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Thu, 19 Nov 2020 03:03:26 -0800 (PST) Date: Thu, 19 Nov 2020 11:03:23 +0000 From: Quentin Perret To: Will Deacon Subject: Re: [PATCH v3 07/14] sched: Introduce restrict_cpus_allowed_ptr() to limit task CPU affinity Message-ID: <20201119110323.GA2432333@google.com> References: <20201113093720.21106-1-will@kernel.org> <20201113093720.21106-8-will@kernel.org> <20201119091820.GA2416649@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201119091820.GA2416649@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201119_060328_795510_2E8C679C X-CRM114-Status: GOOD ( 19.36 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Marc Zyngier , kernel-team@android.com, Vincent Guittot , Juri Lelli , Ingo Molnar , Peter Zijlstra , Catalin Marinas , Johannes Weiner , linux-kernel@vger.kernel.org, Qais Yousef , Li Zefan , Greg Kroah-Hartman , Tejun Heo , Suren Baghdasaryan , Morten Rasmussen , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thursday 19 Nov 2020 at 09:18:20 (+0000), Quentin Perret wrote: > Hey Will, > > On Friday 13 Nov 2020 at 09:37:12 (+0000), Will Deacon wrote: > > -static int __set_cpus_allowed_ptr(struct task_struct *p, > > - const struct cpumask *new_mask, bool check) > > +static int __set_cpus_allowed_ptr_locked(struct task_struct *p, > > + const struct cpumask *new_mask, > > + bool check, > > + struct rq *rq, > > + struct rq_flags *rf) > > { > > const struct cpumask *cpu_valid_mask = cpu_active_mask; > > unsigned int dest_cpu; > > - struct rq_flags rf; > > - struct rq *rq; > > int ret = 0; > > Should we have a lockdep assertion here? > > > - rq = task_rq_lock(p, &rf); > > update_rq_clock(rq); > > > > if (p->flags & PF_KTHREAD) { > > @@ -1929,7 +1923,7 @@ static int __set_cpus_allowed_ptr(struct task_struct *p, > > if (task_running(rq, p) || p->state == TASK_WAKING) { > > struct migration_arg arg = { p, dest_cpu }; > > /* Need help from migration thread: drop lock and wait. */ > > - task_rq_unlock(rq, p, &rf); > > + task_rq_unlock(rq, p, rf); > > stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); > > return 0; > > } else if (task_on_rq_queued(p)) { > > @@ -1937,20 +1931,69 @@ static int __set_cpus_allowed_ptr(struct task_struct *p, > > * OK, since we're going to drop the lock immediately > > * afterwards anyway. > > */ > > - rq = move_queued_task(rq, &rf, p, dest_cpu); > > + rq = move_queued_task(rq, rf, p, dest_cpu); > > } > > out: > > - task_rq_unlock(rq, p, &rf); > > + task_rq_unlock(rq, p, rf); > > And that's a little odd to have here no? Can we move it back on the > caller's side? Yeah, no, that obviously doesn't work for the stop_one_cpu() call above, so feel free to ignore ... Thanks, Quentin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel