[v4] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag

[PATCH v4] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag

Posted by Chen Lin 2 years, 3 months ago

When rx_flag == MTK_RX_FLAGS_HWLRO,
rx_data_len = MTK_MAX_LRO_RX_LENGTH(4096 * 3) > PAGE_SIZE.
netdev_alloc_frag is for alloction of page fragment only.
Reference to other drivers and Documentation/vm/page_frags.rst

Branch to use __get_free_pages when ring->frag_size > PAGE_SIZE.

Signed-off-by: Chen Lin <chen45464546@163.com>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c |   21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index b3b3c07..3da162e 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -899,6 +899,17 @@ static bool mtk_rx_get_desc(struct mtk_eth *eth, struct mtk_rx_dma_v2 *rxd,
 	return true;
 }
 
+static inline void *mtk_max_lro_buf_alloc(gfp_t gfp_mask)
+{
+	void *data;
+
+	data = (void *)__get_free_pages(gfp_mask |
+			  __GFP_COMP | __GFP_NOWARN,
+			  get_order(mtk_max_frag_size(MTK_MAX_LRO_RX_LENGTH)));
+
+	return data;
+}
+
 /* the qdma core needs scratch memory to be setup */
 static int mtk_init_fq_dma(struct mtk_eth *eth)
 {
@@ -1467,7 +1478,10 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 			goto release_desc;
 
 		/* alloc new buffer */
-		new_data = napi_alloc_frag(ring->frag_size);
+		if (ring->frag_size <= PAGE_SIZE)
+			new_data = napi_alloc_frag(ring->frag_size);
+		else
+			new_data = mtk_max_lro_buf_alloc(GFP_ATOMIC);
 		if (unlikely(!new_data)) {
 			netdev->stats.rx_dropped++;
 			goto release_desc;
@@ -1914,7 +1928,10 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 		return -ENOMEM;
 
 	for (i = 0; i < rx_dma_size; i++) {
-		ring->data[i] = netdev_alloc_frag(ring->frag_size);
+		if (ring->frag_size <= PAGE_SIZE)
+			ring->data[i] = netdev_alloc_frag(ring->frag_size);
+		else
+			ring->data[i] = mtk_max_lro_buf_alloc(GFP_KERNEL);
 		if (!ring->data[i])
 			return -ENOMEM;
 	}
-- 
1.7.9.5

Re: [PATCH v4] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag

Posted by Jakub Kicinski 2 years, 3 months ago

On Tue,  7 Jun 2022 07:39:11 +0800 Chen Lin wrote:
> +static inline void *mtk_max_lro_buf_alloc(gfp_t gfp_mask)

No need for inline, compiler will inline this anyway.

> +{
> +	void *data;

unsigned long data; then you can move the cast from the long line to
the return statement, saving us from the strange indentation.

> +	data = (void *)__get_free_pages(gfp_mask |
> +			  __GFP_COMP | __GFP_NOWARN,
> +			  get_order(mtk_max_frag_size(MTK_MAX_LRO_RX_LENGTH)));
> +
> +	return data;
> +}

Re:Re: [PATCH v4] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag

Posted by Chen Lin 2 years, 3 months ago

At 2022-06-08 07:14:13, "Jakub Kicinski" <kuba@kernel.org> wrote:
>On Tue,  7 Jun 2022 07:39:11 +0800 Chen Lin wrote:
>> +static inline void *mtk_max_lro_buf_alloc(gfp_t gfp_mask)
>
>No need for inline, compiler will inline this anyway.
>
>> +{
>> +	void *data;
>
>unsigned long data; then you can move the cast from the long line to
>the return statement, saving us from the strange indentation.
>
>> +	data = (void *)__get_free_pages(gfp_mask |
>> +			  __GFP_COMP | __GFP_NOWARN,
>> +			  get_order(mtk_max_frag_size(MTK_MAX_LRO_RX_LENGTH)));
>> +
>> +	return data;
>> +}

I'll do it like below :
+static void *mtk_max_lro_buf_alloc(gfp_t gfp_mask)
+{
+       unsigned long data;
+       unsigned int size = mtk_max_frag_size(MTK_MAX_LRO_RX_LENGTH);
+
+       data = __get_free_pages(gfp_mask | __GFP_COMP | __GFP_NOWARN,
+                               get_order(size));
+
+       return (void *)data;
+}

Through analysis of the ASM code from objdump, I confirmed that 
the inline is not necessary. Thanks for your tips.

