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From: Qais Yousef <qais.yousef@arm.com>
To: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Quentin Perret <qperret@google.com>, Tejun Heo <tj@kernel.org>,
	Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	kernel-team@android.com
Subject: Re: [PATCH v6 11/21] sched: Split the guts of sched_setaffinity() into a helper function
Date: Fri, 21 May 2021 17:41:01 +0100	[thread overview]
Message-ID: <20210521164101.lwq5wr4mbb32co6l@e107158-lin.cambridge.arm.com> (raw)
In-Reply-To: <20210518094725.7701-12-will@kernel.org>

On 05/18/21 10:47, Will Deacon wrote:
> In preparation for replaying user affinity requests using a saved mask,
> split sched_setaffinity() up so that the initial task lookup and
> security checks are only performed when the request is coming directly
> from userspace.
> 
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  kernel/sched/core.c | 110 +++++++++++++++++++++++---------------------
>  1 file changed, 58 insertions(+), 52 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 9512623d5a60..808bbe669a6d 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -6788,9 +6788,61 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
>  	return retval;
>  }
>  
> -long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
> +static int
> +__sched_setaffinity(struct task_struct *p, const struct cpumask *mask)
>  {
> +	int retval;
>  	cpumask_var_t cpus_allowed, new_mask;
> +
> +	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL))
> +		return -ENOMEM;
> +
> +	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
> +		return -ENOMEM;

Shouldn't we free cpus_allowed first?

Cheers

--
Qais Yousef

> +
> +	cpuset_cpus_allowed(p, cpus_allowed);
> +	cpumask_and(new_mask, mask, cpus_allowed);
> +
> +	/*
> +	 * Since bandwidth control happens on root_domain basis,
> +	 * if admission test is enabled, we only admit -deadline
> +	 * tasks allowed to run on all the CPUs in the task's
> +	 * root_domain.
> +	 */
> +#ifdef CONFIG_SMP
> +	if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
> +		rcu_read_lock();
> +		if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
> +			retval = -EBUSY;
> +			rcu_read_unlock();
> +			goto out_free_masks;
> +		}
> +		rcu_read_unlock();
> +	}
> +#endif
> +again:
> +	retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK);
> +	if (retval)
> +		goto out_free_masks;
> +
> +	cpuset_cpus_allowed(p, cpus_allowed);
> +	if (!cpumask_subset(new_mask, cpus_allowed)) {
> +		/*
> +		 * We must have raced with a concurrent cpuset update.
> +		 * Just reset the cpumask to the cpuset's cpus_allowed.
> +		 */
> +		cpumask_copy(new_mask, cpus_allowed);
> +		goto again;
> +	}
> +
> +out_free_masks:
> +	free_cpumask_var(new_mask);
> +	free_cpumask_var(cpus_allowed);
> +	return retval;
> +}
> +
> +long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
> +{
>  	struct task_struct *p;
>  	int retval;
>  
> @@ -6810,68 +6862,22 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
>  		retval = -EINVAL;
>  		goto out_put_task;
>  	}
> -	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
> -		retval = -ENOMEM;
> -		goto out_put_task;
> -	}
> -	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
> -		retval = -ENOMEM;
> -		goto out_free_cpus_allowed;
> -	}
> -	retval = -EPERM;
> +
>  	if (!check_same_owner(p)) {
>  		rcu_read_lock();
>  		if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
>  			rcu_read_unlock();
> -			goto out_free_new_mask;
> +			retval = -EPERM;
> +			goto out_put_task;
>  		}
>  		rcu_read_unlock();
>  	}
>  
>  	retval = security_task_setscheduler(p);
>  	if (retval)
> -		goto out_free_new_mask;
> -
> -
> -	cpuset_cpus_allowed(p, cpus_allowed);
> -	cpumask_and(new_mask, in_mask, cpus_allowed);
> -
> -	/*
> -	 * Since bandwidth control happens on root_domain basis,
> -	 * if admission test is enabled, we only admit -deadline
> -	 * tasks allowed to run on all the CPUs in the task's
> -	 * root_domain.
> -	 */
> -#ifdef CONFIG_SMP
> -	if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
> -		rcu_read_lock();
> -		if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
> -			retval = -EBUSY;
> -			rcu_read_unlock();
> -			goto out_free_new_mask;
> -		}
> -		rcu_read_unlock();
> -	}
> -#endif
> -again:
> -	retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK);
> +		goto out_put_task;
>  
> -	if (!retval) {
> -		cpuset_cpus_allowed(p, cpus_allowed);
> -		if (!cpumask_subset(new_mask, cpus_allowed)) {
> -			/*
> -			 * We must have raced with a concurrent cpuset
> -			 * update. Just reset the cpus_allowed to the
> -			 * cpuset's cpus_allowed
> -			 */
> -			cpumask_copy(new_mask, cpus_allowed);
> -			goto again;
> -		}
> -	}
> -out_free_new_mask:
> -	free_cpumask_var(new_mask);
> -out_free_cpus_allowed:
> -	free_cpumask_var(cpus_allowed);
> +	retval = __sched_setaffinity(p, in_mask);
>  out_put_task:
>  	put_task_struct(p);
>  	return retval;
> -- 
> 2.31.1.751.gd2f1c929bd-goog
> 

