mlxsw: spectrum_router: Use gen_pool for RIF index allocation

Currently, each router interface (RIF) consumes one entry in the RIFs
table and there are no alignment constraints. This is going to change in
subsequent patches where some RIFs will consume two table entries and
their indexes will need to be aligned to the allocation size (even).

Prepare for this change by converting the RIF index allocation to use
gen_pool with the 'gen_pool_first_fit_order_align' algorithm.

No Kconfig changes necessary as mlxsw already selects
'GENERIC_ALLOCATOR'.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Amit Cohen <amcohen@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -18,6 +18,7 @@
 #include <linux/jhash.h>
 #include <linux/net_namespace.h>
 #include <linux/mutex.h>
+#include <linux/genalloc.h>
 #include <net/netevent.h>
 #include <net/neighbour.h>
 #include <net/arp.h>
@@ -7828,16 +7829,18 @@ mlxsw_sp_dev_rif_type(const struct mlxsw_sp *mlxsw_sp,
 
 static int mlxsw_sp_rif_index_alloc(struct mlxsw_sp *mlxsw_sp, u16 *p_rif_index)
 {
-	int i;
+	*p_rif_index = gen_pool_alloc(mlxsw_sp->router->rifs_table, 1);
+	if (*p_rif_index == 0)
+		return -ENOBUFS;
+	*p_rif_index -= MLXSW_SP_ROUTER_GENALLOC_OFFSET;
 
-	for (i = 0; i < MLXSW_CORE_RES_GET(mlxsw_sp->core, MAX_RIFS); i++) {
-		if (!mlxsw_sp->router->rifs[i]) {
-			*p_rif_index = i;
-			return 0;
-		}
-	}
+	return 0;
+}
 
-	return -ENOBUFS;
+static void mlxsw_sp_rif_index_free(struct mlxsw_sp *mlxsw_sp, u16 rif_index)
+{
+	gen_pool_free(mlxsw_sp->router->rifs_table,
+		      MLXSW_SP_ROUTER_GENALLOC_OFFSET + rif_index, 1);
 }
 
 static struct mlxsw_sp_rif *mlxsw_sp_rif_alloc(size_t rif_size, u16 rif_index,
@@ -8162,6 +8165,7 @@ err_fid_get:
 	dev_put(rif->dev);
 	kfree(rif);
 err_rif_alloc:
+	mlxsw_sp_rif_index_free(mlxsw_sp, rif_index);
 err_rif_index_alloc:
 	vr->rif_count--;
 	mlxsw_sp_vr_put(mlxsw_sp, vr);
@@ -8173,6 +8177,7 @@ static void mlxsw_sp_rif_destroy(struct mlxsw_sp_rif *rif)
 	const struct mlxsw_sp_rif_ops *ops = rif->ops;
 	struct mlxsw_sp *mlxsw_sp = rif->mlxsw_sp;
 	struct mlxsw_sp_fid *fid = rif->fid;
+	u16 rif_index = rif->rif_index;
 	struct mlxsw_sp_vr *vr;
 	int i;
 
@@ -8198,6 +8203,7 @@ static void mlxsw_sp_rif_destroy(struct mlxsw_sp_rif *rif)
 	mlxsw_sp->router->rifs[rif->rif_index] = NULL;
 	dev_put(rif->dev);
 	kfree(rif);
+	mlxsw_sp_rif_index_free(mlxsw_sp, rif_index);
 	vr->rif_count--;
 	mlxsw_sp_vr_put(mlxsw_sp, vr);
 }
@@ -9781,8 +9787,10 @@ mlxsw_sp_ul_rif_create(struct mlxsw_sp *mlxsw_sp, struct mlxsw_sp_vr *vr,
 	}
 
 	ul_rif = mlxsw_sp_rif_alloc(sizeof(*ul_rif), rif_index, vr->id, NULL);
-	if (!ul_rif)
-		return ERR_PTR(-ENOMEM);
+	if (!ul_rif) {
+		err = -ENOMEM;
+		goto err_rif_alloc;
+	}
 
 	mlxsw_sp->router->rifs[rif_index] = ul_rif;
 	ul_rif->mlxsw_sp = mlxsw_sp;
@@ -9796,17 +9804,21 @@ mlxsw_sp_ul_rif_create(struct mlxsw_sp *mlxsw_sp, struct mlxsw_sp_vr *vr,
 ul_rif_op_err:
 	mlxsw_sp->router->rifs[rif_index] = NULL;
 	kfree(ul_rif);
+err_rif_alloc:
+	mlxsw_sp_rif_index_free(mlxsw_sp, rif_index);
 	return ERR_PTR(err);
 }
 
