[PATCH 3.4 26/35] vmxnet3: fix netpoll race condition

Greg Kroah-Hartman
2014-03-21T00:12:40Z

From: Neil Horman <nhorman@tuxdriver.com>

commit d25f06ea466ea521b563b76661180b4e44714ae6 upstream.

vmxnet3's netpoll driver is incorrectly coded. It directly calls
vmxnet3_do_poll, which is the driver internal napi poll routine. As the netpoll
controller method doesn't block real napi polls in any way, there is a potential
for race conditions in which the netpoll controller method and the napi poll
method run concurrently. The result is data corruption causing panics such as this
one recently observed:
PID: 1371 TASK: ffff88023762caa0 CPU: 1 COMMAND: "rs:main Q:Reg"
#0 [ffff88023abd5780] machine_kexec at ffffffff81038f3b
#1 [ffff88023abd57e0] crash_kexec at ffffffff810c5d92
#2 [ffff88023abd58b0] oops_end at ffffffff8152b570
#3 [ffff88023abd58e0] die at ffffffff81010e0b
#4 [ffff88023abd5910] do_trap at ffffffff8152add4
#5 [ffff88023abd5970] do_invalid_op at ffffffff8100cf95
#6 [ffff88023abd5a10] invalid_op at ffffffff8100bf9b
[exception RIP: vmxnet3_rq_rx_complete+1968]
RIP: ffffffffa00f1e80 RSP: ffff88023abd5ac8 RFLAGS: 00010086
RAX: 0000000000000000 RBX: ffff88023b5dcee0 RCX: 00000000000000c0
RDX: 0000000000000000 RSI: 00000000000005f2 RDI: ffff88023b5dcee0
RBP: ffff88023abd5b48 R8: 0000000000000000 R9: ffff88023a3b6048
R10: 0000000000000000 R11: 0000000000000002 R12: ffff8802398d4cd8
R13: ffff88023af35140 R14: ffff88023b60c890 R15: 0000000000000000
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#7 [ffff88023abd5b50] vmxnet3_do_poll at ffffffffa00f204a [vmxnet3]
#8 [ffff88023abd5b80] vmxnet3_netpoll at ffffffffa00f209c [vmxnet3]
#9 [ffff88023abd5ba0] netpoll_poll_dev at ffffffff81472bb7

The fix is to do as other drivers do, and have the poll controller call the top
half interrupt handler, which schedules a napi poll properly to recieve frames

Tested by myself, successfully.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Shreyas Bhatewara <sbhatewara@vmware.com>
CC: "VMware, Inc." <pv-drivers@vmware.com>
CC: "David S. Miller" <davem@davemloft.net>
Reviewed-by: Shreyas N Bhatewara <sbhatewara@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/vmxnet3/vmxnet3_drv.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

--- a/drivers/net/vmxnet3/vmxnet3_drv.c
+++ b/drivers/net/vmxnet3/vmxnet3_drv.c
@@ -1728,12 +1728,18 @@ static void
vmxnet3_netpoll(struct net_device *netdev)
{
struct vmxnet3_adapter *adapter = netdev_priv(netdev);
+ int i;

- if (adapter->intr.mask_mode == VMXNET3_IMM_ACTIVE)
- vmxnet3_disable_all_intrs(adapter);
-
- vmxnet3_do_poll(adapter, adapter->rx_queue[0].rx_ring[0].size);
- vmxnet3_enable_all_intrs(adapter);
+ switch (adapter->intr.type) {
+ case VMXNET3_IT_MSIX:
+ for (i = 0; i < adapter->num_rx_queues; i++)
+ vmxnet3_msix_rx(0, &adapter->rx_queue[i]);
+ break;
+ case VMXNET3_IT_MSI:
+ default:
+ vmxnet3_intr(0, adapter->netdev);
+ break;
+ }

}
#endif /* CONFIG_NET_POLL_CONTROLLER */