Messages in this thread Patch in this message | | | Date | Thu, 17 Sep 2020 11:42:07 +0200 | From | Thomas Gleixner <> | Subject | [patch 05/10] sched/core: Split __set_cpus_allowed_ptr() |
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Split the function so the actual work part can be reused and called from places which hold rq::lock already.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- kernel/sched/core.c | 64 ++++++++++++++++++++++++++++++---------------------- 1 file changed, 38 insertions(+), 26 deletions(-)
--- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1863,34 +1863,17 @@ void do_set_cpus_allowed(struct task_str set_next_task(rq, p); } -/* - * Change a given task's CPU affinity. Migrate the thread to a - * proper CPU and schedule it away if the CPU it's executing on - * is removed from the allowed bitmask. - * - * NOTE: the caller must have a valid reference to the task, the - * task must not exit() & deallocate itself prematurely. The - * call is not atomic; no spinlocks may be held. - */ -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; - rq = task_rq_lock(p, &rf); update_rq_clock(rq); - if (p->flags & PF_KTHREAD) { - /* - * Kernel threads are allowed on online && !active CPUs - */ - cpu_valid_mask = cpu_online_mask; - } - /* * Must re-check here, to close a race against __kthread_bind(), * sched_setaffinity() is not guaranteed to observe the flag. @@ -1900,8 +1883,12 @@ static int __set_cpus_allowed_ptr(struct goto out; } - if (cpumask_equal(&p->cpus_mask, new_mask)) - goto out; + if (p->flags & PF_KTHREAD) { + /* + * Kernel threads are allowed on online && !active CPUs + */ + cpu_valid_mask = cpu_online_mask; + } /* * Picking a ~random cpu helps in cases where we are changing affinity @@ -1933,7 +1920,7 @@ static int __set_cpus_allowed_ptr(struct 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)) { @@ -1941,10 +1928,35 @@ static int __set_cpus_allowed_ptr(struct * 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); + return ret; +} + +/* + * Change a given task's CPU affinity. Migrate the thread to a + * proper CPU and schedule it away if the CPU it's executing on + * is removed from the allowed bitmask. + * + * NOTE: the caller must have a valid reference to the task, the + * task must not exit() & deallocate itself prematurely. The + * call is not atomic; no spinlocks may be held. + */ +static int __set_cpus_allowed_ptr(struct task_struct *p, + const struct cpumask *new_mask, bool check) +{ + struct rq_flags rf; + struct rq *rq; + int ret = 0; + + rq = task_rq_lock(p, &rf); + + if (cpumask_equal(&p->cpus_mask, new_mask)) + task_rq_unlock(rq, p, &rf); + else + ret = set_cpus_allowed_ptr_locked(p, new_mask, check, rq, &rf); return ret; }
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