From 7a4c003d6921e2af215f4790aa43a292bdc78be0 Mon Sep 17 00:00:00 2001 From: Ronak Doshi Date: Fri, 16 Mar 2018 14:47:54 -0700 Subject: vmxnet3: avoid xmit reset due to a race in vmxnet3 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 Signed-off-by: Ronak Doshi Acked-by: Shrikrishna Khare Signed-off-by: David S. Miller --- drivers/net/vmxnet3/vmxnet3_drv.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'drivers/net/vmxnet3/vmxnet3_drv.c') diff --git a/drivers/net/vmxnet3/vmxnet3_drv.c b/drivers/net/vmxnet3/vmxnet3_drv.c index 8b39c160743d..b466a422b72d 100644 --- a/drivers/net/vmxnet3/vmxnet3_drv.c +++ b/drivers/net/vmxnet3/vmxnet3_drv.c @@ -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, -- cgit v1.2.1