From: Tim Sell <timothy.s...@unisys.com>

Add error message to genuine rare error paths, and debug messages
to enable relatively non-verbose tracing of code paths

You can enable debug messages by including this on the kernel command line:

    visornic.dyndbg=+p

or by this from the command line:

    echo "module visornic +p" > <debugfs>/dynamic_debug/control

Refer to Documentation/dynamic-debug-howto.txt for more details.

In addition to the new debug and error messages, a message like the
following will be logged every time a visornic device is probed, which
will enable you to map back-and-forth between visorbus device names
(e.g., "vbus2:dev0") and netdev names (e.g., "eth0"):

    visornic vbus2:dev0: visornic_probe success netdev=eth0

With this patch and visornic debugging enabled, you should expect to see
messages like the following in the most-common scenarios:

* driver loaded:

      visornic_init

* device probed:

      visornic vbus2:dev0: visornic_probe
      visor_thread_start
      visor_thread_start success

* network interface configured (ifconfig):

      net eth0: visornic_open
      net eth0: visornic_enable_with_timeout
      net eth0: visornic_enable_with_timeout success
      net eth0: visornic_open success

staging: unisys: More comments from Jes

Signed-off-by: Tim Sell <timothy.s...@unisys.com>
Signed-off-by: David Kershner <david.kersh...@unisys.com>
Signed-off-by: Benjamin Romer <benjamin.ro...@unisys.com>
---
 drivers/staging/unisys/visornic/visornic_main.c | 127 ++++++++++++++++++++++--
 1 file changed, 116 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/unisys/visornic/visornic_main.c 
b/drivers/staging/unisys/visornic/visornic_main.c
index 7100744..7b9821c 100644
--- a/drivers/staging/unisys/visornic/visornic_main.c
+++ b/drivers/staging/unisys/visornic/visornic_main.c
@@ -294,14 +294,18 @@ static int visor_thread_start(struct visor_thread_info 
*thrinfo,
                              int (*threadfn)(void *),
                              void *thrcontext, char *name)
 {
+       pr_debug("%s\n", __func__);
        /* used to stop the thread */
        init_completion(&thrinfo->has_stopped);
        thrinfo->task = kthread_run(threadfn, thrcontext, name);
        if (IS_ERR(thrinfo->task)) {
+               pr_debug("%s failed (%ld)\n",
+                        __func__, PTR_ERR(thrinfo->task));
                thrinfo->id = 0;
                return -EINVAL;
        }
        thrinfo->id = thrinfo->task->pid;
+       pr_debug("%s success\n", __func__);
        return 0;
 }
 
@@ -317,10 +321,12 @@ static void visor_thread_stop(struct visor_thread_info 
*thrinfo)
        if (!thrinfo->id)
                return; /* thread not running */
 
+       pr_debug("%s\n", __func__);
        kthread_stop(thrinfo->task);
        /* give up if the thread has NOT died in 1 minute */
        if (wait_for_completion_timeout(&thrinfo->has_stopped, 60 * HZ))
                thrinfo->id = 0;
+       pr_debug("%s success\n", __func__);
 }
 
 /* DebugFS code */
@@ -333,6 +339,7 @@ static ssize_t info_debugfs_read(struct file *file, char 
__user *buf,
        struct visornic_devdata *devdata;
        char *vbuf;
 
+       pr_debug("%s\n", __func__);
        if (len > MAX_BUF)
                len = MAX_BUF;
        vbuf = kzalloc(len, GFP_KERNEL);
@@ -465,6 +472,8 @@ static ssize_t info_debugfs_read(struct file *file, char 
__user *buf,
        }
        bytes_read = simple_read_from_buffer(buf, len, offset, vbuf, str_pos);
        kfree(vbuf);
+       pr_debug("%s success %ld\n",
+                __func__, (long)bytes_read);
        return bytes_read;
 }
 
