| From 1ae59c1905cb6da41f64ecb615acce4710ff1422 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 30 Jun 2020 12:21:22 +0100 |
| Subject: sched/uclamp: Fix initialization of struct uclamp_rq |
| |
| From: Qais Yousef <qais.yousef@arm.com> |
| |
| [ Upstream commit d81ae8aac85ca2e307d273f6dc7863a721bf054e ] |
| |
| struct uclamp_rq was zeroed out entirely in assumption that in the first |
| call to uclamp_rq_inc() they'd be initialized correctly in accordance to |
| default settings. |
| |
| But when next patch introduces a static key to skip |
| uclamp_rq_{inc,dec}() until userspace opts in to use uclamp, schedutil |
| will fail to perform any frequency changes because the |
| rq->uclamp[UCLAMP_MAX].value is zeroed at init and stays as such. Which |
| means all rqs are capped to 0 by default. |
| |
| Fix it by making sure we do proper initialization at init without |
| relying on uclamp_rq_inc() doing it later. |
| |
| Fixes: 69842cba9ace ("sched/uclamp: Add CPU's clamp buckets refcounting") |
| Signed-off-by: Qais Yousef <qais.yousef@arm.com> |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> |
| Tested-by: Lukasz Luba <lukasz.luba@arm.com> |
| Link: https://lkml.kernel.org/r/20200630112123.12076-2-qais.yousef@arm.com |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| kernel/sched/core.c | 21 ++++++++++++++++----- |
| 1 file changed, 16 insertions(+), 5 deletions(-) |
| |
| diff --git a/kernel/sched/core.c b/kernel/sched/core.c |
| index a7ef76a62699a..1bae86fc128b2 100644 |
| --- a/kernel/sched/core.c |
| +++ b/kernel/sched/core.c |
| @@ -1237,6 +1237,20 @@ static void uclamp_fork(struct task_struct *p) |
| } |
| } |
| |
| +static void __init init_uclamp_rq(struct rq *rq) |
| +{ |
| + enum uclamp_id clamp_id; |
| + struct uclamp_rq *uc_rq = rq->uclamp; |
| + |
| + for_each_clamp_id(clamp_id) { |
| + uc_rq[clamp_id] = (struct uclamp_rq) { |
| + .value = uclamp_none(clamp_id) |
| + }; |
| + } |
| + |
| + rq->uclamp_flags = 0; |
| +} |
| + |
| static void __init init_uclamp(void) |
| { |
| struct uclamp_se uc_max = {}; |
| @@ -1245,11 +1259,8 @@ static void __init init_uclamp(void) |
| |
| mutex_init(&uclamp_mutex); |
| |
| - for_each_possible_cpu(cpu) { |
| - memset(&cpu_rq(cpu)->uclamp, 0, |
| - sizeof(struct uclamp_rq)*UCLAMP_CNT); |
| - cpu_rq(cpu)->uclamp_flags = 0; |
| - } |
| + for_each_possible_cpu(cpu) |
| + init_uclamp_rq(cpu_rq(cpu)); |
| |
| for_each_clamp_id(clamp_id) { |
| uclamp_se_set(&init_task.uclamp_req[clamp_id], |
| -- |
| 2.25.1 |
| |