From: Michael Ellerman <mpe@ellerman.id.au>
To: Cyril Bur <cyrilbur@gmail.com>, linuxppc-dev@ozlabs.org
Subject: Re: [v2] powerpc: Fix checkstop in native_hpte_clear() with lockdep
Date: Tue, 13 Oct 2015 14:47:15 +1100 (AEDT) [thread overview]
Message-ID: <20151013034715.43765140FDB@ozlabs.org> (raw)
In-Reply-To: <1444262666-6942-1-git-send-email-cyrilbur@gmail.com>
On Thu, 2015-08-10 at 00:04:26 UTC, Cyril Bur wrote:
> native_hpte_clear() is called in real mode from two places:
> - Early in boot during htab initialisation if firmware assisted dump is
> active.
> - Late in the kexec path.
>
> In both contexts there is no need to disable interrupts are they are
> already disabled. Furthermore, locking around the tlbie() is only required
> for pre POWER5 hardware.
>
> On POWER5 or newer hardware concurrent tlbie()s work as expected and on pre
> POWER5 hardware concurrent tlbie()s could result in deadlock. This code
> would only be executed at crashdump time, during which all bets are off,
> concurrent tlbie()s are unlikely and taking locks is unsafe therefore the
> best course of action is to simply do nothing. Concurrent tlbie()s are not
> possible in the first case as secondary CPUs have not come up yet.
>
> Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/fdf880a60835cd1dec256346
cheers
prev parent reply other threads:[~2015-10-13 3:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-08 0:04 [PATCH v2] powerpc: Fix checkstop in native_hpte_clear() with lockdep Cyril Bur
2015-10-13 3:47 ` Michael Ellerman [this message]
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