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hv_netvsc: Move subchannel waiting to rndis_filter_device_remove()

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During hot add, vmbus_device_register() is called from vmbus_onoffer(), on
the same workqueue as the subchannel offer message work-queue, so
subchannel offer won't be processed until the vmbus_device_register()/...
/netvsc_probe() is done.
Also, vmbus_device_register() is called with channel_mutex locked, which
prevents subchannel processing too. So the "waiting for sub-channel
processing" will not success in hot add case. But, in usual module loading,
the netvsc_probe() is called from different code path, and doesn't fail.

This patch resolves the deadlock during NIC hot-add, and speeds up NIC
loading time.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Haiyang Zhang 2016-03-04 15:07:43 -08:00 committed by David S. Miller
parent ab825adbaa
commit d66ab51442
1 changed files with 13 additions and 6 deletions
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19
drivers/net/hyperv/rndis_filter.c
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@ -1175,22 +1175,18 @@ int rndis_filter_device_add(struct hv_device *dev,
ret = rndis_filter_set_rss_param(rndis_device, net_device->num_chn);
/*
* Wait for the host to send us the sub-channel offers.
* Set the number of sub-channels to be received.
*/
spin_lock_irqsave(&net_device->sc_lock, flags);
sc_delta = num_rss_qs - (net_device->num_chn - 1);
net_device->num_sc_offered -= sc_delta;
spin_unlock_irqrestore(&net_device->sc_lock, flags);
while (net_device->num_sc_offered != 0) {
t = wait_for_completion_timeout(&net_device->channel_init_wait, 10*HZ);
if (t == 0)
WARN(1, "Netvsc: Waiting for sub-channel processing");
}
out:
if (ret) {
net_device->max_chn = 1;
net_device->num_chn = 1;
net_device->num_sc_offered = 0;
}
return 0; /* return 0 because primary channel can be used alone */
@ -1204,6 +1200,17 @@ void rndis_filter_device_remove(struct hv_device *dev)
{
struct netvsc_device *net_dev = hv_get_drvdata(dev);
struct rndis_device *rndis_dev = net_dev->extension;
unsigned long t;
/* If not all subchannel offers are complete, wait for them until
* completion to avoid race.
*/
while (net_dev->num_sc_offered > 0) {
t = wait_for_completion_timeout(&net_dev->channel_init_wait,
10 * HZ);
if (t == 0)
WARN(1, "Netvsc: Waiting for sub-channel processing");
}
/* Halt and release the rndis device */
rndis_filter_halt_device(rndis_dev);