From: Peter Zijlstra <peterz@infradead.org>
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>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Qais Yousef <qais.yousef@arm.com>,
Suren Baghdasaryan <surenb@google.com>,
Quentin Perret <qperret@google.com>, Tejun Heo <tj@kernel.org>,
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>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
kernel-team@android.com
Subject: Re: [PATCH v11 08/16] sched: Allow task CPU affinity to be restricted on asymmetric systems
Date: Wed, 18 Aug 2021 13:53:28 +0200 [thread overview]
Message-ID: <YRz0uI6V58eGNL1C@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YRznaZBHXYEzCPt1@hirez.programming.kicks-ass.net>
On Wed, Aug 18, 2021 at 12:56:41PM +0200, Peter Zijlstra wrote:
> On Wed, Aug 18, 2021 at 11:42:28AM +0100, Will Deacon wrote:
> > I think the idea looks good, but perhaps we could wrap things up a bit:
> >
> > /* Comment about why this is useful with RT */
> > static cpumask_t *clear_user_cpus_ptr(struct task_struct *p)
> > {
> > struct cpumask *user_mask = NULL;
> >
> > swap(user_mask, p->user_cpus_ptr);
> > return user_mask;
> > }
> >
> > void release_user_cpus_ptr(struct task_struct *p)
> > {
> > kfree(clear_user_cpus_ptr(p));
> > }
> >
> > Then just use clear_user_cpus_ptr() in sched/core.c where we know what
> > we're doing (well, at least one of us does!).
>
> OK, I'll go make it like that.
Something like so then?
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2497,10 +2497,18 @@ int dup_user_cpus_ptr(struct task_struct
return 0;
}
+static inline struct cpumask *clear_user_cpus_ptr(struct task_struct *p)
+{
+ struct cpumask *user_mask = NULL;
+
+ swap(p->user_cpus_ptr, user_mask);
+
+ return user_mask;
+}
+
void release_user_cpus_ptr(struct task_struct *p)
{
- kfree(p->user_cpus_ptr);
- p->user_cpus_ptr = NULL;
+ kfree(clear_user_cpus_ptr(p));
}
/*
@@ -2733,6 +2741,7 @@ static int __set_cpus_allowed_ptr_locked
const struct cpumask *cpu_allowed_mask = task_cpu_possible_mask(p);
const struct cpumask *cpu_valid_mask = cpu_active_mask;
bool kthread = p->flags & PF_KTHREAD;
+ struct cpumask *user_mask = NULL;
unsigned int dest_cpu;
int ret = 0;
@@ -2792,9 +2801,13 @@ static int __set_cpus_allowed_ptr_locked
__do_set_cpus_allowed(p, new_mask, flags);
if (flags & SCA_USER)
- release_user_cpus_ptr(p);
+ user_mask = clear_user_cpus_ptr(p);
- return affine_move_task(rq, p, rf, dest_cpu, flags);
+ ret = affine_move_task(rq, p, rf, dest_cpu, flags);
+
+ kfree(user_mask);
+
+ return ret;
out:
task_rq_unlock(rq, p, rf);
@@ -2941,20 +2954,22 @@ __sched_setaffinity(struct task_struct *
*/
void relax_compatible_cpus_allowed_ptr(struct task_struct *p)
{
+ struct cpumask *user_mask = p->user_cpus_ptr;
unsigned long flags;
- struct cpumask *mask = p->user_cpus_ptr;
/*
* Try to restore the old affinity mask. If this fails, then
* we free the mask explicitly to avoid it being inherited across
* a subsequent fork().
*/
- if (!mask || !__sched_setaffinity(p, mask))
+ if (!user_mask || !__sched_setaffinity(p, user_mask))
return;
raw_spin_lock_irqsave(&p->pi_lock, flags);
- release_user_cpus_ptr(p);
+ user_mask = clear_user_cpus_ptr(p);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
+ kfree(user_mask);
}
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
next prev parent reply other threads:[~2021-08-18 11:56 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 11:24 [PATCH v11 00/16] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-07-30 11:24 ` [PATCH v11 01/16] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 02/16] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 03/16] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 04/16] cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq() Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 05/16] sched: Reject CPU affinity changes based on task_cpu_possible_mask() Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 06/16] sched: Introduce task_struct::user_cpus_ptr to track requested affinity Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 07/16] sched: Split the guts of sched_setaffinity() into a helper function Will Deacon
2021-08-17 15:40 ` Peter Zijlstra
2021-08-18 10:50 ` Will Deacon
2021-08-18 10:56 ` Peter Zijlstra
2021-08-18 11:11 ` Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 08/16] sched: Allow task CPU affinity to be restricted on asymmetric systems Will Deacon
2021-08-17 15:10 ` Peter Zijlstra
2021-08-18 10:42 ` Will Deacon
2021-08-18 10:56 ` Peter Zijlstra
2021-08-18 11:53 ` Peter Zijlstra [this message]
2021-08-18 12:19 ` Will Deacon
2021-08-18 11:06 ` Peter Zijlstra
2021-08-17 15:41 ` Peter Zijlstra
2021-08-18 10:43 ` Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 09/16] sched: Introduce dl_task_check_affinity() to check proposed affinity Will Deacon
2021-08-23 9:26 ` [tip: sched/core] " tip-bot2 for Will Deacon
2021-07-30 11:24 ` [PATCH v11 10/16] arm64: Implement task_cpu_possible_mask() Will Deacon
2021-07-30 11:24 ` [PATCH v11 11/16] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2021-07-30 11:24 ` [PATCH v11 12/16] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2021-07-30 11:24 ` [PATCH v11 13/16] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2021-07-30 11:24 ` [PATCH v11 14/16] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2021-07-30 11:24 ` [PATCH v11 15/16] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2021-07-30 11:24 ` [PATCH v11 16/16] Documentation: arm64: describe asymmetric 32-bit support Will Deacon
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