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From: Thomas Gleixner <tglx@linutronix.de>
To: Borislav Petkov <bp@alien8.de>
Cc: "Richard W.M. Jones" <rjones@redhat.com>,
	Chuck Ebbert <cebbert.lkml@gmail.com>,
	linux-kernel@vger.kernel.org, x86@kernel.org,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is patching the handler
Date: Fri, 4 Sep 2015 15:37:24 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.11.1509041536120.15006@nanos> (raw)
In-Reply-To: <20150904120238.GB23550@nazgul.tnic>

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

  reply	other threads:[~2015-09-04 13:38 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-31  2:37 [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is patching the handler Chuck Ebbert
2015-09-01  6:20 ` Richard W.M. Jones
2015-09-02  9:11   ` Thomas Gleixner
2015-09-02 19:05     ` Richard W.M. Jones
2015-09-03  7:53       ` Richard W.M. Jones
2015-09-03  8:50     ` Borislav Petkov
2015-09-03 10:41       ` Thomas Gleixner
2015-09-03 12:43         ` Josh Boyer
2015-09-03 13:01           ` Thomas Gleixner
2015-09-03 15:48         ` Richard W.M. Jones
2015-09-03 19:30         ` [tip:x86/urgent] x86/alternatives: Make optimize_nops() interrupt safe and synced tip-bot for Thomas Gleixner
2015-09-04  7:40         ` [BUG 4.2-rc8] Interrupt occurs while apply_alternatives() is patching the handler Richard W.M. Jones
2015-09-04 12:02         ` Borislav Petkov
2015-09-04 13:37           ` Thomas Gleixner [this message]
2015-09-05 15:25             ` Borislav Petkov

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