forked from Minki/linux
i40e/i40evf: Limit TSO to 7 descriptors for payload instead of 8 per packet
This patch addresses a bug introduced based on my interpretation of the
XL710 datasheet. Specifically section 8.4.1 states that "A single transmit
packet may span up to 8 buffers (up to 8 data descriptors per packet
including both the header and payload buffers)." It then later goes on to
say that each segment for a TSO obeys the previous rule, however it then
refers to TSO header and the segment payload buffers.
I believe the actual limit for fragments with TSO and a skbuff that has
payload data in the header portion of the buffer is actually only 7
fragments as the skb->data portion counts as 2 buffers, one for the TSO
header, and one for a segment payload buffer.
Fixes: 2d37490b82
("i40e/i40evf: Rewrite logic for 8 descriptor per packet check")
Reported-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
parent
a6d37131c0
commit
3f3f7cb875
@ -2594,35 +2594,34 @@ int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
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}
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/**
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* __i40e_chk_linearize - Check if there are more than 8 fragments per packet
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* __i40e_chk_linearize - Check if there are more than 8 buffers per packet
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* @skb: send buffer
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*
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* Note: Our HW can't scatter-gather more than 8 fragments to build
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* a packet on the wire and so we need to figure out the cases where we
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* need to linearize the skb.
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* Note: Our HW can't DMA more than 8 buffers to build a packet on the wire
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* and so we need to figure out the cases where we need to linearize the skb.
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*
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* For TSO we need to count the TSO header and segment payload separately.
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* As such we need to check cases where we have 7 fragments or more as we
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* can potentially require 9 DMA transactions, 1 for the TSO header, 1 for
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* the segment payload in the first descriptor, and another 7 for the
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* fragments.
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**/
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bool __i40e_chk_linearize(struct sk_buff *skb)
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{
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const struct skb_frag_struct *frag, *stale;
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int gso_size, nr_frags, sum;
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int nr_frags, sum;
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/* check to see if TSO is enabled, if so we may get a repreive */
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gso_size = skb_shinfo(skb)->gso_size;
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if (unlikely(!gso_size))
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return true;
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/* no need to check if number of frags is less than 8 */
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/* no need to check if number of frags is less than 7 */
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nr_frags = skb_shinfo(skb)->nr_frags;
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if (nr_frags < I40E_MAX_BUFFER_TXD)
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if (nr_frags < (I40E_MAX_BUFFER_TXD - 1))
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return false;
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/* We need to walk through the list and validate that each group
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* of 6 fragments totals at least gso_size. However we don't need
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* to perform such validation on the first or last 6 since the first
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* 6 cannot inherit any data from a descriptor before them, and the
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* last 6 cannot inherit any data from a descriptor after them.
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* to perform such validation on the last 6 since the last 6 cannot
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* inherit any data from a descriptor after them.
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*/
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nr_frags -= I40E_MAX_BUFFER_TXD - 1;
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nr_frags -= I40E_MAX_BUFFER_TXD - 2;
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frag = &skb_shinfo(skb)->frags[0];
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/* Initialize size to the negative value of gso_size minus 1. We
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@ -2631,21 +2630,21 @@ bool __i40e_chk_linearize(struct sk_buff *skb)
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* descriptors for a single transmit as the header and previous
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* fragment are already consuming 2 descriptors.
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*/
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sum = 1 - gso_size;
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sum = 1 - skb_shinfo(skb)->gso_size;
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/* Add size of frags 1 through 5 to create our initial sum */
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(++frag);
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/* Add size of frags 0 through 4 to create our initial sum */
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sum += skb_frag_size(frag++);
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sum += skb_frag_size(frag++);
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sum += skb_frag_size(frag++);
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sum += skb_frag_size(frag++);
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sum += skb_frag_size(frag++);
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/* Walk through fragments adding latest fragment, testing it, and
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* then removing stale fragments from the sum.
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*/
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stale = &skb_shinfo(skb)->frags[0];
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for (;;) {
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(frag++);
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/* if sum is negative we failed to make sufficient progress */
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if (sum < 0)
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@ -2655,7 +2654,7 @@ bool __i40e_chk_linearize(struct sk_buff *skb)
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if (!--nr_frags)
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break;
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sum -= skb_frag_size(++stale);
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sum -= skb_frag_size(stale++);
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}
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return false;
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@ -413,10 +413,14 @@ static inline int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
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**/
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static inline bool i40e_chk_linearize(struct sk_buff *skb, int count)
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{
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/* we can only support up to 8 data buffers for a single send */
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if (likely(count <= I40E_MAX_BUFFER_TXD))
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/* Both TSO and single send will work if count is less than 8 */
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if (likely(count < I40E_MAX_BUFFER_TXD))
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return false;
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if (skb_is_gso(skb))
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return __i40e_chk_linearize(skb);
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/* we can support up to 8 data buffers for a single send */
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return count != I40E_MAX_BUFFER_TXD;
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}
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#endif /* _I40E_TXRX_H_ */
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@ -1796,35 +1796,34 @@ static void i40e_create_tx_ctx(struct i40e_ring *tx_ring,
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}
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/**
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* __i40evf_chk_linearize - Check if there are more than 8 fragments per packet
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* __i40evf_chk_linearize - Check if there are more than 8 buffers per packet
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* @skb: send buffer
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*
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* Note: Our HW can't scatter-gather more than 8 fragments to build
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* a packet on the wire and so we need to figure out the cases where we
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* need to linearize the skb.
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* Note: Our HW can't DMA more than 8 buffers to build a packet on the wire
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* and so we need to figure out the cases where we need to linearize the skb.
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*
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* For TSO we need to count the TSO header and segment payload separately.
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* As such we need to check cases where we have 7 fragments or more as we
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* can potentially require 9 DMA transactions, 1 for the TSO header, 1 for
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* the segment payload in the first descriptor, and another 7 for the
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* fragments.
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**/
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bool __i40evf_chk_linearize(struct sk_buff *skb)
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{
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const struct skb_frag_struct *frag, *stale;
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int gso_size, nr_frags, sum;
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int nr_frags, sum;
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/* check to see if TSO is enabled, if so we may get a repreive */
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gso_size = skb_shinfo(skb)->gso_size;
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if (unlikely(!gso_size))
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return true;
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/* no need to check if number of frags is less than 8 */
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/* no need to check if number of frags is less than 7 */
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nr_frags = skb_shinfo(skb)->nr_frags;
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if (nr_frags < I40E_MAX_BUFFER_TXD)
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if (nr_frags < (I40E_MAX_BUFFER_TXD - 1))
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return false;
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/* We need to walk through the list and validate that each group
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* of 6 fragments totals at least gso_size. However we don't need
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* to perform such validation on the first or last 6 since the first
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* 6 cannot inherit any data from a descriptor before them, and the
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* last 6 cannot inherit any data from a descriptor after them.
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* to perform such validation on the last 6 since the last 6 cannot
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* inherit any data from a descriptor after them.
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*/
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nr_frags -= I40E_MAX_BUFFER_TXD - 1;
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nr_frags -= I40E_MAX_BUFFER_TXD - 2;
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frag = &skb_shinfo(skb)->frags[0];
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/* Initialize size to the negative value of gso_size minus 1. We
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@ -1833,21 +1832,21 @@ bool __i40evf_chk_linearize(struct sk_buff *skb)
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* descriptors for a single transmit as the header and previous
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* fragment are already consuming 2 descriptors.
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*/
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sum = 1 - gso_size;
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sum = 1 - skb_shinfo(skb)->gso_size;
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/* Add size of frags 1 through 5 to create our initial sum */
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(++frag);
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/* Add size of frags 0 through 4 to create our initial sum */
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sum += skb_frag_size(frag++);
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sum += skb_frag_size(frag++);
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sum += skb_frag_size(frag++);
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sum += skb_frag_size(frag++);
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sum += skb_frag_size(frag++);
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/* Walk through fragments adding latest fragment, testing it, and
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* then removing stale fragments from the sum.
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*/
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stale = &skb_shinfo(skb)->frags[0];
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for (;;) {
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sum += skb_frag_size(++frag);
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sum += skb_frag_size(frag++);
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/* if sum is negative we failed to make sufficient progress */
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if (sum < 0)
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@ -1857,7 +1856,7 @@ bool __i40evf_chk_linearize(struct sk_buff *skb)
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if (!--nr_frags)
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break;
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sum -= skb_frag_size(++stale);
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sum -= skb_frag_size(stale++);
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}
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return false;
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@ -395,10 +395,14 @@ static inline int i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size)
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**/
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static inline bool i40e_chk_linearize(struct sk_buff *skb, int count)
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{
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/* we can only support up to 8 data buffers for a single send */
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if (likely(count <= I40E_MAX_BUFFER_TXD))
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/* Both TSO and single send will work if count is less than 8 */
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if (likely(count < I40E_MAX_BUFFER_TXD))
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return false;
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if (skb_is_gso(skb))
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return __i40evf_chk_linearize(skb);
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/* we can support up to 8 data buffers for a single send */
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return count != I40E_MAX_BUFFER_TXD;
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}
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#endif /* _I40E_TXRX_H_ */
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