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Don't free the work queue entry that we're using to hold the scatter-gather

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list on exit from the transmit path.  The scatter-gather list itself can be
asynchronously DMAed to the transmit hardware, and we could actually lock up
the transmitter if any of a number of races around this were lost.

Instead, let the PKO free the scatter-gather list when it is done with it, and
use the "i" bit in each segment of the packet to avoid having them go into the
FPA.

This fixes an unrecoverable transmit stall under transmit load.

MFC after:	3 days
This commit is contained in:
jmallett 2010-11-29 21:04:00 +00:00
parent 0ea34870f8
commit e4700dbe99
1 changed files with 8 additions and 4 deletions
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12
sys/mips/cavium/octe/ethernet-tx.c
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@ -143,6 +143,7 @@ int cvm_oct_xmit(struct mbuf *m, struct ifnet *ifp)
/* Build the PKO command */
pko_command.u64 = 0;
pko_command.s.segs = 1;
pko_command.s.dontfree = 1; /* Do not put this buffer into the FPA. */
work = NULL;
} else {
@ -164,6 +165,7 @@ int cvm_oct_xmit(struct mbuf *m, struct ifnet *ifp)
/* Build the PKO buffer pointer */
hw_buffer.u64 = 0;
hw_buffer.s.i = 1; /* Do not put this buffer into the FPA. */
hw_buffer.s.addr = cvmx_ptr_to_phys(n->m_data);
hw_buffer.s.pool = 0;
hw_buffer.s.size = n->m_len;
@ -182,12 +184,11 @@ int cvm_oct_xmit(struct mbuf *m, struct ifnet *ifp)
pko_command.u64 = 0;
pko_command.s.segs = segs;
pko_command.s.gather = 1;
pko_command.s.dontfree = 0; /* Put the WQE above back into the FPA. */
}
/* Finish building the PKO command */
pko_command.s.n2 = 1; /* Don't pollute L2 with the outgoing packet */
pko_command.s.dontfree = 1;
pko_command.s.reg0 = priv->fau+qos*4;
pko_command.s.reg0 = priv->fau+qos*4;
pko_command.s.total_bytes = m->m_pkthdr.len;
pko_command.s.size0 = CVMX_FAU_OP_SIZE_32;
@ -200,6 +201,11 @@ int cvm_oct_xmit(struct mbuf *m, struct ifnet *ifp)
pko_command.s.ipoffp1 = ETHER_HDR_LEN + 1;
}
/*
* XXX
* Could use a different free queue (and different FAU address) per
* core instead of per QoS, to reduce contention here.
*/
IF_LOCK(&priv->tx_free_queue[qos]);
if (USE_ASYNC_IOBDMA) {
/* Get the number of mbufs in use by the hardware */
@ -242,8 +248,6 @@ int cvm_oct_xmit(struct mbuf *m, struct ifnet *ifp)
/* Pass it to any BPF listeners. */
ETHER_BPF_MTAP(ifp, m);
}
if (work != NULL)
cvmx_fpa_free(work, CVMX_FPA_WQE_POOL, DONT_WRITEBACK(1));
/* Free mbufs not in use by the hardware */
if (_IF_QLEN(&priv->tx_free_queue[qos]) > in_use) {