The PM core reacts badly when the return code from usb_runtime_suspend()
is not 0, -EAGAIN, or -EBUSY. The PM core regards this as a fatal error,
and refuses to run anymore PM helper functions. In particular,
usbfs_open() and other usbfs functions will fail because the PM core will
return an error code when usb_autoresume_device() is called. This causes
libusb and/or lsusb to either hang or segfault.
If a USB device cannot suspend for some reason (e.g. a hub doesn't report
it has remote wakeup capabilities), we still want lsusb and other
userspace programs to work. So return -EBUSY, which will fill people's
log files with failed tries, but will ensure userspace still works.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
---
drivers/usb/core/driver.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index b9278a1..a6d9297 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1660,6 +1660,11 @@ static int usb_runtime_suspend(struct device *dev)
return -EAGAIN;
status = usb_suspend_both(udev, PMSG_AUTO_SUSPEND);
+ /* The PM core reacts badly core unless the return code is 0,
+ * -EAGAIN, or -EBUSY, so always return -EBUSY on an error.
+ */
+ if (status != 0)
+ return -EBUSY;
return status;
}
--
1.6.3.3
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