linux-kernel - Re: [PATCH v2 2/3] locking/rwsem: disable preemption for spinning region

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Message-ID: <41448d61-8711-15b7-c120-7ce27e47134a@windriver.com>
Date:   Fri, 15 Oct 2021 20:33:20 +0800
From:   "Xu, Yanfei" <yanfei.xu@...driver.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     mingo@...hat.com, will@...nel.org, longman@...hat.com,
        boqun.feng@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] locking/rwsem: disable preemption for spinning
 region



On 10/15/21 6:20 PM, Peter Zijlstra wrote:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
> 
> On Fri, Oct 15, 2021 at 12:13:59PM +0200, Peter Zijlstra wrote:
>> On Wed, Oct 13, 2021 at 09:41:53PM +0800, Yanfei Xu wrote:
>>> The spinning region rwsem_spin_on_owner() should not be preempted,
>>> however the rwsem_down_write_slowpath() invokes it and don't disable
>>> preemption. Fix it by adding a pair of preempt_disable/enable().
>>
>> I'm thinking we should do this patch before #1, otherwise we have a
>> single patch window where we'll trigger the assertion, no?
> 
> Anyway, I've stuck the lot (reordered) into my locking/core branch, lets
> see what the robots make of it ;-)
> 
Well, thanks for reordering them :)

Cheers,
Yanfei