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SubjectRe: [PATCH] Linux Kernel Markers 0.13 for 2.6.17
Mathieu Desnoyers wrote:
> Just as a precision :
>
> The following sequence (please refer to the code below for local symbols
> 1 and 2) :
>
> 1:
> preempt_disable()
> call (*__mark_call_##name)(format, ## args);
> preempt_enable_no_resched()
> 2:
>
> is insured because :
>
> 1 is part of an inline assembly with rw dependency on __marker_sequencer
> the call is surrounded by memory barriers.
> 2 is part of an inline assembly with rw dependency on __marker_sequencer
>

What do you mean the call is surrounded by memory barriers? Do you mean
a call has an implicit barrier, or something else?

Either way, this doesn't prevent some otherwise unrelated
non-memory-using code from being scheduled in there, which would not be
executed. The gcc manual really strongly discourages jumping between
inline asms, because they have basically unpredictable results.

J
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