Re: [PATCH] synchronize_irq needs a barrier

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To: Maxim Levitsky <maximlevitsky@...>

Cc: Linus Torvalds <torvalds@...>, akpm <akpm@...>, Linux Kernel list <linux-kernel@...>, linuxppc-dev list <linuxppc-dev@...>

Subject: Re: [PATCH] synchronize_irq needs a barrier

Date: Saturday, October 20, 2007 - 12:06 am

> >  - even when you ignore the interrupt (because the driver doesn't care, 
quoted text> >    it's suspending), you need to make sure the hardware gets shut up by 
> >    reading (or writing) the proper interrupt status register.
> I agree, but while device is powered off, its registers can't be accessed
> Thus, if I ack the IRQ every time the handler is called, I will access the 
> powered off device (this is probably won't hurt a lot, but a bit incorrectly)

It will actually crash your machine on some platforms. So no, best is to
-not- ack. The masking is enough, the IRQ will go down eventually.

Ben.


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Messages in current thread:

[PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Wed Oct 17, 9:25 pm)

Re: [PATCH] synchronize_irq needs a barrier, Maxim Levitsky, (Fri Oct 19, 10:02 pm)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Fri Oct 19, 11:56 pm)

Re: [PATCH] synchronize_irq needs a barrier, Maxim Levitsky, (Sat Oct 20, 12:24 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Sat Oct 20, 1:04 am)

Re: [PATCH] synchronize_irq needs a barrier, Maxim Levitsky, (Sat Oct 20, 1:36 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Sat Oct 20, 1:46 am)

Re: [PATCH] synchronize_irq needs a barrier, Maxim Levitsky, (Sat Oct 20, 2:06 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Sat Oct 20, 2:13 am)

Re: [PATCH] synchronize_irq needs a barrier, Herbert Xu, (Fri Oct 19, 11:37 pm)

Re: [PATCH] synchronize_irq needs a barrier, Linus Torvalds, (Fri Oct 19, 10:25 pm)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Sat Oct 20, 12:04 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Sat Oct 20, 12:09 am)

Re: [PATCH] synchronize_irq needs a barrier, Maxim Levitsky, (Fri Oct 19, 11:10 pm)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Sat Oct 20, 12:06 am)

Re: [PATCH] synchronize_irq needs a barrier, Linus Torvalds, (Wed Oct 17, 10:12 pm)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Wed Oct 17, 10:40 pm)

Re: [PATCH] synchronize_irq needs a barrier, Herbert Xu, (Thu Oct 18, 10:35 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Thu Oct 18, 5:35 pm)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Wed Oct 17, 10:57 pm)

Re: [PATCH] synchronize_irq needs a barrier, Herbert Xu, (Thu Oct 18, 10:56 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Thu Oct 18, 6:05 pm)

Re: [PATCH] synchronize_irq needs a barrier, Linus Torvalds, (Thu Oct 18, 6:52 pm)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Thu Oct 18, 7:17 pm)

Re: [PATCH] synchronize_irq needs a barrier, Linus Torvalds, (Thu Oct 18, 7:39 pm)

Re: [PATCH] synchronize_irq needs a barrier, Herbert Xu, (Thu Oct 18, 10:32 pm)

Re: [PATCH] synchronize_irq needs a barrier, Linus Torvalds, (Thu Oct 18, 10:55 pm)

Re: [PATCH] synchronize_irq needs a barrier, Linus Torvalds, (Thu Oct 18, 11:26 pm)

Re: [PATCH] synchronize_irq needs a barrier, Herbert Xu, (Fri Oct 19, 12:20 am)

[NET]: Fix possible dev_deactivate race condition, Herbert Xu, (Fri Oct 19, 1:36 am)

Re: [NET]: Fix possible dev_deactivate race condition, Peter Zijlstra, (Fri Oct 19, 3:35 am)

Re: [NET]: Fix possible dev_deactivate race condition, Herbert Xu, (Fri Oct 19, 5:29 am)

Re: [NET]: Fix possible dev_deactivate race condition, David Miller, (Fri Oct 19, 1:38 am)

Re: [PATCH] synchronize_irq needs a barrier, Herbert Xu, (Fri Oct 19, 12:48 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Fri Oct 19, 12:58 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Sun Oct 21, 5:10 pm)

[IRQ]: Fix synchronize_irq races with IRQ handler, Herbert Xu, (Mon Oct 22, 11:26 pm)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Fri Oct 19, 12:35 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Fri Oct 19, 12:29 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Fri Oct 19, 12:11 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Fri Oct 19, 12:26 am)

Re: [PATCH] synchronize_irq needs a barrier, Herbert Xu, (Fri Oct 19, 1:53 am)

Re: [PATCH] synchronize_irq needs a barrier, Nick Piggin, (Thu Oct 18, 10:52 pm)

Re: [PATCH] synchronize_irq needs a barrier, Herbert Xu, (Thu Oct 18, 11:28 pm)

Re: [PATCH] synchronize_irq needs a barrier, Nick Piggin, (Fri Oct 19, 12:49 am)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Thu Oct 18, 7:52 pm)

Re: [PATCH] synchronize_irq needs a barrier, Andrew Morton, (Wed Oct 17, 9:45 pm)

Re: [PATCH] synchronize_irq needs a barrier, Benjamin Herrenschmidt, (Wed Oct 17, 9:55 pm)

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