Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8354491c authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by David S. Miller
Browse files

net: mvpp2: fix dma unmapping of TX buffers for fragments 



Since commit 71ce391d ("net: mvpp2: enable proper per-CPU TX
buffers unmapping"), we are not correctly DMA unmapping TX buffers for
fragments.

Indeed, the mvpp2_txq_inc_put() function only stores in the
txq_cpu->tx_buffs[] array the physical address of the buffer to be
DMA-unmapped when skb != NULL. In addition, when DMA-unmapping, we use
skb_headlen(skb) to get the size to be unmapped. Both of this works fine
for TX descriptors that are associated directly to a SKB, but not the
ones that are used for fragments, with a NULL pointer as skb:

 - We have a NULL physical address when calling DMA unmap
 - skb_headlen(skb) crashes because skb is NULL

This causes random crashes when fragments are used.

To solve this problem, we need to:

 - Store the physical address of the buffer to be unmapped
   unconditionally, regardless of whether it is tied to a SKB or not.

 - Store the length of the buffer to be unmapped, which requires a new
   field.

Instead of adding a third array to store the length of the buffer to be
unmapped, and as suggested by David Miller, this commit refactors the
tx_buffs[] and tx_skb[] arrays of 'struct mvpp2_txq_pcpu' into a
separate structure 'mvpp2_txq_pcpu_buf', to which a 'size' field is
added. Therefore, instead of having three arrays to allocate/free, we
have a single one, which also improve data locality, reducing the
impact on the CPU cache.

Fixes: 71ce391d ("net: mvpp2: enable proper per-CPU TX buffers unmapping")
Reported-by: default avatarRaphael G <raphael.glon@corp.ovh.com>
Cc: Raphael G <raphael.glon@corp.ovh.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f217bfde

drivers/net/ethernet/marvell/mvpp2.c

+30 −29
Original line number Diff line number Diff line
@@ -770,6 +770,17 @@ struct mvpp2_rx_desc { 
	u32 reserved8;

};



struct mvpp2_txq_pcpu_buf {

	/* Transmitted SKB */

	struct sk_buff *skb;



	/* Physical address of transmitted buffer */

	dma_addr_t phys;



	/* Size transmitted */

	size_t size;

};



/* Per-CPU Tx queue control */

struct mvpp2_txq_pcpu {

	int cpu;
@@ -785,11 +796,8 @@ struct mvpp2_txq_pcpu { 
	/* Number of Tx DMA descriptors reserved for each CPU */

	int reserved_num;



	/* Array of transmitted skb */

	struct sk_buff **tx_skb;



	/* Array of transmitted buffers' physical addresses */

	dma_addr_t *tx_buffs;

	/* Infos about transmitted buffers */

	struct mvpp2_txq_pcpu_buf *buffs;



	/* Index of last TX DMA descriptor that was inserted */

	int txq_put_index;
@@ -979,10 +987,11 @@ static void mvpp2_txq_inc_put(struct mvpp2_txq_pcpu *txq_pcpu, 
			      struct sk_buff *skb,

			      struct mvpp2_tx_desc *tx_desc)

{

	txq_pcpu->tx_skb[txq_pcpu->txq_put_index] = skb;

	if (skb)

		txq_pcpu->tx_buffs[txq_pcpu->txq_put_index] =

							 tx_desc->buf_phys_addr;

	struct mvpp2_txq_pcpu_buf *tx_buf =

		txq_pcpu->buffs + txq_pcpu->txq_put_index;

	tx_buf->skb = skb;

	tx_buf->size = tx_desc->data_size;

	tx_buf->phys = tx_desc->buf_phys_addr;

	txq_pcpu->txq_put_index++;

	if (txq_pcpu->txq_put_index == txq_pcpu->size)

		txq_pcpu->txq_put_index = 0;
@@ -4401,17 +4410,16 @@ static void mvpp2_txq_bufs_free(struct mvpp2_port *port, 
	int i;



	for (i = 0; i < num; i++) {

		dma_addr_t buf_phys_addr =

				    txq_pcpu->tx_buffs[txq_pcpu->txq_get_index];

		struct sk_buff *skb = txq_pcpu->tx_skb[txq_pcpu->txq_get_index];

		struct mvpp2_txq_pcpu_buf *tx_buf =

			txq_pcpu->buffs + txq_pcpu->txq_get_index;



		mvpp2_txq_inc_get(txq_pcpu);



		dma_unmap_single(port->dev->dev.parent, buf_phys_addr,

				 skb_headlen(skb), DMA_TO_DEVICE);

		if (!skb)

		dma_unmap_single(port->dev->dev.parent, tx_buf->phys,

				 tx_buf->size, DMA_TO_DEVICE);

		if (!tx_buf->skb)

			continue;

		dev_kfree_skb_any(skb);

		dev_kfree_skb_any(tx_buf->skb);

	}

}
@@ -4651,15 +4659,10 @@ static int mvpp2_txq_init(struct mvpp2_port *port, 
	for_each_present_cpu(cpu) {

		txq_pcpu = per_cpu_ptr(txq->pcpu, cpu);

		txq_pcpu->size = txq->size;

		txq_pcpu->tx_skb = kmalloc(txq_pcpu->size *

					   sizeof(*txq_pcpu->tx_skb),

		txq_pcpu->buffs = kmalloc(txq_pcpu->size *

					  sizeof(struct mvpp2_txq_pcpu_buf),

					  GFP_KERNEL);

		if (!txq_pcpu->tx_skb)

			goto error;



		txq_pcpu->tx_buffs = kmalloc(txq_pcpu->size *

					     sizeof(dma_addr_t), GFP_KERNEL);

		if (!txq_pcpu->tx_buffs)

		if (!txq_pcpu->buffs)

			goto error;



		txq_pcpu->count = 0;
@@ -4673,8 +4676,7 @@ static int mvpp2_txq_init(struct mvpp2_port *port, 
error:

	for_each_present_cpu(cpu) {

		txq_pcpu = per_cpu_ptr(txq->pcpu, cpu);

		kfree(txq_pcpu->tx_skb);

		kfree(txq_pcpu->tx_buffs);

		kfree(txq_pcpu->buffs);

	}



	dma_free_coherent(port->dev->dev.parent,
@@ -4693,8 +4695,7 @@ static void mvpp2_txq_deinit(struct mvpp2_port *port, 


	for_each_present_cpu(cpu) {

		txq_pcpu = per_cpu_ptr(txq->pcpu, cpu);

		kfree(txq_pcpu->tx_skb);

		kfree(txq_pcpu->tx_buffs);

		kfree(txq_pcpu->buffs);

	}



	if (txq->descs)