Re: PATCH Multithreaded core dump support for the 2.5.14 (and 15) kernel.

Robert Love
2002-05-16T21:25:00Z

On Thu, 2002-05-16 at 14:32, Alan Cox wrote:
> > For this to happen that semaphore would have to held across schedule()'s.
> > The ONLY place I've seen that in the kernel is set_CPUs_allowed +
> > migration_thread.
>
> The 2.5 kernel is pre-emptible.

Indeed :)

But there is plenty of places in the kernel - sans preemption - where we
sleep while holding a semaphore. Was that the original question? If
so, set_cpus_allowed by be one of the few _explicit_ places but we
implicitly sleep holding a semaphore all over. Heck, we use them for
user-space synchronization.

Robert Love