lkml.org 
[lkml]   [2011]   [Aug]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] uio/gen-pci: don't enable interrupts in ISR
    On Tue, Aug 09, 2011 at 01:43:46PM +0200, Sebastian Andrzej Siewior wrote:
    > Michael S. Tsirkin wrote:
    > >>It seems to me that you could drop this "user block" thing
    > >>since you never change anything outside of this command register and it
    > >>does not stop the race.
    > >
    > >I don't think so: if we did, we would lose userspace modifications to
    > >other bits such as io enable, and there's no way to guess what their
    > >values should be.
    >
    > How so?
    >
    > Sebastian

    Let's assume we start with e.g. io enable bit cleared.


    user kernel
    read config |
    set io enable |
    | interrupt
    | read + set interrupt mask
    write config back |
    write



    We end up with io enable bit cleared. Locking around rmw
    that we have fixes this race.

    --
    MST


    \
     
     \ /
      Last update: 2011-08-09 14:03    [W:0.021 / U:211.932 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site