@@ -520,6 +529,8 @@ visornic_serverdown_complete(struct work_struct *work)
                               serverdown_completion);
        netdev = devdata->netdev;
 
+       dev_dbg(&netdev->dev, "%s\n", __func__);
+
        /* Stop using datachan */
        visor_thread_stop(&devdata->threadinfo);
 
@@ -547,6 +558,7 @@ visornic_serverdown_complete(struct work_struct *work)
 
        devdata->server_down = true;
        devdata->server_change_state = false;
+       dev_dbg(&netdev->dev, "%s success\n", __func__);
 }
 
 /**
@@ -560,13 +572,17 @@ visornic_serverdown_complete(struct work_struct *work)
 static int
 visornic_serverdown(struct visornic_devdata *devdata)
 {
+       dev_dbg(&devdata->dev->device, "%s\n", __func__);
        if (!devdata->server_down && !devdata->server_change_state) {
                devdata->server_change_state = true;
                queue_work(visornic_serverdown_workqueue,
                           &devdata->serverdown_completion);
        } else if (devdata->server_change_state) {
+               dev_dbg(&devdata->dev->device, "%s changing state\n",
+                       __func__);
                return -EINVAL;
        }
+       dev_dbg(&devdata->dev->device, "%s success\n", __func__);
        return 0;
 }
 
@@ -676,6 +692,8 @@ visornic_disable_with_timeout(struct net_device *netdev, 
const int timeout)
        unsigned long flags;
        int wait = 0;
 
+       dev_dbg(&netdev->dev, "%s\n", __func__);
+
        /* stop the transmit queue so nothing more can be transmitted */
        netif_stop_queue(netdev);
 
@@ -701,6 +719,8 @@ visornic_disable_with_timeout(struct net_device *netdev, 
const int timeout)
                        break;
                if (devdata->server_down || devdata->server_change_state) {
                        spin_unlock_irqrestore(&devdata->priv_lock, flags);
+                       dev_dbg(&netdev->dev, "%s server went away\n",
+                               __func__);
                        return -EIO;
                }
                set_current_state(TASK_INTERRUPTIBLE);
@@ -743,6 +763,7 @@ visornic_disable_with_timeout(struct net_device *netdev, 
const int timeout)
                        break;
                }
 
+       dev_dbg(&netdev->dev, "%s success\n", __func__);
        return 0;
 }
 
@@ -810,12 +831,17 @@ visornic_enable_with_timeout(struct net_device *netdev, 
const int timeout)
        unsigned long flags;
        int wait = 0;
 
+       dev_dbg(&netdev->dev, "%s\n", __func__);
+
        /* NOTE: the other end automatically unposts the rcv buffers when it
         * gets a disable.
         */
        i = init_rcv_bufs(netdev, devdata);
-       if (i < 0)
+       if (i < 0) {
+               dev_err(&netdev->dev,
+                       "%s failed to init rcv bufs (%d)\n", __func__, i);
                return i;
+       }
 
        spin_lock_irqsave(&devdata->priv_lock, flags);
        devdata->enabled = 1;
@@ -838,6 +864,8 @@ visornic_enable_with_timeout(struct net_device *netdev, 
const int timeout)
                        break;
                if (devdata->server_down || devdata->server_change_state) {
                        spin_unlock_irqrestore(&devdata->priv_lock, flags);
+                       dev_dbg(&netdev->dev, "%s server went away\n",
+                               __func__);
                        return -EIO;
                }
                set_current_state(TASK_INTERRUPTIBLE);
@@ -848,8 +876,10 @@ visornic_enable_with_timeout(struct net_device *netdev, 
const int timeout)
 
        spin_unlock_irqrestore(&devdata->priv_lock, flags);
 
-       if (!devdata->enab_dis_acked)
+       if (!devdata->enab_dis_acked) {
+               dev_err(&netdev->dev, "%s missing ACK\n", __func__);
                return -EIO;
+       }
 
