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Date:   Fri, 15 May 2020 15:48:45 -0700
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>, kuba@...nel.org
Cc:     netdev@...r.kernel.org, Eran Ben Elisha <eranbe@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net-next 02/11] net/mlx5: Fix a bug of releasing wrong chunks on > 4K page size systems

From: Eran Ben Elisha <eranbe@...lanox.com>

On systems with page size larger than 4K, a fwp object has few 4K chunks.
Fix a bug in fwp free flow where the chunk address was dropped and
fwp->addr was used instead (first chunk address). This caused a wrong
update of fwp->bitmask which later can cause errors in re-alloc fwp
chunk flow.

In order to fix this it, re-factor the release flow:
- Free 4k: Releases a specific 4k chunk inside the fwp, defined by
  starting address.
- Free fwp: Unconditionally release the whole fwp and its resources.
Free addr will call free fwp if all chunks were released, in order to do
code sharing.

In addition, fix npages to count for all released chunks correctly.

Fixes: c6168161f693 ("net/mlx5: Add support for release all pages event")
Signed-off-by: Eran Ben Elisha <eranbe@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 .../ethernet/mellanox/mlx5/core/pagealloc.c   | 44 +++++++++----------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c
index 84f6356edbf8..5ddd18639a1e 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/pagealloc.c
@@ -188,35 +188,35 @@ static int alloc_4k(struct mlx5_core_dev *dev, u64 *addr, u16 func_id)
 
 #define MLX5_U64_4K_PAGE_MASK ((~(u64)0U) << PAGE_SHIFT)
 
-static void free_fwp(struct mlx5_core_dev *dev, struct fw_page *fwp)
+static void free_fwp(struct mlx5_core_dev *dev, struct fw_page *fwp,
+		     bool in_free_list)
 {
-	int n = (fwp->addr & ~MLX5_U64_4K_PAGE_MASK) >> MLX5_ADAPTER_PAGE_SHIFT;
-
-	fwp->free_count++;
-	set_bit(n, &fwp->bitmask);
-	if (fwp->free_count == MLX5_NUM_4K_IN_PAGE) {
-		rb_erase(&fwp->rb_node, &dev->priv.page_root);
-		if (fwp->free_count != 1)
-			list_del(&fwp->list);
-		dma_unmap_page(dev->device, fwp->addr & MLX5_U64_4K_PAGE_MASK,
-			       PAGE_SIZE, DMA_BIDIRECTIONAL);
-		__free_page(fwp->page);
-		kfree(fwp);
-	} else if (fwp->free_count == 1) {
-		list_add(&fwp->list, &dev->priv.free_list);
-	}
+	rb_erase(&fwp->rb_node, &dev->priv.page_root);
+	if (in_free_list)
+		list_del(&fwp->list);
+	dma_unmap_page(dev->device, fwp->addr & MLX5_U64_4K_PAGE_MASK,
+		       PAGE_SIZE, DMA_BIDIRECTIONAL);
+	__free_page(fwp->page);
+	kfree(fwp);
 }
 
-static void free_addr(struct mlx5_core_dev *dev, u64 addr)
+static void free_4k(struct mlx5_core_dev *dev, u64 addr)
 {
 	struct fw_page *fwp;
+	int n;
 
 	fwp = find_fw_page(dev, addr & MLX5_U64_4K_PAGE_MASK);
 	if (!fwp) {
 		mlx5_core_warn_rl(dev, "page not found\n");
 		return;
 	}
-	free_fwp(dev, fwp);
+	n = (addr & ~MLX5_U64_4K_PAGE_MASK) >> MLX5_ADAPTER_PAGE_SHIFT;
+	fwp->free_count++;
+	set_bit(n, &fwp->bitmask);
+	if (fwp->free_count == MLX5_NUM_4K_IN_PAGE)
+		free_fwp(dev, fwp, fwp->free_count != 1);
+	else if (fwp->free_count == 1)
+		list_add(&fwp->list, &dev->priv.free_list);
 }
 
 static int alloc_system_page(struct mlx5_core_dev *dev, u16 func_id)
@@ -340,7 +340,7 @@ static int give_pages(struct mlx5_core_dev *dev, u16 func_id, int npages,
 
 out_4k:
 	for (i--; i >= 0; i--)
-		free_addr(dev, MLX5_GET64(manage_pages_in, in, pas[i]));
+		free_4k(dev, MLX5_GET64(manage_pages_in, in, pas[i]));
 out_free:
 	kvfree(in);
 	if (notify_fail)
@@ -361,8 +361,8 @@ static void release_all_pages(struct mlx5_core_dev *dev, u32 func_id,
 		p = rb_next(p);
 		if (fwp->func_id != func_id)
 			continue;
-		free_fwp(dev, fwp);
-		npages++;
+		npages += (MLX5_NUM_4K_IN_PAGE - fwp->free_count);
+		free_fwp(dev, fwp, fwp->free_count);
 	}
 
 	dev->priv.fw_pages -= npages;
@@ -446,7 +446,7 @@ static int reclaim_pages(struct mlx5_core_dev *dev, u32 func_id, int npages,
 	}
 
 	for (i = 0; i < num_claimed; i++)
-		free_addr(dev, MLX5_GET64(manage_pages_out, out, pas[i]));
+		free_4k(dev, MLX5_GET64(manage_pages_out, out, pas[i]));
 
 	if (nclaimed)
 		*nclaimed = num_claimed;
-- 
2.25.4

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