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usb: Fail a get config when the port is powered off.

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Alan Stern pointed out that a USB port could potentially get powered off
when the attached USB device is in the middle of enumerating, due to
race conditions:
	http://marc.info/?l=linux-usb&m=134130616707548&w=2

If that happens, we need to ensure the enumeration fails.  If a call to
usb_get_descriptor() fails for a reason other than a Stall, return an
error.  That should handle the case where the port is powered off.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lan Tianyu 2012-09-05 13:44:37 +08:00 committed by Greg Kroah-Hartman
parent f7ac7787ad
commit 3a22b872e9
1 changed files with 2 additions and 0 deletions
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2
drivers/usb/core/config.c
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@ -702,6 +702,8 @@ int usb_get_configuration(struct usb_device *dev)
if (result < 0) {
dev_err(ddev, "unable to read config index %d "
"descriptor/%s: %d\n", cfgno, "start", result);
if (result != -EPIPE)
goto err;
dev_err(ddev, "chopping to %d config(s)\n", cfgno);
dev->descriptor.bNumConfigurations = cfgno;
break;