        /* find an open slot in the array to save off VisorNic references
         * for debug
@@ -861,6 +891,7 @@ visornic_enable_with_timeout(struct net_device *netdev, 
const int timeout)
                }
        }
 
+       dev_dbg(&netdev->dev, "%s success\n", __func__);
        return 0;
 }
 
@@ -882,6 +913,7 @@ visornic_timeout_reset(struct work_struct *work)
        devdata = container_of(work, struct visornic_devdata, timeout_reset);
        netdev = devdata->netdev;
 
+       dev_dbg(&netdev->dev, "%s\n", __func__);
        netif_stop_queue(netdev);
        response = visornic_disable_with_timeout(netdev, 100);
        if (response)
@@ -896,6 +928,7 @@ visornic_timeout_reset(struct work_struct *work)
 
 call_serverdown:
        visornic_serverdown(devdata);
+       dev_dbg(&netdev->dev, "%s success\n", __func__);
 }
 
 /**
@@ -908,6 +941,7 @@ call_serverdown:
 static int
 visornic_open(struct net_device *netdev)
 {
+       dev_dbg(&netdev->dev, "%s\n", __func__);
        visornic_enable_with_timeout(netdev, VISORNIC_INFINITE_RESPONSE_WAIT);
 
        /* start the interface's transmit queue, allowing it to accept
@@ -915,6 +949,7 @@ visornic_open(struct net_device *netdev)
         */
        netif_start_queue(netdev);
 
+       dev_dbg(&netdev->dev, "%s success\n", __func__);
        return 0;
 }
 
@@ -928,9 +963,11 @@ visornic_open(struct net_device *netdev)
 static int
 visornic_close(struct net_device *netdev)
 {
+       dev_dbg(&netdev->dev, "%s\n", __func__);
        netif_stop_queue(netdev);
        visornic_disable_with_timeout(netdev, VISORNIC_INFINITE_RESPONSE_WAIT);
 
+       dev_dbg(&netdev->dev, "%s success\n", __func__);
        return 0;
 }
 
@@ -961,6 +998,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device 
*netdev)
            devdata->server_change_state) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
+               dev_dbg(&netdev->dev,
+                       "%s busy - queue stopped\n", __func__);
                return NETDEV_TX_BUSY;
        }
 
@@ -979,6 +1018,9 @@ visornic_xmit(struct sk_buff *skb, struct net_device 
*netdev)
        if (firstfraglen < ETH_HEADER_SIZE) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
+               dev_err(&netdev->dev,
+                       "%s busy - first frag too small (%d)\n",
+                       __func__, firstfraglen);
                return NETDEV_TX_BUSY;
        }
 
@@ -1018,6 +1060,9 @@ visornic_xmit(struct sk_buff *skb, struct net_device 
*netdev)
                netif_stop_queue(netdev);
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
+               dev_dbg(&netdev->dev,
+                       "%s busy - waiting for iovm to catch up\n",
+                       __func__);
                return NETDEV_TX_BUSY;
        }
        if (devdata->queuefullmsg_logged)
@@ -1058,6 +1103,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device 
*netdev)
        if (cmdrsp->net.xmt.num_frags == -1) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
+               dev_err(&netdev->dev,
+                       "%s busy - copy frags failed\n", __func__);
                return NETDEV_TX_BUSY;
        }
 
@@ -1066,6 +1113,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device 
*netdev)
                netif_stop_queue(netdev);
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
+               dev_dbg(&netdev->dev,
+                       "%s busy - signalinsert failed\n", __func__);
                return NETDEV_TX_BUSY;
        }
 
@@ -1098,6 +1147,9 @@ visornic_xmit(struct sk_buff *skb, struct net_device 
*netdev)
                                           * netif_wake_queue() after lower
                                           * threshold
                                           */
+               dev_dbg(&netdev->dev,
+                       "%s busy - invoking iovm flow control\n",
+                       __func__);
                devdata->flow_control_upper_hits++;
        }
        spin_unlock_irqrestore(&devdata->priv_lock, flags);
@@ -1200,16 +1252,20 @@ visornic_xmit_timeout(struct net_device *netdev)
        struct visornic_devdata *devdata = netdev_priv(netdev);
        unsigned long flags;
 
