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Commit 600856c2 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: mutual exclusion for resetting a hub and power-managing a port 



The USB core doesn't properly handle mutual exclusion between
resetting a hub and changing the power states of the hub's ports.  We
need to avoid sending port-power requests to the hub while it is being
reset, because such requests cannot succeed.

This patch fixes the problem by keeping track of when a reset is in
progress.  At such times, attempts to suspend (power-off) a port will
fail immediately with -EBUSY, and calls to usb_port_runtime_resume()
will update the power_is_on flag and return immediately.  When the
reset is complete, hub_activate() will automatically restore each port
to the proper power state.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 342a7493

drivers/usb/core/hub.c

+12 −0
Original line number Original line Diff line number Diff line
@@ -1276,12 +1276,22 @@ static void hub_quiesce(struct usb_hub *hub, enum hub_quiescing_type type) 
		flush_work(&hub->tt.clear_work);

		flush_work(&hub->tt.clear_work);

}

}





static void hub_pm_barrier_for_all_ports(struct usb_hub *hub)

{

	int i;



	for (i = 0; i < hub->hdev->maxchild; ++i)

		pm_runtime_barrier(&hub->ports[i]->dev);

}



/* caller has locked the hub device */

/* caller has locked the hub device */

static int hub_pre_reset(struct usb_interface *intf)

static int hub_pre_reset(struct usb_interface *intf)

{

{

	struct usb_hub *hub = usb_get_intfdata(intf);

	struct usb_hub *hub = usb_get_intfdata(intf);





	hub_quiesce(hub, HUB_PRE_RESET);

	hub_quiesce(hub, HUB_PRE_RESET);

	hub->in_reset = 1;

	hub_pm_barrier_for_all_ports(hub);

	return 0;

	return 0;

}

}
@@ -1290,6 +1300,8 @@ static int hub_post_reset(struct usb_interface *intf) 
{

{

	struct usb_hub *hub = usb_get_intfdata(intf);

	struct usb_hub *hub = usb_get_intfdata(intf);





	hub->in_reset = 0;

	hub_pm_barrier_for_all_ports(hub);

	hub_activate(hub, HUB_POST_RESET);

	hub_activate(hub, HUB_POST_RESET);

	return 0;

	return 0;

}

}

drivers/usb/core/hub.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -66,6 +66,7 @@ struct usb_hub { 
	unsigned		limited_power:1;

	unsigned		limited_power:1;

	unsigned		quiescing:1;

	unsigned		quiescing:1;

	unsigned		disconnected:1;

	unsigned		disconnected:1;

	unsigned		in_reset:1;





	unsigned		quirk_check_port_auto_suspend:1;

	unsigned		quirk_check_port_auto_suspend:1;

drivers/usb/core/port.c

+6 −0
Original line number Original line Diff line number Diff line
@@ -81,6 +81,10 @@ static int usb_port_runtime_resume(struct device *dev) 




	if (!hub)

	if (!hub)

		return -EINVAL;

		return -EINVAL;

	if (hub->in_reset) {

		port_dev->power_is_on = 1;

		return 0;

	}





	usb_autopm_get_interface(intf);

	usb_autopm_get_interface(intf);

	set_bit(port1, hub->busy_bits);

	set_bit(port1, hub->busy_bits);
@@ -117,6 +121,8 @@ static int usb_port_runtime_suspend(struct device *dev) 




	if (!hub)

	if (!hub)

		return -EINVAL;

		return -EINVAL;

	if (hub->in_reset)

		return -EBUSY;





	if (dev_pm_qos_flags(&port_dev->dev, PM_QOS_FLAG_NO_POWER_OFF)

	if (dev_pm_qos_flags(&port_dev->dev, PM_QOS_FLAG_NO_POWER_OFF)

			== PM_QOS_FLAGS_ALL)

			== PM_QOS_FLAGS_ALL)