Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c

From	Juergen Gross <jgross@suse.com>
Newsgroups	linux.kernel
Subject	Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c
Date	2017-07-07 17:00 +0200
Message-ID	<u0CTE-5qc-9@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Commit bf22ff45bed664aefb5c4e43029057a199b7070c ("genirq: Avoid
unnecessary low level irq function calls") breaks Xen guest
save/restore handling.

The main problem are the PV devices using Xen event channels as
interrupt sources which are represented as an "irq chip" in the kernel.
When saving the guest the event channels are masked internally. At
restore time event channels are re-established and unmasked via
irq_startup(). Unfortunately above commit will let the unmask operation
be a nop as the irq handling doesn't know about the masking done before.

I have a patch repairing the issue, but I'm not sure if this way to do
it would be accepted. I have exported mask_irq() and I'm doing the
masking now through this function. Would the attached patch be
acceptable? Or is there a better way to solve the problem?


Juergen

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Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c Juergen Gross <jgross@suse.com> - 2017-07-07 17:00 +0200
  Re: Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c Thomas Gleixner <tglx@linutronix.de> - 2017-07-07 18:50 +0200
    Re: Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c Juergen Gross <jgross@suse.com> - 2017-07-07 19:10 +0200
    Re: Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c Thomas Gleixner <tglx@linutronix.de> - 2017-07-07 19:20 +0200
      Re: Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c Juergen Gross <jgross@suse.com> - 2017-07-10 09:30 +0200
        Re: Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c Thomas Gleixner <tglx@linutronix.de> - 2017-07-12 17:40 +0200
          Re: Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c Thomas Gleixner <tglx@linutronix.de> - 2017-07-12 22:30 +0200
  Re: Problem with commit bf22ff45bed664aefb5c4e43029057a199b7070c Marc Zyngier <marc.zyngier@arm.com> - 2017-07-07 19:20 +0200

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