mlxsw: spectrum: Protect counter pool with a lock

The counter pool is a shared resource. It is used by both the ACL code
to allocate counters for actions and by the routing code to allocate
counters for adjacency entries (for example).

Currently, all allocations are protected by RTNL, but this is going to
change with the removal of RTNL from the routing code.

Therefore, protect counter allocations with a spin lock.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -3,6 +3,7 @@
 
 #include <linux/kernel.h>
 #include <linux/bitops.h>
+#include <linux/spinlock.h>
 
 #include "spectrum_cnt.h"
 
@@ -18,6 +19,7 @@ struct mlxsw_sp_counter_sub_pool {
 struct mlxsw_sp_counter_pool {
 	unsigned int pool_size;
 	unsigned long *usage; /* Usage bitmap */
+	spinlock_t counter_pool_lock; /* Protects counter pool allocations */
 	struct mlxsw_sp_counter_sub_pool *sub_pools;
 };
 
@@ -87,6 +89,7 @@ int mlxsw_sp_counter_pool_init(struct mlxsw_sp *mlxsw_sp)
 	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
 	if (!pool)
 		return -ENOMEM;
+	spin_lock_init(&pool->counter_pool_lock);
 
 	pool->pool_size = MLXSW_CORE_RES_GET(mlxsw_sp->core, COUNTER_POOL_SIZE);
 	map_size = BITS_TO_LONGS(pool->pool_size) * sizeof(unsigned long);
@@ -139,25 +142,35 @@ int mlxsw_sp_counter_alloc(struct mlxsw_sp *mlxsw_sp,
 	struct mlxsw_sp_counter_sub_pool *sub_pool;
 	unsigned int entry_index;
 	unsigned int stop_index;
-	int i;
+	int i, err;
 
 	sub_pool = &mlxsw_sp_counter_sub_pools[sub_pool_id];
 	stop_index = sub_pool->base_index + sub_pool->size;
 	entry_index = sub_pool->base_index;
 
+	spin_lock(&pool->counter_pool_lock);
 	entry_index = find_next_zero_bit(pool->usage, stop_index, entry_index);
-	if (entry_index == stop_index)
-		return -ENOBUFS;
+	if (entry_index == stop_index) {
+		err = -ENOBUFS;
+		goto err_alloc;
+	}
 	/* The sub-pools can contain non-integer number of entries
 	 * so we must check for overflow
 	 */
-	if (entry_index + sub_pool->entry_size > stop_index)
-		return -ENOBUFS;
+	if (entry_index + sub_pool->entry_size > stop_index) {
+		err = -ENOBUFS;
+		goto err_alloc;
+	}
 	for (i = 0; i < sub_pool->entry_size; i++)
 		__set_bit(entry_index + i, pool->usage);
+	spin_unlock(&pool->counter_pool_lock);
 
 	*p_counter_index = entry_index;
 	return 0;
+
+err_alloc:
+	spin_unlock(&pool->counter_pool_lock);
+	return err;
 }
 
 void mlxsw_sp_counter_free(struct mlxsw_sp *mlxsw_sp,
@@ -171,6 +184,8 @@ void mlxsw_sp_counter_free(struct mlxsw_sp *mlxsw_sp,
 	if (WARN_ON(counter_index >= pool->pool_size))
 		return;
 	sub_pool = &mlxsw_sp_counter_sub_pools[sub_pool_id];
+	spin_lock(&pool->counter_pool_lock);
 	for (i = 0; i < sub_pool->entry_size; i++)
 		__clear_bit(counter_index + i, pool->usage);
+	spin_unlock(&pool->counter_pool_lock);
 }