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From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Ben Skeggs <bskeggs@redhat.com>,
	Mike Galbraith <efault@gmx.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH 1/2] kthread: Move prio/affinite change into the newly created thread
Date: Sat, 21 Nov 2020 11:55:48 +0100	[thread overview]
Message-ID: <87a6vbnfm3.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201117124503.GI3121406@hirez.programming.kicks-ass.net>

On Tue, Nov 17 2020 at 13:45, Peter Zijlstra wrote:
> On Tue, Nov 10, 2020 at 12:38:47PM +0100, Sebastian Andrzej Siewior wrote:
>
> Moo... yes this is certainly the easiest solution, because nouveau is a
> horrible rats nest. But when I spoke to Greg KH about this, he suggested
> nouveau ought to be fixed.
>
> Ben, I got terminally lost when trying to untangle nouvea init, is there
> any chance this can be fixed to not hold that nvkm_device::mutex thing
> while doing request_irq() ?

OTOH, creating a dependency chain vs. cpuset_rwsem and whatever lock is
held by the caller via request_irq() or kthread_create() is not
necessarily restricted to the nivea driver. struct device::mutex (not
the nkvm_device::mutex) is always held when a driver is probed.

The cpuset_rwsem -> mmap_lock dependency is a given, so we're one step
away from a circular dependency vs. mmap_lock.

That was my reasoning to move the stuff out into the thread context.

Thanks,

        tglx




  parent reply	other threads:[~2020-11-21 10:57 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-10 11:38 [PATCH 0/2] genirq: Move prio assignment " Sebastian Andrzej Siewior
2020-11-10 11:38 ` [PATCH 1/2] kthread: Move prio/affinite change " Sebastian Andrzej Siewior
2020-11-17 12:45   ` Peter Zijlstra
2020-11-20 22:17     ` Sebastian Andrzej Siewior
2020-11-21 10:55     ` Thomas Gleixner [this message]
2021-03-03 16:25       ` Sebastian Andrzej Siewior
2020-11-10 11:38 ` [PATCH 2/2] genirq: Move prio assignment " Sebastian Andrzej Siewior

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