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>

2 files changed, 31 insertions, 100 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)
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 979fa4455f72..8e830f741d47 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -466,7 +466,6 @@ static int rndis_filter_query_device(struct rndis_device *dev, u32 oid,
         struct rndis_query_request *query;
         struct rndis_query_complete *query_complete;
         int ret = 0;
-        unsigned long t;
 
         if (!result)
                 return -EINVAL;
@@ -503,11 +502,7 @@ static int rndis_filter_query_device(struct rndis_device *dev, u32 oid,
         if (ret != 0)
                 goto cleanup;
 
-        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-        if (t == 0) {
-                ret = -ETIMEDOUT;
-                goto cleanup;
-        }
+        wait_for_completion(&request->wait_event);
 
         /* Copy the response back */
         query_complete = &request->response_msg.msg.query_complete;
@@ -556,7 +551,6 @@ int rndis_filter_set_device_mac(struct net_device *ndev, char *mac)
         u32 extlen = sizeof(struct rndis_config_parameter_info) +
                 2*NWADR_STRLEN + 4*ETH_ALEN;
         int ret;
-        unsigned long t;
 
         request = get_rndis_request(rdev, RNDIS_MSG_SET,
                 RNDIS_MESSAGE_SIZE(struct rndis_set_request) + extlen);
@@ -597,21 +591,13 @@ int rndis_filter_set_device_mac(struct net_device *ndev, char *mac)
         if (ret != 0)
                 goto cleanup;
 
-        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-        if (t == 0) {
-                netdev_err(ndev, "timeout before we got a set response...\n");
-                /*
-                 * can't put_rndis_request, since we may still receive a
-                 * send-completion.
-                 */
-                return -EBUSY;
-        } else {
-                set_complete = &request->response_msg.msg.set_complete;
-                if (set_complete->status != RNDIS_STATUS_SUCCESS) {
-                        netdev_err(ndev, "Fail to set MAC on host side:0x%x\n",
-                                   set_complete->status);
-                        ret = -EINVAL;
-                }
+        wait_for_completion(&request->wait_event);
+
+        set_complete = &request->response_msg.msg.set_complete;
+        if (set_complete->status != RNDIS_STATUS_SUCCESS) {
+                netdev_err(ndev, "Fail to set MAC on host side:0x%x\n",
+                           set_complete->status);
+                ret = -EINVAL;
         }
 
 cleanup:
@@ -631,7 +617,6 @@ rndis_filter_set_offload_params(struct net_device *ndev,
         struct rndis_set_complete *set_complete;
         u32 extlen = sizeof(struct ndis_offload_params);
         int ret;
-        unsigned long t;
         u32 vsp_version = nvdev->nvsp_version;
 
         if (vsp_version <= NVSP_PROTOCOL_VERSION_4) {
@@ -665,20 +650,12 @@ rndis_filter_set_offload_params(struct net_device *ndev,
         if (ret != 0)
                 goto cleanup;
 
-        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-        if (t == 0) {
-                netdev_err(ndev, "timeout before we got aOFFLOAD set response...\n");
-                /* can't put_rndis_request, since we may still receive a
-                 * send-completion.
-                 */
-                return -EBUSY;
-        } else {
-                set_complete = &request->response_msg.msg.set_complete;
-                if (set_complete->status != RNDIS_STATUS_SUCCESS) {
-                        netdev_err(ndev, "Fail to set offload on host side:0x%x\n",
-                                   set_complete->status);
-                        ret = -EINVAL;
-                }
+        wait_for_completion(&request->wait_event);
+        set_complete = &request->response_msg.msg.set_complete;
+        if (set_complete->status != RNDIS_STATUS_SUCCESS) {
+                netdev_err(ndev, "Fail to set offload on host side:0x%x\n",
+                           set_complete->status);
+                ret = -EINVAL;
         }
 
 cleanup:
@@ -706,7 +683,6 @@ static int rndis_filter_set_rss_param(struct rndis_device *rdev, int num_queue)
         u32 *itab;
         u8 *keyp;
         int i, ret;
-        unsigned long t;
 
         request = get_rndis_request(
                         rdev, RNDIS_MSG_SET,
@@ -749,20 +725,12 @@ static int rndis_filter_set_rss_param(struct rndis_device *rdev, int num_queue)
         if (ret != 0)
                 goto cleanup;
 
