Messages in this thread | | | Date | Tue, 15 Jun 2010 13:51:55 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v5 7/14] x86 support for Uprobes |
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On 06/15, Srikar Dronamraju wrote: > > * Christoph Hellwig <hch@infradead.org> [2010-06-14 13:54:23]: > > > On Mon, Jun 14, 2010 at 01:59:13PM +0530, Srikar Dronamraju wrote: > > > @@ -850,7 +850,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) > > > > > > if (thread_info_flags & _TIF_UPROBE) { > > > clear_thread_flag(TIF_UPROBE); > > > +#ifdef CONFIG_X86_32 > > > + /* > > > + * On x86_32, do_notify_resume() gets called with > > > + * interrupts disabled. Hence enable interrupts if they > > > + * are still disabled. > > > + */ > > > + native_irq_enable(); > > > +#endif > > > uprobe_notify_resume(regs); > > > + > > > +#ifdef CONFIG_X86_32 > > > + native_irq_disable(); > > > +#endif > > > > I'm no x86 port guru, but this looks rather worriesome to me. Why does > > do_notify_resume have different calling conventions on 32 vs 64-bit? > > And if there is a good reason that 32-bit has them disabled, why is > > enabling them in the middle of do_notify_resume okay? > > Thanks for bringing this up. I have no idea about why do_notify_resume() > gets called with interrupts disabled in 32 bit.
Perhaps just because there is no reason to explicitly enable irqs?
> I would be happy to know > the reason and rework based on inputs. I did query a few people about > this but I havent got an answer on why we they are disabled on 32 bit and > if its Okay to enable at this place.
I think it is OK to enable interrupts. do_notify_resume() calls do_signal() which enables them anyway.
But there is another question I already asked. Why the code uses native_irq_enable()? IIRC, you explained that local_irq_enable() doesn't work for unkown reason. This is strange, and imho should be explained.
And I do not see a need to disable irqs again.
Oleg.
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