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Message-ID: <20221112174705.pymjyzr4nqhkqfoc@airbuntu>
Date: Sat, 12 Nov 2022 17:47:05 +0000
From: Qais Yousef <qyousef@...alina.io>
To: Dan Carpenter <error27@...il.com>
Cc: oe-kbuild@...ts.linux.dev, Qais Yousef <qais.yousef@....com>,
lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
linux-kernel@...r.kernel.org, x86@...nel.org,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [tip:sched/core 3/19] kernel/sched/fair.c:7263
find_energy_efficient_cpu() error: uninitialized symbol 'util_min'.
On 11/12/22 13:16, Dan Carpenter wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core
> head: 52b33d87b9197c51e8ffdc61873739d90dd0a16f
> commit: 244226035a1f9b2b6c326e55ae5188fab4f428cb [3/19] sched/uclamp: Fix fits_capacity() check in feec()
> config: riscv-randconfig-m031-20221111
> compiler: riscv64-linux-gcc (GCC) 12.1.0
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@...el.com>
> | Reported-by: Dan Carpenter <error27@...il.com>
>
> smatch warnings:
> kernel/sched/fair.c:7263 find_energy_efficient_cpu() error: uninitialized symbol 'util_min'.
> kernel/sched/fair.c:7263 find_energy_efficient_cpu() error: uninitialized symbol 'util_max'.
>
> vim +/util_min +7263 kernel/sched/fair.c
[...]
> util_min/max not initialized if uclamp_is_used() is false. (I thought
> I had reported this earlier but I don't see it on vger).
Thanks Dan!
It's harmless since util_min/max are ignored in util_fits_cpu() too;
uclamp_is_used() is checked there as well.
I couldn't reproduce, I need to get GCC 12.1.0, but the below ought to cure it.
Let me test it a bit more and send a patch.
Thanks
--
Qais Yousef
--->8---
idiff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4cc56c91e06e..89dadaafc1ec 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7217,10 +7217,10 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
eenv_task_busy_time(&eenv, p, prev_cpu);
for (; pd; pd = pd->next) {
+ unsigned long util_min = p_util_min, util_max = p_util_max;
unsigned long cpu_cap, cpu_thermal_cap, util;
unsigned long cur_delta, max_spare_cap = 0;
unsigned long rq_util_min, rq_util_max;
- unsigned long util_min, util_max;
unsigned long prev_spare_cap = 0;
int max_spare_cap_cpu = -1;
unsigned long base_energy;
@@ -7258,10 +7258,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
* aligned with sched_cpu_util().
*/
if (uclamp_is_used()) {
- if (uclamp_rq_is_idle(cpu_rq(cpu))) {
- util_min = p_util_min;
- util_max = p_util_max;
- } else {
+ if (!uclamp_rq_is_idle(cpu_rq(cpu))) {
/*
* Open code uclamp_rq_util_with() except for
* the clamp() part. Ie: apply max aggregation
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