iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

sched/uclamp: Fix initialization of struct uclamp_rq

Browse Source 
[ 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>
This commit is contained in:
Qais Yousef 2020-06-30 12:21:22 +01:00 committed by Greg Kroah-Hartman
parent 4d7115d292
commit 047187eb0a
1 changed files with 16 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
kernel/sched/core.c
View File

@ -1238,6 +1238,20 @@ 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 = {};
@ -1246,11 +1260,8 @@ 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],