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vmxnet3: avoid xmit reset due to a race in vmxnet3

Bladeren bron 
The field txNumDeferred is used by the driver to keep track of the number
of packets it has pushed to the emulation. The driver increments it on
pushing the packet to the emulation and the emulation resets it to 0 at
the end of the transmit.

There is a possibility of a race either when (a) ESX is under heavy load or
(b) workload inside VM is of low packet rate.

This race results in xmit hangs when network coalescing is disabled. This
change creates a local copy of txNumDeferred and uses it to perform ring
arithmetic.

Reported-by: Noriho Tanaka <ntanaka@vmware.com>
Signed-off-by: Ronak Doshi <doshir@vmware.com>
Acked-by: Shrikrishna Khare <skhare@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ronak Doshi
2018-03-16 14:47:54 -07:00
gecommit door David S. Miller
bovenliggende 78f1b04fa2
commit 7a4c003d69
2 gewijzigde bestanden met toevoegingen van 10 en 7 verwijderingen
Download Patch-bestand Download Diff-bestand Expand all files Collapse all files

13
drivers/net/vmxnet3/vmxnet3_drv.c
Bestand weergeven

@@ -977,6 +977,8 @@ vmxnet3_tq_xmit(struct sk_buff *skb, struct vmxnet3_tx_queue *tq,
{
int ret;
u32 count;
int num_pkts;
int tx_num_deferred;
unsigned long flags;
struct vmxnet3_tx_ctx ctx;
union Vmxnet3_GenericDesc *gdesc;
@@ -1075,12 +1077,12 @@ vmxnet3_tq_xmit(struct sk_buff *skb, struct vmxnet3_tx_queue *tq,
#else
gdesc = ctx.sop_txd;
#endif
tx_num_deferred = le32_to_cpu(tq->shared->txNumDeferred);
if (ctx.mss) {
gdesc->txd.hlen = ctx.eth_ip_hdr_size + ctx.l4_hdr_size;
gdesc->txd.om = VMXNET3_OM_TSO;
gdesc->txd.msscof = ctx.mss;
le32_add_cpu(&tq->shared->txNumDeferred, (skb->len -
gdesc->txd.hlen + ctx.mss - 1) / ctx.mss);
num_pkts = (skb->len - gdesc->txd.hlen + ctx.mss - 1) / ctx.mss;
} else {
if (skb->ip_summed == CHECKSUM_PARTIAL) {
gdesc->txd.hlen = ctx.eth_ip_hdr_size;
@@ -1091,8 +1093,10 @@ vmxnet3_tq_xmit(struct sk_buff *skb, struct vmxnet3_tx_queue *tq,
gdesc->txd.om = 0;
gdesc->txd.msscof = 0;
}
le32_add_cpu(&tq->shared->txNumDeferred, 1);
num_pkts = 1;
}
le32_add_cpu(&tq->shared->txNumDeferred, num_pkts);
tx_num_deferred += num_pkts;
if (skb_vlan_tag_present(skb)) {
gdesc->txd.ti = 1;
@@ -1118,8 +1122,7 @@ vmxnet3_tq_xmit(struct sk_buff *skb, struct vmxnet3_tx_queue *tq,
spin_unlock_irqrestore(&tq->tx_lock, flags);
if (le32_to_cpu(tq->shared->txNumDeferred) >=
le32_to_cpu(tq->shared->txThreshold)) {
if (tx_num_deferred >= le32_to_cpu(tq->shared->txThreshold)) {
tq->shared->txNumDeferred = 0;
VMXNET3_WRITE_BAR0_REG(adapter,
VMXNET3_REG_TXPROD + tq->qid * 8,