Messages in this thread | | | Date | Thu, 7 May 2015 13:12:31 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH RFC 01/15] uaccess: count pagefault_disable() levels in pagefault_disabled |
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On Thu, May 07, 2015 at 12:50:53PM +0200, David Hildenbrand wrote: > Just to make sure we have a common understanding (as written in my cover > letter): > > Your suggestion won't work with !CONFIG_PREEMPT (!CONFIG_PREEMPT_COUNT). If > there is no preempt counter, in_atomic() won't work.
But there is, we _always_ have a preempt_count, and irq_enter() et al. _always_ increment the relevant bits.
The thread_info::preempt_count field it never under PREEMPT_COUNT include/asm-generic/preempt.h provides stuff regardless of PREEMPT_COUNT.
See how __irq_enter() -> preempt_count_add(HARDIRQ_OFFSET) -> __preempt_count_add() _always_ just works.
Its only things like preempt_disable() / preempt_enable() that get munged depending on PREEMPT_COUNT/PREEMPT.
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