svn commit: r223989 - head/sys/dev/usb/input
Andriy Gapon
avg at FreeBSD.org
Mon Aug 29 13:25:12 UTC 2011
on 14/07/2011 00:07 Hans Petter Selasky said the following:
> Author: hselasky
> Date: Wed Jul 13 21:07:50 2011
> New Revision: 223989
> URL: http://svn.freebsd.org/changeset/base/223989
>
> Log:
> Fix for dump after shutdown with USB keyboard plugged in. It appears that the
> system timer is stopped during shutdown and that the pause() statement in ukbd
> causes infinite hang in this regard. The fix is to use mi_switch() instead of
> pause() to do the required task switch to ensure that the required USB processes
> get executed.
>
> Reported by: Mike_Karels at mcafee.com
> MFC after: 1 week
>
> Modified:
> head/sys/dev/usb/input/ukbd.c
>
> Modified: head/sys/dev/usb/input/ukbd.c
> ==============================================================================
> --- head/sys/dev/usb/input/ukbd.c Wed Jul 13 21:07:41 2011 (r223988)
> +++ head/sys/dev/usb/input/ukbd.c Wed Jul 13 21:07:50 2011 (r223989)
> @@ -59,6 +59,8 @@ __FBSDID("$FreeBSD$");
> #include <sys/callout.h>
> #include <sys/malloc.h>
> #include <sys/priv.h>
> +#include <sys/proc.h>
> +#include <sys/sched.h>
> #include <sys/kdb.h>
>
> #include <dev/usb/usb.h>
> @@ -386,6 +388,33 @@ ukbd_put_key(struct ukbd_softc *sc, uint
> }
>
> static void
> +ukbd_yield(void)
> +{
> + struct thread *td = curthread;
> + uint32_t old_prio;
> +
> + DROP_GIANT();
> +
> + thread_lock(td);
> +
> + /* get current priority */
> + old_prio = td->td_base_pri;
> +
> + /* set new priority */
> + sched_prio(td, td->td_user_pri);
> +
> + /* cause a task switch */
> + mi_switch(SW_INVOL | SWT_RELINQUISH, NULL);
> +
> + /* restore priority */
> + sched_prio(td, old_prio);
> +
> + thread_unlock(td);
> +
> + PICKUP_GIANT();
> +}
> +
Another question - why ukbd_yield() is needed?
Why kern_yield() would not be good here?
What are the priority manipulations in ukbd_yield?
Not saying that the code is incorrect, just that this is not explained in the
commit message.
--
Andriy Gapon
More information about the svn-src-all
mailing list