Re: [DOCUMENTATION] Revised Unreliable Kernel Locking Guide

[Dave Jones]

On Sat, Dec 13, 2003 at 03:25:52AM +1100, Keith Owens wrote:
 > On Fri, 12 Dec 2003 15:44:01 +0000, 
 > Dave Jones <davej@xxxxxxxxxx> wrote:
 > > Might be worth mentioning in the Per-CPU data section that code doing
 > >operations on CPU registers (MSRs and the like) needs to be protected
 > >by an explicit preempt_disable() / preempt_enable() pair if it's doing
 > >operations that it expects to run on a specific CPU.
 > 
 > Also calls to smp_call_function() need to be wrapped in preempt_disable,
 > plus any work that is done on the current cpu before/after calling a
 > function on the other cpus.  Lack of preempt disable could result in
 > the operation being done twice on one cpu and not at all on another.

And where you want to do the same thing on every processor, there's a
handy on_each_cpu() which takes care of this for you.

		Dave

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