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  reply	other threads:[~2021-05-21 16:42 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-18  9:47 [PATCH v6 00/21] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-05-18  9:47 ` [PATCH v6 01/21] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon
2021-05-21 10:47   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 02/21] arm64: Allow mismatched 32-bit EL0 support Will Deacon
2021-05-21 10:25   ` Catalin Marinas
2021-05-24 12:05     ` Will Deacon
2021-05-24 13:49       ` Catalin Marinas
2021-05-21 10:41   ` Catalin Marinas
2021-05-24 12:09     ` Will Deacon
2021-05-24 13:46       ` Catalin Marinas
2021-05-21 15:22   ` Qais Yousef
2021-05-24 20:21     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 03/21] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon
2021-05-21 10:47   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 04/21] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Will Deacon
2021-05-21 10:55   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 05/21] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2021-05-21 11:00   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 06/21] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2021-05-21 16:03   ` Peter Zijlstra
2021-05-24 12:17     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 07/21] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2021-05-21 17:39   ` Qais Yousef
2021-05-24 20:21     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 08/21] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Will Deacon
2021-05-21 16:25   ` Qais Yousef
2021-05-24 21:09     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 09/21] sched: Reject CPU affinity changes based on task_cpu_possible_mask() Will Deacon
2021-05-18  9:47 ` [PATCH v6 10/21] sched: Introduce task_struct::user_cpus_ptr to track requested affinity Will Deacon
2021-05-18  9:47 ` [PATCH v6 11/21] sched: Split the guts of sched_setaffinity() into a helper function Will Deacon
2021-05-21 16:41   ` Qais Yousef [this message]
2021-05-24 21:16     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 12/21] sched: Allow task CPU affinity to be restricted on asymmetric systems Will Deacon
2021-05-21 17:11   ` Qais Yousef
2021-05-24 21:43     ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 13/21] sched: Admit forcefully-affined tasks into SCHED_DEADLINE Will Deacon
2021-05-18 10:20   ` Quentin Perret
2021-05-18 10:28     ` Will Deacon
2021-05-18 10:48       ` Quentin Perret
2021-05-18 10:59         ` Will Deacon
2021-05-18 13:19           ` Quentin Perret
2021-05-20  9:13             ` Juri Lelli
2021-05-20 10:16               ` Will Deacon
2021-05-20 10:33                 ` Quentin Perret
2021-05-20 12:38                   ` Juri Lelli
2021-05-20 12:38                   ` Daniel Bristot de Oliveira
2021-05-20 15:06                     ` Dietmar Eggemann
2021-05-20 16:00                       ` Daniel Bristot de Oliveira
2021-05-20 17:55                         ` Dietmar Eggemann
2021-05-20 18:03                           ` Will Deacon
2021-05-21 11:26                             ` Dietmar Eggemann
2021-05-20 18:01                     ` Will Deacon
2021-05-21  5:25                       ` Juri Lelli
2021-05-21  8:15                         ` Quentin Perret
2021-05-21  8:39                           ` Juri Lelli
2021-05-21 10:37                             ` Will Deacon
2021-05-21 11:23                               ` Dietmar Eggemann
2021-05-21 13:02                                 ` Quentin Perret
2021-05-21 14:04                                   ` Juri Lelli
2021-05-21 17:47                                     ` Dietmar Eggemann
2021-05-21 13:00                               ` Daniel Bristot de Oliveira
2021-05-21 13:12                                 ` Quentin Perret
2021-05-24 20:47                                 ` Will Deacon
2021-05-18  9:47 ` [PATCH v6 14/21] freezer: Add frozen_or_skipped() helper function Will Deacon
2021-05-18  9:47 ` [PATCH v6 15/21] sched: Defer wakeup in ttwu() for unschedulable frozen tasks Will Deacon
2021-05-18  9:47 ` [PATCH v6 16/21] arm64: Implement task_cpu_possible_mask() Will Deacon
2021-05-24 14:57   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 17/21] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2021-05-24 15:02   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 18/21] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2021-05-24 15:46   ` Catalin Marinas
2021-05-24 20:32     ` Will Deacon
2021-05-25  9:43       ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 19/21] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2021-05-24 15:47   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 20/21] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2021-05-24 15:47   ` Catalin Marinas
2021-05-18  9:47 ` [PATCH v6 21/21] Documentation: arm64: describe asymmetric 32-bit support Will Deacon
2021-05-21 17:37   ` Qais Yousef
2021-05-24 21:46     ` Will Deacon
2021-05-24 16:22   ` Catalin Marinas
2021-05-21 17:45 ` [PATCH v6 00/21] Add support for 32-bit tasks on asymmetric AArch32 systems Qais Yousef
2021-05-24 22:08   ` Will Deacon

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