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Date:   Mon, 17 Jan 2022 13:22:30 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Peter Oskolkov <posk@posk.io>
Cc:     mingo@redhat.com, tglx@linutronix.de, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-api@vger.kernel.org, x86@kernel.org,
        pjt@google.com, posk@google.com, avagin@google.com,
        jannh@google.com, tdelisle@uwaterloo.ca
Subject: Re: [RFC][PATCH 3/3] sched: User Mode Concurency Groups
Message-ID: <YeVfhi3bXzgYBdf3@hirez.programming.kicks-ass.net>
References: <20211214204445.665580974@infradead.org>
 <20211214205358.701701555@infradead.org>
 <20211221171900.GA580323@dev-hv>
 <YeGEM7TP3tekBVEh@hirez.programming.kicks-ass.net>
 <YeVUgXd6C85VmaP7@hirez.programming.kicks-ass.net>
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Precedence: bulk

On Mon, Jan 17, 2022 at 12:35:29PM +0100, Peter Zijlstra wrote:
> @@ -794,16 +798,31 @@ SYSCALL_DEFINE3(umcg_ctl, u32, flags, st
>  		      UMCG_CTL_WORKER))
>  		return -EINVAL;
>  
> -	if (flags == UMCG_CTL_UNREGISTER) {
> -		if (self || !current->umcg_task)
> +	if (flags & UMCG_CTL_UNREGISTER) {
> +		int ret;
> +
> +		if (!self || self != current->umcg_task)
>  			return -EINVAL;
>  
> -		if (current->flags & PF_UMCG_WORKER) {
> -			umcg_worker_exit();
> -			// XXX wake server
> -		} else
> -			umcg_clear_task(current);
> +		current->flags &= ~PF_UMCG_WORKER;
>  
> +		ret = umcg_pin_pages();
> +		if (ret) {
> +			current->flags |= PF_UMCG_WORKER;
> +			return ret;
> +		}
> +
> +		ret = umcg_update_state(current, self, UMCG_TASK_RUNNING, UMCG_TASK_NONE);
> +		if (ret) {
> +			current->flags |= PF_UMCG_WORKER;
> +			return ret;
> +		}

Sorry, should obv only restore PF_UMCG_WORKER for workers.. /me fixes

> +
> +		if (current->flags & PF_UMCG_WORKER)
> +			umcg_wake(current);
> +
> +		umcg_unpin_pages();
> +		umcg_clear_task(current);
>  		return 0;
>  	}
>