wusbcore: reduce keepalive threshold from timeout/2 to timeout/3

This patch reduces the keepalive threshold of WUSB host controllers from
timeout/2 to timeout/3.  The keepalive timer fires every timeout/2 ms, but
due to rounding errors and jitter, the host may decide not to send a
keepalive at timeout/2.  By the time the next timer fires, a full timeout
period may have expired causing the device to be disconnected without ever
having been sent a keepalive.  Changing the keepalive threshold to
timeout/3 ensures that at least one keepalive will be sent before a device
is disconnected.  The patch also updates the code to use msecs_to_jiffies
consistently.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 5 insertions, 6 deletions

diff --git a/drivers/usb/wusbcore/devconnect.c b/drivers/usb/wusbcore/devconnect.c
index 1d365316960c..33a12788f9ca 100644
--- a/drivers/usb/wusbcore/devconnect.c
+++ b/drivers/usb/wusbcore/devconnect.c
@@ -455,8 +455,8 @@ static void __wusbhc_keep_alive(struct wusbhc *wusbhc)
                         dev_err(dev, "KEEPALIVE: device %u timed out\n",
                                 wusb_dev->addr);
                         __wusbhc_dev_disconnect(wusbhc, wusb_port);
-                } else if (time_after(jiffies, wusb_dev->entry_ts + tt/2)) {
-                        /* Approaching timeout cut out, need to refresh */
+                } else if (time_after(jiffies, wusb_dev->entry_ts + tt/3)) {
+                        /* Approaching timeout cut off, need to refresh */
                         ie->bDeviceAddress[keep_alives++] = wusb_dev->addr;
                 }
         }
@@ -1062,7 +1062,7 @@ int wusbhc_devconnect_start(struct wusbhc *wusbhc)
         wusbhc->wuie_host_info = hi;
 
         queue_delayed_work(wusbd, &wusbhc->keep_alive_timer,
-                           (wusbhc->trust_timeout*CONFIG_HZ)/1000/2);
+                           msecs_to_jiffies(wusbhc->trust_timeout / 2));
 
         return 0;
 
diff --git a/drivers/usb/wusbcore/wusbhc.c b/drivers/usb/wusbcore/wusbhc.c
index 0faca16df765..c35ee4394810 100644
--- a/drivers/usb/wusbcore/wusbhc.c
+++ b/drivers/usb/wusbcore/wusbhc.c
@@ -75,12 +75,11 @@ static ssize_t wusb_trust_timeout_store(struct device *dev,
                 result = -EINVAL;
                 goto out;
         }
-        /* FIXME: maybe we should check for range validity? */
-        wusbhc->trust_timeout = trust_timeout;
+        wusbhc->trust_timeout = min_t(unsigned, trust_timeout, 500);
         cancel_delayed_work(&wusbhc->keep_alive_timer);
         flush_workqueue(wusbd);
         queue_delayed_work(wusbd, &wusbhc->keep_alive_timer,
-                           (trust_timeout * CONFIG_HZ)/1000/2);
+                           msecs_to_jiffies(wusbhc->trust_timeout / 2));
 out:
         return result < 0 ? result : size;
 }