-        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-        if (t == 0) {
-                netdev_err(ndev, "timeout before we got a set response...\n");
-                /* can't put_rndis_request, since we may still receive a
-                 * send-completion.
-                 */
-                return -ETIMEDOUT;
-        } else {
-                set_complete = &request->response_msg.msg.set_complete;
-                if (set_complete->status != RNDIS_STATUS_SUCCESS) {
-                        netdev_err(ndev, "Fail to set RSS parameters:0x%x\n",
-                                   set_complete->status);
-                        ret = -EINVAL;
-                }
+        wait_for_completion(&request->wait_event);
+        set_complete = &request->response_msg.msg.set_complete;
+        if (set_complete->status != RNDIS_STATUS_SUCCESS) {
+                netdev_err(ndev, "Fail to set RSS parameters:0x%x\n",
+                           set_complete->status);
+                ret = -EINVAL;
         }
 
 cleanup:
@@ -791,8 +759,6 @@ int rndis_filter_set_packet_filter(struct rndis_device *dev, u32 new_filter)
         struct rndis_set_complete *set_complete;
         u32 status;
         int ret;
-        unsigned long t;
-        struct net_device *ndev = dev->ndev;
 
         request = get_rndis_request(dev, RNDIS_MSG_SET,
                         RNDIS_MESSAGE_SIZE(struct rndis_set_request) +
@@ -815,26 +781,14 @@ int rndis_filter_set_packet_filter(struct rndis_device *dev, u32 new_filter)
         if (ret != 0)
                 goto cleanup;
 
-        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+        wait_for_completion(&request->wait_event);
 
-        if (t == 0) {
-                netdev_err(ndev,
-                        "timeout before we got a set response...\n");
-                ret = -ETIMEDOUT;
-                /*
-                 * We can't deallocate the request since we may still receive a
-                 * send completion for it.
-                 */
-                goto exit;
-        } else {
-                set_complete = &request->response_msg.msg.set_complete;
-                status = set_complete->status;
-        }
+        set_complete = &request->response_msg.msg.set_complete;
+        status = set_complete->status;
 
 cleanup:
         if (request)
                 put_rndis_request(dev, request);
-exit:
         return ret;
 }
 
@@ -846,7 +800,6 @@ static int rndis_filter_init_device(struct rndis_device *dev)
         struct rndis_initialize_complete *init_complete;
         u32 status;
         int ret;
-        unsigned long t;
         struct netvsc_device *nvdev = net_device_to_netvsc_device(dev->ndev);
 
         request = get_rndis_request(dev, RNDIS_MSG_INIT,
@@ -870,12 +823,7 @@ static int rndis_filter_init_device(struct rndis_device *dev)
                 goto cleanup;
         }
 
-        t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-
-        if (t == 0) {
-                ret = -ETIMEDOUT;
-                goto cleanup;
-        }
+        wait_for_completion(&request->wait_event);
 
         init_complete = &request->response_msg.msg.init_complete;
         status = init_complete->status;
@@ -1008,7 +956,6 @@ int rndis_filter_device_add(struct hv_device *dev,
         struct netvsc_device_info *device_info = additional_info;
         struct ndis_offload_params offloads;
         struct nvsp_message *init_packet;
-        unsigned long t;
         struct ndis_recv_scale_cap rsscap;
         u32 rsscap_size = sizeof(struct ndis_recv_scale_cap);
         u32 mtu, size;
@@ -1151,11 +1098,8 @@ int rndis_filter_device_add(struct hv_device *dev,
                                VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
         if (ret)
                 goto out;
-        t = wait_for_completion_timeout(&net_device->channel_init_wait, 5*HZ);
-        if (t == 0) {
-                ret = -ETIMEDOUT;
-                goto out;
-        }
+        wait_for_completion(&net_device->channel_init_wait);
+
         if (init_packet->msg.v5_msg.subchn_comp.status !=
             NVSP_STAT_SUCCESS) {
                 ret = -ENODEV;
@@ -1192,17 +1136,12 @@ void rndis_filter_device_remove(struct hv_device *dev)
 {
         struct netvsc_device *net_dev = hv_device_to_netvsc_device(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");
-        }
+        if (net_dev->num_sc_offered > 0)
+                wait_for_completion(&net_dev->channel_init_wait);
 
         /* Halt and release the rndis device */
         rndis_filter_halt_device(rndis_dev);