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SubjectRe: [PATCH 1/3] sched/uclamp: Fix a uninitialized variable warnings
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On 27/11/2022 15:17, Qais Yousef wrote:
> Addresses the following warnings:
>
>> config: riscv-randconfig-m031-20221111
>> compiler: riscv64-linux-gcc (GCC) 12.1.0
>>
>> 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'.
>
> Fixes: 244226035a1f ("sched/uclamp: Fix fits_capacity() check in feec()")
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <error27@gmail.com>
> Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
> ---
> kernel/sched/fair.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --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

Can we use `struct rq *rq = cpu_rq(cpu)` to reduce nesting and comply
with 80 columns line length?

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 89dadaafc1ec..6a2fc2ca5078 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7239,6 +7239,8 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
eenv.pd_cap = 0;

for_each_cpu(cpu, cpus) {
+ struct rq *rq = cpu_rq(cpu);
+
eenv.pd_cap += cpu_thermal_cap;

if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
@@ -7257,21 +7259,19 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
* much capacity we can get out of the CPU; this is
* aligned with sched_cpu_util().
*/
- if (uclamp_is_used()) {
- if (!uclamp_rq_is_idle(cpu_rq(cpu))) {
- /*
- * Open code uclamp_rq_util_with() except for
- * the clamp() part. Ie: apply max aggregation
- * only. util_fits_cpu() logic requires to
- * operate on non clamped util but must use the
- * max-aggregated uclamp_{min, max}.
- */
- rq_util_min = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN);
- rq_util_max = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX);
-
- util_min = max(rq_util_min, p_util_min);
- util_max = max(rq_util_max, p_util_max);
- }
+ if (uclamp_is_used() && !uclamp_rq_is_idle(rq)) {
+ /*
+ * Open code uclamp_rq_util_with() except for
+ * the clamp() part. Ie: apply max aggregation
+ * only. util_fits_cpu() logic requires to
+ * operate on non clamped util but must use the
+ * max-aggregated uclamp_{min, max}.
+ */
+ rq_util_min = uclamp_rq_get(rq, UCLAMP_MIN);
+ rq_util_max = uclamp_rq_get(rq, UCLAMP_MAX);
+
+ util_min = max(rq_util_min, p_util_min);
+ util_max = max(rq_util_max, p_util_max);
}
if (!util_fits_cpu(util, util_min, util_max, cpu))
continue;
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