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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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern 2014-05-20 18:08:07 -07:00 committed by Greg Kroah-Hartman
parent 342a749341
commit 600856c231
3 changed files with 19 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/usb/core/hub.c
View File

@ -1276,12 +1276,22 @@ static void hub_quiesce(struct usb_hub *hub, enum hub_quiescing_type type)
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 */
static int hub_pre_reset(struct usb_interface *intf)
{
struct usb_hub *hub = usb_get_intfdata(intf);
hub_quiesce(hub, HUB_PRE_RESET);
hub->in_reset = 1;
hub_pm_barrier_for_all_ports(hub);
return 0;
}
@ -1290,6 +1300,8 @@ static int hub_post_reset(struct usb_interface *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);
return 0;
}

1
drivers/usb/core/hub.h
View File

@ -66,6 +66,7 @@ struct usb_hub {
unsigned limited_power:1;
unsigned quiescing:1;
unsigned disconnected:1;
unsigned in_reset:1;
unsigned quirk_check_port_auto_suspend:1;

6
drivers/usb/core/port.c
View File

@ -81,6 +81,10 @@ static int usb_port_runtime_resume(struct device *dev)
if (!hub)
return -EINVAL;
if (hub->in_reset) {
port_dev->power_is_on = 1;
return 0;
}
usb_autopm_get_interface(intf);
set_bit(port1, hub->busy_bits);
@ -117,6 +121,8 @@ static int usb_port_runtime_suspend(struct device *dev)
if (!hub)
return -EINVAL;
if (hub->in_reset)
return -EBUSY;
if (dev_pm_qos_flags(&port_dev->dev, PM_QOS_FLAG_NO_POWER_OFF)
== PM_QOS_FLAGS_ALL)