Messages in this thread | | | Date | Thu, 1 Aug 2019 08:37:37 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v3 3/4] arm64: Make debug exception handlers visible from RCU |
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Hi Masami,
On Thu, Aug 01, 2019 at 02:32:25PM +0900, Masami Hiramatsu wrote: > On Wed, 31 Jul 2019 18:26:03 +0100 > Will Deacon <will@kernel.org> wrote: > > On Thu, Jul 25, 2019 at 05:16:15PM +0900, Masami Hiramatsu wrote: > > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > > > index 9568c116ac7f..ed6c55c87fdc 100644 > > > --- a/arch/arm64/mm/fault.c > > > +++ b/arch/arm64/mm/fault.c > > > @@ -777,6 +777,42 @@ void __init hook_debug_fault_code(int nr, > > > debug_fault_info[nr].name = name; > > > } > > > > > > +/* > > > + * In debug exception context, we explicitly disable preemption. > > > > Maybe add "despite having interrupts disabled"? > > OK, I'll add it. > > > > + * This serves two purposes: it makes it much less likely that we would > > > + * accidentally schedule in exception context and it will force a warning > > > + * if we somehow manage to schedule by accident. > > > + */ > > > +static void debug_exception_enter(struct pt_regs *regs) > > > +{ > > > + if (user_mode(regs)) { > > > + RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); > > > + } else { > > > + /* > > > + * We might have interrupted pretty much anything. In > > > + * fact, if we're a debug exception, we can even interrupt > > > + * NMI processing. We don't want this code makes in_nmi() > > > + * to return true, but we need to notify RCU. > > > + */ > > > + rcu_nmi_enter(); > > > + } > > > + > > > + preempt_disable(); > > > > If you're addingt new functions for entry/exit, maybe move the > > trace_hardirqs_{on,off}() calls in here too? > > OK, let's move it in these functions.
Brill, thanks. Please just resend this patch, as I can pick the other three up as they are.
Will
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