                   MLX4_INTERFACE_STATE_NOWAIT)
+                       break;
+
                /* There are cases as part of AER/Reset flow that PF needs
                 * around 100 msec to load. We therefore sleep for 100 msec
                 * to allow other tasks to make use of that CPU during this
@@ -3955,6 +3963,9 @@ static void mlx4_remove_one(struct pci_dev *pdev)
        struct devlink *devlink = priv_to_devlink(priv);
        int active_vfs = 0;
 
+       if (mlx4_is_slave(dev))
+               persist->interface_state |= MLX4_INTERFACE_STATE_NOWAIT;
+
        mutex_lock(&persist->interface_state_mutex);
        persist->interface_state |= MLX4_INTERFACE_STATE_DELETION;
        mutex_unlock(&persist->interface_state_mutex);

diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index 7e66e4f62858f395cd000226e9580785b03a4cf1..1beb1ec2fbdf339b34affc69508a5f5462b409b0 100644 (file)
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h
@@ -476,6 +476,7 @@ enum {
 enum {
        MLX4_INTERFACE_STATE_UP         = 1 << 0,
        MLX4_INTERFACE_STATE_DELETION   = 1 << 1,
+       MLX4_INTERFACE_STATE_NOWAIT     = 1 << 2,
 };
 
 #define MSTR_SM_CHANGE_MASK (MLX4_EQ_PORT_INFO_MSTR_SM_SL_CHANGE_MASK | \