 static void mlxsw_sp_ul_rif_destroy(struct mlxsw_sp_rif *ul_rif)
 {
 	struct mlxsw_sp *mlxsw_sp = ul_rif->mlxsw_sp;
+	u16 rif_index = ul_rif->rif_index;
 
 	atomic_dec(&mlxsw_sp->router->rifs_count);
 	mlxsw_sp_rif_ipip_lb_ul_rif_op(ul_rif, false);
 	mlxsw_sp->router->rifs[ul_rif->rif_index] = NULL;
 	kfree(ul_rif);
+	mlxsw_sp_rif_index_free(mlxsw_sp, rif_index);
 }
 
 static struct mlxsw_sp_rif *
@@ -9940,11 +9952,43 @@ static const struct mlxsw_sp_rif_ops *mlxsw_sp2_rif_ops_arr[] = {
 	[MLXSW_SP_RIF_TYPE_IPIP_LB]	= &mlxsw_sp2_rif_ipip_lb_ops,
 };
 
+static int mlxsw_sp_rifs_table_init(struct mlxsw_sp *mlxsw_sp)
+{
+	struct gen_pool *rifs_table;
+	int err;
+
+	rifs_table = gen_pool_create(0, -1);
+	if (!rifs_table)
+		return -ENOMEM;
+
+	gen_pool_set_algo(rifs_table, gen_pool_first_fit_order_align,
+			  NULL);
+
+	err = gen_pool_add(rifs_table, MLXSW_SP_ROUTER_GENALLOC_OFFSET,
+			   MLXSW_CORE_RES_GET(mlxsw_sp->core, MAX_RIFS), -1);
+	if (err)
+		goto err_gen_pool_add;
+
+	mlxsw_sp->router->rifs_table = rifs_table;
+
+	return 0;
+
+err_gen_pool_add:
+	gen_pool_destroy(rifs_table);
+	return err;
+}
+
+static void mlxsw_sp_rifs_table_fini(struct mlxsw_sp *mlxsw_sp)
+{
+	gen_pool_destroy(mlxsw_sp->router->rifs_table);
+}
+
 static int mlxsw_sp_rifs_init(struct mlxsw_sp *mlxsw_sp)
 {
 	u64 max_rifs = MLXSW_CORE_RES_GET(mlxsw_sp->core, MAX_RIFS);
 	struct devlink *devlink = priv_to_devlink(mlxsw_sp->core);
 	struct mlxsw_core *core = mlxsw_sp->core;
+	int err;
 
 	if (!MLXSW_CORE_RES_VALID(core, MAX_RIF_MAC_PROFILES))
 		return -EIO;
@@ -9957,6 +10001,10 @@ static int mlxsw_sp_rifs_init(struct mlxsw_sp *mlxsw_sp)
 	if (!mlxsw_sp->router->rifs)
 		return -ENOMEM;
 
+	err = mlxsw_sp_rifs_table_init(mlxsw_sp);
+	if (err)
+		goto err_rifs_table_init;
+
 	idr_init(&mlxsw_sp->router->rif_mac_profiles_idr);
 	atomic_set(&mlxsw_sp->router->rif_mac_profiles_count, 0);
 	atomic_set(&mlxsw_sp->router->rifs_count, 0);
@@ -9970,6 +10018,10 @@ static int mlxsw_sp_rifs_init(struct mlxsw_sp *mlxsw_sp)
 				       mlxsw_sp);
 
 	return 0;
+
+err_rifs_table_init:
+	kfree(mlxsw_sp->router->rifs);
+	return err;
 }
 
 static void mlxsw_sp_rifs_fini(struct mlxsw_sp *mlxsw_sp)
@@ -9986,6 +10038,7 @@ static void mlxsw_sp_rifs_fini(struct mlxsw_sp *mlxsw_sp)
 					 MLXSW_SP_RESOURCE_RIF_MAC_PROFILES);
 	WARN_ON(!idr_is_empty(&mlxsw_sp->router->rif_mac_profiles_idr));
 	idr_destroy(&mlxsw_sp->router->rif_mac_profiles_idr);
+	mlxsw_sp_rifs_table_fini(mlxsw_sp);
 	kfree(mlxsw_sp->router->rifs);
 }
 

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.h

@@ -15,8 +15,12 @@ struct mlxsw_sp_router_nve_decap {
 	u8 valid:1;
 };
 
+/* gen_pool_alloc() returns 0 when allocation fails, so use an offset */
+#define MLXSW_SP_ROUTER_GENALLOC_OFFSET 0x100
+
 struct mlxsw_sp_router {
 	struct mlxsw_sp *mlxsw_sp;
+	struct gen_pool *rifs_table;
 	struct mlxsw_sp_rif **rifs;
 	struct idr rif_mac_profiles_idr;
 	atomic_t rif_mac_profiles_count;