RDMA/mlx5: Store the number of in_use cache mkeys instead of total_mrs

total_mrs is used only to calculate the number of mkeys currently in
use. To simplify things, replace it with a new member called "in_use" and
directly store the number of mkeys currently in use.

Link: https://lore.kernel.org/r/20220726071911.122765-4-michaelgur@nvidia.com
Signed-off-by: Aharon Landau <aharonl@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: aharonl-nvidia

drivers/infiniband/hw/mlx5/mlx5_ib.h

@@ -755,12 +755,10 @@ struct mlx5_cache_ent {
 	u8 fill_to_high_water:1;
 
 	/*
-	 * - total_mrs is stored mkeys plus all in use MRs that could be
-	 *   returned to the cache.
 	 * - limit is the low water mark for stored mkeys, 2* limit is the
 	 *   upper water mark.
 	 */
-	u32 total_mrs;
+	u32 in_use;
 	u32 limit;
 
 	/* Statistics */

drivers/infiniband/hw/mlx5/mr.c

@@ -268,7 +268,6 @@ static void create_mkey_callback(int status, struct mlx5_async_work *context)
 
 	xa_lock_irqsave(&ent->mkeys, flags);
 	push_to_reserved(ent, mr);
-	ent->total_mrs++;
 	/* If we are doing fill_to_high_water then keep going. */
 	queue_adjust_cache_locked(ent);
 	xa_unlock_irqrestore(&ent->mkeys, flags);
@@ -391,9 +390,6 @@ static struct mlx5_ib_mr *create_cache_mr(struct mlx5_cache_ent *ent)
 	init_waitqueue_head(&mr->mmkey.wait);
 	mr->mmkey.type = MLX5_MKEY_MR;
 	WRITE_ONCE(ent->dev->cache.last_add, jiffies);
-	xa_lock_irq(&ent->mkeys);
-	ent->total_mrs++;
-	xa_unlock_irq(&ent->mkeys);
 	kfree(in);
 	return mr;
 free_mr:
@@ -411,7 +407,6 @@ static void remove_cache_mr_locked(struct mlx5_cache_ent *ent)
 	if (!ent->stored)
 		return;
 	mr = pop_stored_mkey(ent);
-	ent->total_mrs--;
 	xa_unlock_irq(&ent->mkeys);
 	mlx5_core_destroy_mkey(ent->dev->mdev, mr->mmkey.key);
 	kfree(mr);
@@ -467,11 +462,11 @@ static ssize_t size_write(struct file *filp, const char __user *buf,
 	 * mkeys.
 	 */
 	xa_lock_irq(&ent->mkeys);
-	if (target < ent->total_mrs - ent->stored) {
+	if (target < ent->in_use) {
 		err = -EINVAL;
 		goto err_unlock;
 	}
-	target = target - (ent->total_mrs - ent->stored);
+	target = target - ent->in_use;
 	if (target < ent->limit || target > ent->limit*2) {
 		err = -EINVAL;
 		goto err_unlock;
@@ -495,7 +490,7 @@ static ssize_t size_read(struct file *filp, char __user *buf, size_t count,
 	char lbuf[20];
 	int err;
 
-	err = snprintf(lbuf, sizeof(lbuf), "%d\n", ent->total_mrs);
+	err = snprintf(lbuf, sizeof(lbuf), "%ld\n", ent->stored + ent->in_use);
 	if (err < 0)
 		return err;
 
@@ -689,13 +684,19 @@ struct mlx5_ib_mr *mlx5_mr_cache_alloc(struct mlx5_ib_dev *dev,
 		return ERR_PTR(-EOPNOTSUPP);
 
 	xa_lock_irq(&ent->mkeys);
+	ent->in_use++;
+
 	if (!ent->stored) {
 		queue_adjust_cache_locked(ent);
 		ent->miss++;
 		xa_unlock_irq(&ent->mkeys);
 		mr = create_cache_mr(ent);
-		if (IS_ERR(mr))
+		if (IS_ERR(mr)) {
+			xa_lock_irq(&ent->mkeys);
+			ent->in_use--;
+			xa_unlock_irq(&ent->mkeys);
 			return mr;
+		}
 	} else {
 		mr = pop_stored_mkey(ent);
 		queue_adjust_cache_locked(ent);
@@ -716,7 +717,6 @@ static void clean_keys(struct mlx5_ib_dev *dev, int c)
 	xa_lock_irq(&ent->mkeys);
 	while (ent->stored) {
 		mr = pop_stored_mkey(ent);
-		ent->total_mrs--;
 		xa_unlock_irq(&ent->mkeys);
 		mlx5_core_destroy_mkey(dev->mdev, mr->mmkey.key);
 		kfree(mr);
@@ -1642,13 +1642,13 @@ int mlx5_ib_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
 
 	/* Stop DMA */
 	if (mr->cache_ent) {
+		xa_lock_irq(&mr->cache_ent->mkeys);
+		mr->cache_ent->in_use--;
+		xa_unlock_irq(&mr->cache_ent->mkeys);
+
 		if (mlx5r_umr_revoke_mr(mr) ||
-		    push_mkey(mr->cache_ent, false, mr)) {
-			xa_lock_irq(&mr->cache_ent->mkeys);
-			mr->cache_ent->total_mrs--;
-			xa_unlock_irq(&mr->cache_ent->mkeys);
+		    push_mkey(mr->cache_ent, false, mr))
 			mr->cache_ent = NULL;
-		}
 	}
 	if (!mr->cache_ent) {
 		rc = destroy_mkey(to_mdev(mr->ibmr.device), mr);