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Commit 7d9852a8 authored by Thomas Pugliese's avatar Thomas Pugliese Committed by Greg Kroah-Hartman
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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: default avatarThomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d9ea21a7

drivers/usb/wusbcore/devconnect.c

+3 −3
Original line number Diff line number Diff line
@@ -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;

drivers/usb/wusbcore/wusbhc.c

+2 −3
Original line number Diff line number Diff line
@@ -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;

}