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From: Thomas Gleixner <tglx@linutronix.de>
To: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	Michael Ellerman <mpe@ellerman.id.au>,
	Daniel Black <daniel.black@au1.ibm.com>
Subject: Re: [PATCH] powerpc: Drop lockdep_assert_cpus_held call from arch_update_cpu_topology
Date: Thu, 5 Oct 2017 14:38:55 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.20.1710051435530.2083@nanos> (raw)
In-Reply-To: <20171005000430.8080-1-bauerman@linux.vnet.ibm.com>

On Wed, 4 Oct 2017, Thiago Jung Bauermann wrote:

> It turns out that not all paths calling arch_update_cpu_topology hold
> cpu_hotplug_lock, but that's ok because those paths aren't supposed to race
> with any concurrent hotplug events.
> 
> Callers of arch_update_cpu_topology are expected to know what they are
> doing when they call the function without holding the lock, so remove the
> lockdep warning.

"Expected to know what they are doing" is not really a good approach as
it's way too simple to screw things up.

You might consider to have two functions where one does the check and the
other does not, but I leave that to the PPC maintainers.

Thanks,

	tglx

  reply	other threads:[~2017-10-05 12:39 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-05  0:04 [PATCH] powerpc: Drop lockdep_assert_cpus_held call from arch_update_cpu_topology Thiago Jung Bauermann
2017-10-05 12:38 ` Thomas Gleixner [this message]
2017-10-05 18:26   ` Thiago Jung Bauermann
2017-10-05 18:46     ` Thomas Gleixner
2017-10-10  9:48       ` Michael Ellerman
2017-10-12  0:20 ` Michael Ellerman

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