Also, I confirmed that create a new local variable 'size'
will not affect the generation of a constant 'order' parameter at compile time.


ASM code of calling 'mtk_max_lro_buf_alloc':

'mtk_max_lro_buf_alloc' inlined and 'order'(w1) is a constant 0x2
0000000000004530 <mtk_napi_rx>:
...
4a98:       52854400        mov     w0, #0x2a20                     // #10784
4a9c:       52800041        mov     w1, #0x2                        // #2
4aa0:       72a00080        movk    w0, #0x4, lsl #16
4aa4:       94000000        bl      0 <__get_free_pages>
4aa8:       f90033e0        str     x0, [sp, #96]

0000000000000730 <mtk_rx_alloc>:
...
7fc:       2a1703e0        mov     w0, w23
800:       52800041        mov     w1, #0x2                        // #2
804:       7140047f        cmp     w3, #0x1, lsl #12
808:       54fffe49        b.ls    7d0 <mtk_rx_alloc+0xa0>  // b.plast
80c:       94000000        bl      0 <__get_free_pages>

The compiler is smart.

[PATCH v5] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag

Posted by Chen Lin 2 years, 3 months ago

When rx_flag == MTK_RX_FLAGS_HWLRO,
rx_data_len = MTK_MAX_LRO_RX_LENGTH(4096 * 3) > PAGE_SIZE.
netdev_alloc_frag is for alloction of page fragment only.
Reference to other drivers and Documentation/vm/page_frags.rst

Branch to use __get_free_pages when ring->frag_size > PAGE_SIZE.

Signed-off-by: Chen Lin <chen45464546@163.com>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c |   21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index b3b3c07..aba0d84 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -899,6 +899,17 @@ static bool mtk_rx_get_desc(struct mtk_eth *eth, struct mtk_rx_dma_v2 *rxd,
 	return true;
 }
 
+static void *mtk_max_lro_buf_alloc(gfp_t gfp_mask)
+{
+	unsigned long data;
+	unsigned int size = mtk_max_frag_size(MTK_MAX_LRO_RX_LENGTH);
+
+	data = __get_free_pages(gfp_mask | __GFP_COMP | __GFP_NOWARN,
+				get_order(size));
+
+	return (void *)data;
+}
+
 /* the qdma core needs scratch memory to be setup */
 static int mtk_init_fq_dma(struct mtk_eth *eth)
 {
@@ -1467,7 +1478,10 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 			goto release_desc;
 
 		/* alloc new buffer */
-		new_data = napi_alloc_frag(ring->frag_size);
+		if (ring->frag_size <= PAGE_SIZE)
+			new_data = napi_alloc_frag(ring->frag_size);
+		else
+			new_data = mtk_max_lro_buf_alloc(GFP_ATOMIC);
 		if (unlikely(!new_data)) {
 			netdev->stats.rx_dropped++;
 			goto release_desc;
@@ -1914,7 +1928,10 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 		return -ENOMEM;
 
 	for (i = 0; i < rx_dma_size; i++) {
-		ring->data[i] = netdev_alloc_frag(ring->frag_size);
+		if (ring->frag_size <= PAGE_SIZE)
+			ring->data[i] = netdev_alloc_frag(ring->frag_size);
+		else
+			ring->data[i] = mtk_max_lro_buf_alloc(GFP_KERNEL);
 		if (!ring->data[i])
 			return -ENOMEM;
 	}
-- 
1.7.9.5

Re: [PATCH v5] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag

Posted by patchwork-bot+netdevbpf@kernel.org 2 years, 3 months ago

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Wed,  8 Jun 2022 20:46:53 +0800 you wrote:
> When rx_flag == MTK_RX_FLAGS_HWLRO,
> rx_data_len = MTK_MAX_LRO_RX_LENGTH(4096 * 3) > PAGE_SIZE.
> netdev_alloc_frag is for alloction of page fragment only.
> Reference to other drivers and Documentation/vm/page_frags.rst
> 
> Branch to use __get_free_pages when ring->frag_size > PAGE_SIZE.
> 
> [...]

Here is the summary with links:
  - [v5] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag
    https://git.kernel.org/netdev/net/c/2f2c0d2919a1

You are awesome, thank you!
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