linux-kernel - Re: [PATCH -tip 23/32] sched: Add a per-thread core scheduling interface

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Message-ID: <485a1db3-dc92-de37-e915-a4dd427b74d3@oracle.com>
Date:   Wed, 2 Dec 2020 18:13:07 -0500
From:   chris hyser <chris.hyser@...cle.com>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.intel@...il.com>, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, mingo@...nel.org,
        torvalds@...ux-foundation.org, fweisbec@...il.com,
        keescook@...omium.org, kerrnel@...gle.com,
        Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>, vineeth@...byteword.org,
        Chen Yu <yu.c.chen@...el.com>,
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        Dhaval Giani <dhaval.giani@...cle.com>,
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        Ben Segall <bsegall@...gle.com>, Josh Don <joshdon@...gle.com>,
        Hao Luo <haoluo@...gle.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Tim Chen <tim.c.chen@...el.com>
Subject: Re: [PATCH -tip 23/32] sched: Add a per-thread core scheduling
 interface

On 12/2/20 4:47 PM, Chris Hyser wrote:

> +	get_task_struct(task);
> +
> +	/*
> +	 * Check if this process has the right to modify the specified
> +	 * process. Use the regular "ptrace_may_access()" checks.
> +	 */
> +	if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
> +		rcu_read_unlock();
> +		err = -EPERM;
> +		goto out;
> +	}
> +	rcu_read_unlock();
> +
> +	if (flags == PR_SCHED_CORE_CLEAR) {
> +		dest = task;
> +		src = NULL;
> +	} else if (flags == PR_SCHED_CORE_SHARE_TO) {
> +		dest = task;
> +		src = current;
> +	} else if (flags == PR_SCHED_CORE_SHARE_FROM) {
> +		dest = current;
> +		src = task;
> +	}

I should have put in an else clause to catch bad input.

> +
> +	err = sched_core_share_tasks(dest, src);
>   out:
>   	if (task)
>   		put_task_struct(task);