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    SubjectRe: [PATCH] SMP signal latency fix up.

    On Fri, 7 Nov 2003, Linus Torvalds wrote:

    > (It _looks_ obvious enough, but can you check that there are no pointers
    > that we might be following in the "is it running" checks that could be
    > stale because we don't hold the runqueue lock any more).

    the 'is it running' check is 'task_curr(p)', which in this circumstance is
    equivalent to the following test:

    per_cpu(runqueues, (cpu)).curr == p

    where 'cpu' is p->thread_info->cpu. All pointers dereferenced in this test
    are stable, because 1) send_signal() is always called within the siglock,
    which serializes with task exit 2) p->thread_info->cpu is always valid for
    the same reason.

    so this seems to be safe to me.

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