linux-stable/drivers/net/hyperv
Vitaly Kuznetsov 5362855aba netvsc: get rid of completion timeouts
I'm hitting 5 second timeout in rndis_filter_set_rss_param() while setting
RSS parameters for the device. When this happens we end up returning
-ETIMEDOUT from the function and rndis_filter_device_add() falls back to
setting

        net_device->max_chn = 1;
        net_device->num_chn = 1;
        net_device->num_sc_offered = 0;

but after a moment the rndis request succeeds and subchannels start to
appear. netvsc_sc_open() does unconditional nvscdev->num_sc_offered-- and
it becomes U32_MAX-1. Consequent rndis_filter_device_remove() will hang
while waiting for all U32_MAX-1 subchannels to appear and this is not
going to happen.

The immediate issue could be solved by adding num_sc_offered > 0 check to
netvsc_sc_open() but we're getting out of sync with the host and it's not
easy to adjust things later, e.g. in this particular case we'll be creating
queues without a user request for it and races are expected. Same applies
to other parts of the driver which have the same completion timeout.

Following the trend in drivers/hv/* code I suggest we remove all these
timeouts completely. As a guest we can always trust the host we're running
on and if the host screws things up there is no easy way to recover anyway.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-09 11:40:05 -07:00
..
hyperv_net.h hv_netvsc: pass struct net_device to rndis_filter_set_device_mac() 2016-06-05 23:16:36 -04:00
Kconfig
Makefile
netvsc.c netvsc: get rid of completion timeouts 2016-06-09 11:40:05 -07:00
netvsc_drv.c hv_netvsc: pass struct net_device to rndis_filter_set_device_mac() 2016-06-05 23:16:36 -04:00
rndis_filter.c netvsc: get rid of completion timeouts 2016-06-09 11:40:05 -07:00