Messages in this thread Patch in this message | | | Date | Wed, 24 Feb 2021 13:24:42 +0100 | From | Peter Zijlstra <> | Subject | [PATCH 3/6] sched: Collate affine_move_task() stoppers |
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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()") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/sched/core.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-)
--- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2239,30 +2239,23 @@ static int affine_move_task(struct rq *r 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)) {
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