linux-kernel - Re: [PATCH v6 02/11] locking/osq: Drop the overload of osq

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Date:   Sat, 29 Oct 2016 09:52:16 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        virtualization@...ts.linux-foundation.org,
        linux-s390@...r.kernel.org, xen-devel-request@...ts.xenproject.org,
        kvm@...r.kernel.org, xen-devel@...ts.xenproject.org,
        x86@...nel.org, benh@...nel.crashing.org, paulus@...ba.org,
        mpe@...erman.id.au, mingo@...hat.com, peterz@...radead.org,
        paulmck@...ux.vnet.ibm.com, will.deacon@....com,
        kernellwp@...il.com, jgross@...e.com, pbonzini@...hat.com,
        bsingharora@...il.com, boqun.feng@...il.com,
        borntraeger@...ibm.com, rkrcmar@...hat.com, David.Laight@...LAB.COM
Subject: Re: [PATCH v6 02/11] locking/osq: Drop the overload of osq_lock()

On Fri, 28 Oct 2016, Pan Xinhui wrote:
> 		/*
> 		 * If we need to reschedule bail... so we can block.
>+		 * Use vcpu_is_preempted to detech lock holder preemption issue
                                            ^^ detect
>+		 * and break. 

Could you please remove the rest of this comment? Its just noise to point out
that vcpu_is_preempted is a macro defined by arch/false. This is standard protocol
in the kernel.

Same goes for all locks you change with this.

Thanks,
Davidlohr

>                * vcpu_is_preempted is a macro defined by false if
>+		 * arch does not support vcpu preempted check,
> 		 */
>-		if (need_resched())
>+		if (need_resched() || vcpu_is_preempted(node_cpu(node->prev)))
> 			goto unqueue;
>
> 		cpu_relax_lowlatency();
>-- 
>2.4.11
>