Re: 2.4.18 Preempt Freezeups

David S. Miller (davem@redhat.com)
Fri, 15 Mar 2002 00:51:55 -0800 (PST)


From: Ian Duggan <ian@ianduggan.net>
Date: Fri, 15 Mar 2002 00:38:37 -0800

What is required for preempt beyond "SMP safe" code? I thought the whole
idea was to make the preemptions transparent to other code by utilizing
the SMP critical regions?

Pre-empt makes things like per-cpu data structures require
preemption disables around cpu-local critical regions.

Code that works before just because it knows the data structure is
only even accessed by the current cpu doesn't work because preemption
can cause a context switch at any time.
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