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    SubjectRe: [Cbe-oss-dev] [PATCH 14/22] spufs: use SPU master control to prevent wild SPU execution
    On Thursday 01 March 2007, Michael Ellerman wrote:
    > On Mon, 2006-11-20 at 18:45 +0100, Arnd Bergmann wrote:
    > > plain text document attachment (spufs-master-control.diff)
    > > When the user changes the runcontrol register, an SPU might be
    > > running without a process being attached to it and waiting for
    > > events. In order to prevent this, make sure we always disable
    > > the priv1 master control when we're not inside of spu_run.
    > Hi Arnd,
    > Sorry I didn't comment on this when you sent it, I wasn't paying enough
    > attention. This patch confuses me, you say we should make sure we always
    > disable the master control when we're not inside spu_run, but I see
    > several exit paths where we leave the master run bit enabled - or maybe
    > I'm reading it wrong.

    I think you're right, there is at least one path that I now saw
    getting out of spufs_run_spu incorrectly. In particular, when
    spu_reacquire_runnable() fails, we never call the master stop,
    which is a bug, but should happen very infrequently in practice.
    Do you see another case where we end up with the same problem?

    If not, I'll prepare a patch to fix this one case.

    Arnd <><

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