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Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is patching the handler

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On Fri, 4 Sep 2015, Borislav Petkov wrote:
> On Thu, Sep 03, 2015 at 12:41:47PM +0200, Thomas Gleixner wrote:
> > Nah. I rather put the local_irq_save into optimize_nops(). All other
> > callers of add_nops() are operating on a buffer and use text_poke
> > after that. Aside of that optimize_nops() is missing a sync_core().
> 
> Whoops.
> 
> > Updated patch below.
> 
> Looks good, thanks.
> 
> Hrrm, maybe optimize_nops() should work on a buffer and do
> text_poke_early() too at the end, so that it doesn't differ from all the
> other paths changing kernel text. So as to stuff like that doesn't get
> missed next time I'm touching it.
> 
> But with your way we don't need the additional buffer. I guess your
> solution is better resource-wise.

I pondered the buffer/text_poke variant, but that's too much of a
hassle for a fix supposed to go to stable.

Resourcewise you could use the buffer which is available in
apply_alternatives anyway.

Thanks,

	tglx
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[BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Chuck Ebbert <cebbert.lkml@gmail.com> - 2015-08-31 04:40 +0200
  Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler "Richard W.M. Jones" <rjones@redhat.com> - 2015-09-01 08:30 +0200
    Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Thomas Gleixner <tglx@linutronix.de> - 2015-09-02 11:20 +0200
      Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler "Richard W.M. Jones" <rjones@redhat.com> - 2015-09-02 21:10 +0200
        Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler "Richard W.M. Jones" <rjones@redhat.com> - 2015-09-03 10:00 +0200
      Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Borislav Petkov <bp@alien8.de> - 2015-09-03 11:00 +0200
        Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Thomas Gleixner <tglx@linutronix.de> - 2015-09-03 12:50 +0200
          Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Josh Boyer <jwboyer@fedoraproject.org> - 2015-09-03 14:50 +0200
            Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Thomas Gleixner <tglx@linutronix.de> - 2015-09-03 15:10 +0200
          Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler "Richard W.M. Jones" <rjones@redhat.com> - 2015-09-03 18:00 +0200
          [tip:x86/urgent] x86/alternatives: Make optimize_nops()   interrupt safe and synced tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2015-09-03 21:40 +0200
          Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler "Richard W.M. Jones" <rjones@redhat.com> - 2015-09-04 09:50 +0200
          Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Borislav Petkov <bp@alien8.de> - 2015-09-04 14:10 +0200
            Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Thomas Gleixner <tglx@linutronix.de> - 2015-09-04 15:40 +0200
              Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is  patching the handler Borislav Petkov <bp@alien8.de> - 2015-09-05 17:30 +0200

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