net/mlx5_core: Avoid usage command work entry after writing command doorbell

Avoid usage of command work entry in cmd_work_handler since it can be released
by mlx5_cmd_invoke before the work handler returns to running.
Signed-off-by: NIra Gusinsky <irenag@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: NEli Cohen <eli@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/cmd.c

@@ -515,10 +515,11 @@ static void cmd_work_handler(struct work_struct *work)
 	ent->ts1 = ktime_get_ns();
 
 	/* ring doorbell after the descriptor is valid */
+	mlx5_core_dbg(dev, "writing 0x%x to command doorbell\n", 1 << ent->idx);
 	wmb();
 	iowrite32be(1 << ent->idx, &dev->iseg->cmd_dbell);
-	mlx5_core_dbg(dev, "write 0x%x to command doorbell\n", 1 << ent->idx);
 	mmiowb();
+	/* if not in polling don't use ent after this point */
 	if (cmd->mode == CMD_MODE_POLLING) {
 		poll_timeout(ent);
 		/* make sure we read the descriptor after ownership is SW */