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Commit d66ab514 authored by Haiyang Zhang's avatar Haiyang Zhang Committed by David S. Miller
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hv_netvsc: Move subchannel waiting to rndis_filter_device_remove() 



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: default avatarHaiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ab825adb

drivers/net/hyperv/rndis_filter.c

+13 −6
Original line number Original line Diff line number Diff line
@@ -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);

	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);

	spin_lock_irqsave(&net_device->sc_lock, flags);

	sc_delta = num_rss_qs - (net_device->num_chn - 1);

	sc_delta = num_rss_qs - (net_device->num_chn - 1);

	net_device->num_sc_offered -= sc_delta;

	net_device->num_sc_offered -= sc_delta;

	spin_unlock_irqrestore(&net_device->sc_lock, flags);

	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:

out:

	if (ret) {

	if (ret) {

		net_device->max_chn = 1;

		net_device->max_chn = 1;

		net_device->num_chn = 1;

		net_device->num_chn = 1;

		net_device->num_sc_offered = 0;

	}

	}





	return 0; /* return 0 because primary channel can be used alone */

	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 netvsc_device *net_dev = hv_get_drvdata(dev);

	struct rndis_device *rndis_dev = net_dev->extension;

	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 */

	/* Halt and release the rndis device */

	rndis_filter_halt_device(rndis_dev);

	rndis_filter_halt_device(rndis_dev);