On Wed, 2014-04-30 at 10:04 -0400, Alan Stern wrote:
> On Tue, 29 Apr 2014, Dan Williams wrote:
>
> > > What happens if a thread tries to resume or suspend a port while the
> > > hub is being reset? With nothing to prevent it, the request sent to
> > > the hub will fail and the port may end up in a runtime PM error state.
> > >
> >
> > I'm expected to be protected by:
> >
> > /* Prevent autosuspend during the reset */
> > usb_autoresume_device(udev);
> >
> > ...in usb_reset_device() and usb_reset_and_verify_device()'s
> > requirement that the device in question not be suspended. The hub
> > should pin it's parent port active during the reset.
>
> My question wasn't clear enough. What happens if, while hub H is being
> reset, a thread tries to resume a port on hub H (not on H's parent)?
>
Ah, yes, I think we need something like the following. I'll fold it
into the re-submit.
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 943366345beb..02b0833b0a67 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -5183,6 +5183,31 @@ static int descriptors_changed(struct usb_device *udev,
return changed;
}
+static void usb_hub_ports_pm_get_sync(struct usb_device *hdev)
+{
+ struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
+ int port1;
+
+ for (port1 = 1; port1 <= hdev->maxchild; port1++) {
+ struct usb_port *port_dev = hub->ports[port1 - 1];
+
+ pm_runtime_get_sync(&port_dev->dev);
+ }
+}
+
+static void usb_hub_ports_pm_put(struct usb_device *hdev)
+{
+ struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
+ int port1;
+
+ for (port1 = 1; port1 <= hdev->maxchild; port1++) {
+ struct usb_port *port_dev = hub->ports[port1 - 1];
+
+ pm_runtime_put(&port_dev->dev);
+ }
+}
+
+
/**
* usb_reset_and_verify_device - perform a USB port reset to reinitialize a
device
* @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
@@ -5239,6 +5264,9 @@ static int usb_reset_and_verify_device(struct usb_device
*udev)
parent_hub = usb_hub_to_struct_hub(parent_hdev);
+ /* Disable usb_port power management */
+ usb_hub_ports_pm_get_sync(udev);
+
/* Disable USB2 hardware LPM.
* It will be re-enabled by the enumeration process.
*/
@@ -5358,9 +5386,11 @@ done:
usb_enable_ltm(udev);
usb_release_bos_descriptor(udev);
udev->bos = bos;
+ usb_hub_ports_pm_put(udev);
return 0;
re_enumerate:
+ usb_hub_ports_pm_put(udev);
/* LPM state doesn't matter when we're about to destroy the device. */
hub_port_logical_disconnect(parent_hub, port1);
usb_release_bos_descriptor(udev);
--
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