On 05/14/2014 05:31 AM, Carlos O'Donell wrote: > On Sun, May 11, 2014 at 6:40 PM, John David Anglin <dave.anglin@xxxxxxxx> wrote: >> 2) Removes the lock code on UP systems where it is not needed, and > > This is wrong. The locking was originally only for SMP, but at one > point it was discovered that you could COW during the CAS operation > and if you didn't take the lock in UP, you could re-enter the CAS via > another task and thus incorrectly carry out the CAS in two different > threads and corrupt the state. While we attempt our best to prevent > the task running the CAS from being scheduled off, the COW operation > trap and subsequent scheduling is not something I could find an easy > way to prevent. Therefore the solution was to use locks for both UP > and SMP. If so, could one of you please send an updated patch to the list...? Currently I've scheduled http://git.kernel.org/cgit/linux/kernel/git/deller/parisc-linux.git/commit/?h=for-next&id=f4030047d92c79344ac4ca6ad4c6e3e22ceb5a55 for inclusion into the next kernel (hopefully 3.15). Helge -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
