> that book explicitly covers your question. read chapter 2
> where it
> covers these irq functions.
as i said i'm reading the book and actully i did read that chapter.
for me, here's the exact line that needs clarification,
In chapter 2, page 42 last paragraph(starts with "However, if ..." )
here's the code snippet he's talking about.
Point A:
local_irq_disable();
/* critical section ...*/
local_irq_enable();
Author say, if irg are already disabled at Point A (see snippet above) then local_irq_enable() creates an unpleasant side effect of re-enabling interrupts rather than restoring interrupt state.
1) first what's the difference between re-enabling and restoring interrupt state.
2) so is disable interrupts twice a problem, or just enabling them when after they are diabled (which sounds like how it should be ) a problem.
hope i have made myself clear enough for you to respond.
TIA
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