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

Since commit 71ce391dfb ("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: 71ce391dfb ("net: mvpp2: enable proper per-CPU TX buffers unmapping")
Reported-by: Raphael G <raphael.glon@corp.ovh.com>
Cc: Raphael G <raphael.glon@corp.ovh.com>
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Thomas Petazzoni 2016-12-21 11:28:49 +01:00 committed by David S. Miller
parent f217bfde24
commit 8354491c9d
1 changed files with 30 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
drivers/net/ethernet/marvell/mvpp2.c
View File

@ -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),
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)
txq_pcpu->buffs = kmalloc(txq_pcpu->size *
sizeof(struct mvpp2_txq_pcpu_buf),
GFP_KERNEL);
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)