[PATCH 0/1] Decouple hub scanning and usb-id

[Andy Whitcroft]

We have been seeing very slow usb-id processes during boot.  When triggered
by udev we see usb-id take up to 5s to scan the devices in the reference
system.  Even with this being asyncronous to the wait-for-root we find
an overall boot penalty of approximatly 0.3s.  For LVM and encrypted root
we have to wait for this to complete before we can proceed leading to an
approximatly 5s delay.

This is triggered by new locking in the usb core to handle wireless
USB hubs.  The following patch moves the locking over to RCU slowing
the updates slightly but freeing the read-side.  This restores normal
behaviour on boot, and restores boot times.

For Lucid.

-apw

Andy Whitcroft (1):
  UBUNTU: SAUCE: khubd -- switch USB product/manufacturer/serial
    handling to RCU

 drivers/usb/core/hub.c   |   34 ++++++++++++++++++++++++++++------
 drivers/usb/core/sysfs.c |    6 +++---
 2 files changed, 31 insertions(+), 9 deletions(-)