+       dev_dbg(&netdev->dev, "%s\n", __func__);
        spin_lock_irqsave(&devdata->priv_lock, flags);
        /* Ensure that a ServerDown message hasn't been received */
        if (!devdata->enabled ||
            (devdata->server_down && !devdata->server_change_state)) {
+               dev_dbg(&netdev->dev, "%s no processing\n",
+                       __func__);
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                return;
        }
        spin_unlock_irqrestore(&devdata->priv_lock, flags);
 
        queue_work(visornic_timeout_reset_workqueue, &devdata->timeout_reset);
+       dev_dbg(&netdev->dev, "%s success\n", __func__);
 }
 
 /**
@@ -1800,9 +1856,13 @@ static int visornic_probe(struct visor_device *dev)
        int channel_offset = 0;
        u64 features;
 
+       dev_dbg(&dev->device, "%s\n", __func__);
        netdev = alloc_etherdev(sizeof(struct visornic_devdata));
-       if (!netdev)
+       if (!netdev) {
+               dev_err(&dev->device,
+                       "%s alloc_etherdev failed\n", __func__);
                return -ENOMEM;
+       }
 
        netdev->netdev_ops = &visornic_dev_ops;
        netdev->watchdog_timeo = (5 * HZ);
@@ -1814,11 +1874,17 @@ static int visornic_probe(struct visor_device *dev)
                                  vnic.macaddr);
        err = visorbus_read_channel(dev, channel_offset, netdev->dev_addr,
                                    ETH_ALEN);
-       if (err < 0)
+       if (err < 0) {
+               dev_err(&dev->device,
+                       "%s failed to get mac addr from chan (%d)\n",
+                       __func__, err);
                goto cleanup_netdev;
+       }
 
        devdata = devdata_initialize(netdev_priv(netdev), dev);
        if (!devdata) {
+               dev_err(&dev->device,
+                       "%s devdata_initialize failed\n", __func__);
                err = -ENOMEM;
                goto cleanup_netdev;
        }
@@ -1834,8 +1900,12 @@ static int visornic_probe(struct visor_device *dev)
                                  vnic.num_rcv_bufs);
        err = visorbus_read_channel(dev, channel_offset,
                                    &devdata->num_rcv_bufs, 4);
-       if (err)
+       if (err) {
+               dev_err(&dev->device,
+                       "%s failed to get #rcv bufs from chan (%d)\n",
+                       __func__, err);
                goto cleanup_netdev;
+       }
 
        devdata->rcvbuf = kmalloc(sizeof(struct sk_buff *) *
                                  devdata->num_rcv_bufs, GFP_KERNEL);
@@ -1876,38 +1946,58 @@ static int visornic_probe(struct visor_device *dev)
        channel_offset = offsetof(struct spar_io_channel_protocol,
                                  vnic.mtu);
        err = visorbus_read_channel(dev, channel_offset, &netdev->mtu, 4);
-       if (err)
+       if (err) {
+               dev_err(&dev->device,
+                       "%s failed to get mtu from chan (%d)\n",
+                       __func__, err);
                goto cleanup_xmit_cmdrsp;
+       }
 
