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>

1 files changed, 3 insertions, 11 deletions

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 96f00c0261fa..6909c322de4e 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -244,7 +244,6 @@ static int netvsc_destroy_buf(struct hv_device *device)
 static int netvsc_init_buf(struct hv_device *device)
 {
 	int ret = 0;
-	unsigned long t;
 	struct netvsc_device *net_device;
 	struct nvsp_message *init_packet;
 	struct net_device *ndev;
@@ -305,9 +304,7 @@ static int netvsc_init_buf(struct hv_device *device)
 		goto cleanup;
 	}
 
-	t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);
-	BUG_ON(t == 0);
-
+	wait_for_completion(&net_device->channel_init_wait);
 
 	/* Check the response */
 	if (init_packet->msg.v1_msg.
@@ -390,8 +387,7 @@ static int netvsc_init_buf(struct hv_device *device)
 		goto cleanup;
 	}
 
-	t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);
-	BUG_ON(t == 0);
+	wait_for_completion(&net_device->channel_init_wait);
 
 	/* Check the response */
 	if (init_packet->msg.v1_msg.
@@ -445,7 +441,6 @@ static int negotiate_nvsp_ver(struct hv_device *device,
 {
 	struct net_device *ndev = hv_get_drvdata(device);
 	int ret;
-	unsigned long t;
 
 	memset(init_packet, 0, sizeof(struct nvsp_message));
 	init_packet->hdr.msg_type = NVSP_MSG_TYPE_INIT;
@@ -462,10 +457,7 @@ static int negotiate_nvsp_ver(struct hv_device *device,
 	if (ret != 0)
 		return ret;
 
-	t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);
-
-	if (t == 0)
-		return -ETIMEDOUT;
+	wait_for_completion(&net_device->channel_init_wait);
 
 	if (init_packet->msg.init_msg.init_complete.status !=
 	    NVSP_STAT_SUCCESS)