From e62b758a0149648256ed0fa194d9e107e294d8aa Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 8 Jun 2021 00:37:32 -0400 Subject: [PATCH 291/323] sched: Collate affine_move_task() stoppers Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz commit 58b1a45086b5f80f2b2842aa7ed0da51a64a302b upstream. The SCA_MIGRATE_ENABLE and task_running() cases are almost identical, collapse them to avoid further duplication. Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()") Cc: stable@kernel.org Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210224131355.500108964@infradead.org Signed-off-by: Paul Gortmaker Signed-off-by: Steven Rostedt (VMware) --- kernel/sched/core.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 31fa925852e5..3130289baf79 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2291,30 +2291,23 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag return -EINVAL; } - if (flags & SCA_MIGRATE_ENABLE) { - - refcount_inc(&pending->refs); /* pending->{arg,stop_work} */ - p->migration_flags &= ~MDF_PUSH; - task_rq_unlock(rq, p, rf); - - stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop, - &pending->arg, &pending->stop_work); - - return 0; - } - if (task_running(rq, p) || p->state == TASK_WAKING) { /* - * Lessen races (and headaches) by delegating - * is_migration_disabled(p) checks to the stopper, which will - * run on the same CPU as said p. + * MIGRATE_ENABLE gets here because 'p == current', but for + * anything else we cannot do is_migration_disabled(), punt + * and have the stopper function handle it all race-free. */ + refcount_inc(&pending->refs); /* pending->{arg,stop_work} */ + if (flags & SCA_MIGRATE_ENABLE) + p->migration_flags &= ~MDF_PUSH; task_rq_unlock(rq, p, rf); stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop, &pending->arg, &pending->stop_work); + if (flags & SCA_MIGRATE_ENABLE) + return 0; } else { if (!is_migration_disabled(p)) { -- 2.43.0