mlx4_core: reserve UARs for userspace consumers

Do not allow a kernel consumer to allocate a UAR to serve for blue flame if the
number of available UARs gets below MLX4_NUM_RESERVED_UARS (currently 8). This
will allow userspace apps to open a device file and run things like
ibv_devinfo.

Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/net/mlx4/pd.c b/drivers/net/mlx4/pd.c
index 5210a0f31413..1286b886dcea 100644
--- a/drivers/net/mlx4/pd.c
+++ b/drivers/net/mlx4/pd.c
@@ -39,6 +39,10 @@
 #include "mlx4.h"
 #include "icm.h"
 
+enum {
+        MLX4_NUM_RESERVED_UARS = 8
+};
+
 int mlx4_pd_alloc(struct mlx4_dev *dev, u32 *pdn)
 {
         struct mlx4_priv *priv = mlx4_priv(dev);
@@ -104,6 +108,10 @@ int mlx4_bf_alloc(struct mlx4_dev *dev, struct mlx4_bf *bf)
         if (!list_empty(&priv->bf_list))
                 uar = list_entry(priv->bf_list.next, struct mlx4_uar, bf_list);
         else {
+                if (mlx4_bitmap_avail(&priv->uar_table.bitmap) < MLX4_NUM_RESERVED_UARS) {
+                        err = -ENOMEM;
+                        goto out;
+                }
                 uar = kmalloc(sizeof *uar, GFP_KERNEL);
                 if (!uar) {
                         err = -ENOMEM;