Yes, an alterative to the PF_CPU_BIND flag is to prevent calls to
set_cpus_allowed() for kthreads that should not change affinity.
I think we both agree that in terms of the code itself, adding the flag
and doing the check in set_cpus_allowed() is the optimal solution. It can
simply return -EINVAL for PF_CPU_BIND threads and the threads don't get
moved.
It's debatable whether allocating an additional PF_* flag for this purpose
is worthwhile.
I usually don't advocate against adding such bits that have a clear and
defined purpose for the sole reason that perhaps later we will need
additional bits that can't be worked around so easily as this one. It's
helpful to be conservative in allocating new flags but not at the expense
of the code itself, especially when loopholes can easily be introduced
that would have been otherwise prevented.
So I'll repost the patch and see where it goes.
David
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