On Thu, 2009-10-29 at 00:28 +0300, Valentine wrote: > Benjamin Herrenschmidt wrote: > > On Wed, 2009-10-28 at 22:19 +0300, Valentine wrote: > > > >> I'm just not sure that we need to clear HARDIRQEN here, since we don't > >> really hard-disable the the interrupts. > > > > We do, or rather, we come in with the interrupts hard disabled, no ? > > Yes, looks like the interrupts are disabled at this point (before > preempt_schedule_irq) most of the times, but we don't hard-disable them > here. We just soft-disable them to make preempt_schedule_irq happy. Even > if an interrupt fires, it will be hard-disabled and the hardirq flag > will be cleared by the exception handler right away. I just think that > there's no need to clear hardirq flag if we don't clear MSR_EE.
My point is that MSR_EE _is_ already clear... isn't it ? So either we set it back, or we clear HARDIRQEN to reflect it. It will be re-enable as soon as preempt_schedule_irq() calls local_irq_enable() which is soon enough anyways. Also that avoids perf interrupt sneaking in since those act as NMIs in that regard and -will- get in even when soft disabled. Cheers, Ben. > Thanks, > Val. > > > > Ben. > > > >> Thanks, > >> Val. > >> > >>> + TRACE_DISABLE_INTS > >>> + > >>> + /* Call the scheduler with soft IRQs off */ > >>> +1: bl .preempt_schedule_irq > >>> + > >>> + /* Hard-disable interrupts again (and update PACA) */ > >>> #ifdef CONFIG_PPC_BOOK3E > >>> - wrteei 1 > >>> - bl .preempt_schedule > >>> wrteei 0 > >>> #else > >>> - ori r10,r10,MSR_EE > >>> - mtmsrd r10,1 /* reenable interrupts */ > >>> - bl .preempt_schedule > >>> mfmsr r10 > >>> - clrrdi r9,r1,THREAD_SHIFT > >>> - rldicl r10,r10,48,1 /* disable interrupts again */ > >>> + rldicl r10,r10,48,1 > >>> rotldi r10,r10,16 > >>> mtmsrd r10,1 > >>> #endif /* CONFIG_PPC_BOOK3E */ > >>> + li r0,0 > >>> + stb r0,PACAHARDIRQEN(r13) > >>> + > >>> + /* Re-test flags and eventually loop */ > >>> + clrrdi r9,r1,THREAD_SHIFT > >>> ld r4,TI_FLAGS(r9) > >>> andi. r0,r4,_TIF_NEED_RESCHED > >>> bne 1b > >>> b restore > >>> > >>> user_work: > >>> -#endif > >>> +#endif /* CONFIG_PREEMPT */ > >>> + > >>> /* Enable interrupts */ > >>> #ifdef CONFIG_PPC_BOOK3E > >>> wrteei 1 > > > > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
