linux-kernel - RE: [PATCH v2] locking/rtmutex: Fix incorrect spinning condition

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Date:   Sat, 18 Dec 2021 10:34:56 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Zhang, Qiang1" <qiang1.zhang@...el.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "will@...nel.org" <will@...nel.org>,
        "longman@...hat.com" <longman@...hat.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Zhang, Qiang1" <qiang1.zhang@...el.com>
Subject: RE: [PATCH v2] locking/rtmutex: Fix incorrect spinning condition

On Sat, Dec 18 2021 at 07:24, Qiang1 Zhang wrote:
> -----Original Message-----
> From: Thomas Gleixner <tglx@...utronix.de> 
> Sent: 2021年12月18日 4:53
> To: Zhang, Qiang1 <qiang1.zhang@...el.com>; peterz@...radead.org; mingo@...hat.com; will@...nel.org; longman@...hat.com
> Cc: linux-kernel@...r.kernel.org; Zhang, Qiang1 <qiang1.zhang@...el.com>
> Subject: Re: [PATCH v2] locking/rtmutex: Fix incorrect spinning
> condition

Can you please fix your mail client to do proper replies without copying
the mail headers into the message?

>>Though this does not apply because the condition is incomplete. You
>>somehow dropped this from the condition:
>>
>>                   vcpu_is_preempted(task_cpu(owner))) 
>>
>>Please make always sure that your patches apply against Linus tree
>>before sending them out.
>
> This commit c0bed69daf4b ("locking: Make owner_on_cpu() into <linux/sched.h>")
> make the following modifications in latest linux-next.
>
> +static inline bool owner_on_cpu(struct task_struct *owner)
> +{
> +       /*
> +        * As lock holder preemption issue, we both skip spinning if
> +        * task is not on cpu or its cpu is preempted
> +        */
> +       return owner->on_cpu && !vcpu_is_preempted(task_cpu(owner));
> +}
> +

Fine, but then please tell against which tree/branch the patch is.

Thanks,

        tglx