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i40e: Fix TSO with more than 8 frags per segment issue 

The hardware has some limitations the driver needs to adhere to,
that we found in extended testing.
  1) no more than 8 descriptors per packet on the wire
  2) no header can span more than 3 descriptors

If one of these events occurs, the hardware will generate an internal
error and freeze the Tx queue.

This patch linearizes the skb to avoid these situations.

Change-ID: I37dab7d3966e14895a9663ec4d0aaa8eb0d9e115
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Anjali Singhai 2015-02-21 06:42:35 +00:00 committed by Jeff Kirsher
parent b67a03357c
commit 71da61976e
4 changed files with 132 additions and 0 deletions
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65
drivers/net/ethernet/intel/i40e/i40e_txrx.c
View File

@ -2139,6 +2139,67 @@ static int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
return __i40e_maybe_stop_tx(tx_ring, size);
}
/**
* i40e_chk_linearize - Check if there are more than 8 fragments per packet
* @skb: send buffer
* @tx_flags: collected send information
* @hdr_len: size of the packet header
*
* Note: Our HW can't scatter-gather more than 8 fragments to build
* a packet on the wire and so we need to figure out the cases where we
* need to linearize the skb.
**/
static bool i40e_chk_linearize(struct sk_buff *skb, u32 tx_flags,
const u8 hdr_len)
{
struct skb_frag_struct *frag;
bool linearize = false;
unsigned int size = 0;
u16 num_frags;
u16 gso_segs;
num_frags = skb_shinfo(skb)->nr_frags;
gso_segs = skb_shinfo(skb)->gso_segs;
if (tx_flags & (I40E_TX_FLAGS_TSO | I40E_TX_FLAGS_FSO)) {
u16 j = 1;
if (num_frags < (I40E_MAX_BUFFER_TXD))
goto linearize_chk_done;
/* try the simple math, if we have too many frags per segment */
if (DIV_ROUND_UP((num_frags + gso_segs), gso_segs) >
I40E_MAX_BUFFER_TXD) {
linearize = true;
goto linearize_chk_done;
}
frag = &skb_shinfo(skb)->frags[0];
size = hdr_len;
/* we might still have more fragments per segment */
do {
size += skb_frag_size(frag);
frag++; j++;
if (j == I40E_MAX_BUFFER_TXD) {
if (size < skb_shinfo(skb)->gso_size) {
linearize = true;
break;
}
j = 1;
size -= skb_shinfo(skb)->gso_size;
if (size)
j++;
size += hdr_len;
}
num_frags--;
} while (num_frags);
} else {
if (num_frags >= I40E_MAX_BUFFER_TXD)
linearize = true;
}
linearize_chk_done:
return linearize;
}
/**
* i40e_tx_map - Build the Tx descriptor
* @tx_ring: ring to send buffer on
@ -2396,6 +2457,10 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
if (tsyn)
tx_flags |= I40E_TX_FLAGS_TSYN;
if (i40e_chk_linearize(skb, tx_flags, hdr_len))
if (skb_linearize(skb))
goto out_drop;
skb_tx_timestamp(skb);
/* always enable CRC insertion offload */

1
drivers/net/ethernet/intel/i40e/i40e_txrx.h
View File

@ -112,6 +112,7 @@ enum i40e_dyn_idx_t {
#define i40e_rx_desc i40e_32byte_rx_desc
#define I40E_MAX_BUFFER_TXD 8
#define I40E_MIN_TX_LEN 17
#define I40E_MAX_DATA_PER_TXD 8192

65
drivers/net/ethernet/intel/i40evf/i40e_txrx.c
View File

@ -1380,6 +1380,67 @@ static void i40e_create_tx_ctx(struct i40e_ring *tx_ring,
context_desc->type_cmd_tso_mss = cpu_to_le64(cd_type_cmd_tso_mss);
}
/**
* i40e_chk_linearize - Check if there are more than 8 fragments per packet
* @skb: send buffer
* @tx_flags: collected send information
* @hdr_len: size of the packet header
*
* Note: Our HW can't scatter-gather more than 8 fragments to build
* a packet on the wire and so we need to figure out the cases where we
* need to linearize the skb.
**/
static bool i40e_chk_linearize(struct sk_buff *skb, u32 tx_flags,
const u8 hdr_len)
{
struct skb_frag_struct *frag;
bool linearize = false;
unsigned int size = 0;
u16 num_frags;
u16 gso_segs;
num_frags = skb_shinfo(skb)->nr_frags;
gso_segs = skb_shinfo(skb)->gso_segs;
if (tx_flags & (I40E_TX_FLAGS_TSO | I40E_TX_FLAGS_FSO)) {
u16 j = 1;
if (num_frags < (I40E_MAX_BUFFER_TXD))
goto linearize_chk_done;
/* try the simple math, if we have too many frags per segment */
if (DIV_ROUND_UP((num_frags + gso_segs), gso_segs) >
I40E_MAX_BUFFER_TXD) {
linearize = true;
goto linearize_chk_done;
}
frag = &skb_shinfo(skb)->frags[0];
size = hdr_len;
/* we might still have more fragments per segment */
do {
size += skb_frag_size(frag);
frag++; j++;
if (j == I40E_MAX_BUFFER_TXD) {
if (size < skb_shinfo(skb)->gso_size) {
linearize = true;
break;
}
j = 1;
size -= skb_shinfo(skb)->gso_size;
if (size)
j++;
size += hdr_len;
}
num_frags--;
} while (num_frags);
} else {
if (num_frags >= I40E_MAX_BUFFER_TXD)
linearize = true;
}
linearize_chk_done:
return linearize;
}
/**
* i40e_tx_map - Build the Tx descriptor
* @tx_ring: ring to send buffer on
@ -1654,6 +1715,10 @@ static netdev_tx_t i40e_xmit_frame_ring(struct sk_buff *skb,
else if (tso)
tx_flags |= I40E_TX_FLAGS_TSO;
if (i40e_chk_linearize(skb, tx_flags, hdr_len))
if (skb_linearize(skb))
goto out_drop;
skb_tx_timestamp(skb);
/* always enable CRC insertion offload */

1
drivers/net/ethernet/intel/i40evf/i40e_txrx.h
View File

@ -112,6 +112,7 @@ enum i40e_dyn_idx_t {
#define i40e_rx_desc i40e_32byte_rx_desc
#define I40E_MAX_BUFFER_TXD 8
#define I40E_MIN_TX_LEN 17
#define I40E_MAX_DATA_PER_TXD 8192