        /* TODO: Setup Interrupt information */
        /* Let's start our threads to get responses */
        channel_offset = offsetof(struct spar_io_channel_protocol,
                                  channel_header.features);
        err = visorbus_read_channel(dev, channel_offset, &features, 8);
-       if (err)
+       if (err) {
+               dev_err(&dev->device,
+                       "%s failed to get features from chan (%d)\n",
+                       __func__, err);
                goto cleanup_xmit_cmdrsp;
+       }
 
        features |= ULTRA_IO_CHANNEL_IS_POLLING;
        err = visorbus_write_channel(dev, channel_offset, &features, 8);
-       if (err)
+       if (err) {
+               dev_err(&dev->device,
+                       "%s failed to set features in chan (%d)\n",
+                       __func__, err);
                goto cleanup_xmit_cmdrsp;
+       }
 
        devdata->thread_wait_ms = 2;
        visor_thread_start(&devdata->threadinfo, process_incoming_rsps,
                           devdata, "vnic_incoming");
 
        err = register_netdev(netdev);
-       if (err)
+       if (err) {
+               dev_err(&dev->device,
+                       "%s register_netdev failed (%d)\n", __func__, err);
                goto cleanup_thread_stop;
+       }
 
        /* create debgug/sysfs directories */
        devdata->eth_debugfs_dir = debugfs_create_dir(netdev->name,
                                                      visornic_debugfs_dir);
        if (!devdata->eth_debugfs_dir) {
+               dev_err(&dev->device,
+                       "%s debugfs_create_dir %s failed\n",
+                       __func__, netdev->name);
                err = -ENOMEM;
                goto cleanup_thread_stop;
        }
 
+       dev_info(&dev->device, "%s success netdev=%s\n",
+                __func__, netdev->name);
        return 0;
 
 cleanup_thread_stop:
@@ -1955,8 +2045,11 @@ static void visornic_remove(struct visor_device *dev)
 {
        struct visornic_devdata *devdata = dev_get_drvdata(&dev->device);
 
-       if (!devdata)
+       if (!devdata) {
+               dev_err(&dev->device, "%s no devdata\n", __func__);
                return;
+       }
+       dev_dbg(&dev->device, "%s\n", __func__);
        dev_set_drvdata(&dev->device, NULL);
        host_side_disappeared(devdata);
        kref_put(&devdata->kref, devdata_release);
@@ -1980,8 +2073,10 @@ static int visornic_pause(struct visor_device *dev,
 {
        struct visornic_devdata *devdata = dev_get_drvdata(&dev->device);
 
+       dev_dbg(&dev->device, "%s\n", __func__);
        visornic_serverdown(devdata);
        complete_func(dev, 0);
+       dev_dbg(&dev->device, "%s success\n", __func__);
        return 0;
 }
 
@@ -2003,10 +2098,13 @@ static int visornic_resume(struct visor_device *dev,
        unsigned long flags;
 
        devdata = dev_get_drvdata(&dev->device);
-       if (!devdata)
+       if (!devdata) {
+               dev_err(&dev->device, "%s no devdata\n", __func__);
                return -EINVAL;
+       }
 
        netdev = devdata->netdev;
+       dev_dbg(&dev->device, "%s\n", __func__);
 
        if (devdata->server_down && !devdata->server_change_state) {
                devdata->server_change_state = true;
@@ -2032,10 +2130,13 @@ static int visornic_resume(struct visor_device *dev,
                 */
                send_enbdis(netdev, 1, devdata);
        } else if (devdata->server_change_state) {
+               dev_err(&dev->device, "%s server_change_state\n",
+                       __func__);
                return -EIO;
        }
 
        complete_func(dev, 0);
+       dev_dbg(&dev->device, "%s success\n", __func__);
        return 0;
 }
 
@@ -2051,6 +2152,8 @@ static int visornic_init(void)
        struct dentry *ret;
        int err = -ENOMEM;
 
+       pr_debug("%s\n", __func__);
+
        /* create workqueue for serverdown completion */
        visornic_serverdown_workqueue =
                create_singlethread_workqueue("visornic_serverdown");
@@ -2116,6 +2219,8 @@ cleanup_debugfs:
  */
 static void visornic_cleanup(void)
 {
+       pr_debug("%s\n", __func__);
+
        if (visornic_serverdown_workqueue) {
                flush_workqueue(visornic_serverdown_workqueue);
                destroy_workqueue(visornic_serverdown_workqueue);
-- 
2.1.4

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