LinuxLists.cc - [PATCH 1/3] sched/uclamp: Fix a uninitialized variable warnings

2022-11-27 14:29:44

Subject: [PATCH 1/3] sched/uclamp: Fix a uninitialized variable warnings

2022-12-01 22:42:01

Subject: Re: [PATCH 1/3] sched/uclamp: Fix a uninitialized variable warnings

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 <[email protected]>
> Reported-by: Dan Carpenter <[email protected]>
> Signed-off-by: Qais Yousef (Google) <[email protected]>
> ---
> 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;

2022-12-03 14:34:31

by Qais Yousef

[permalink] [raw]

Subject: Re: [PATCH 1/3] sched/uclamp: Fix a uninitialized variable warnings

On 12/01/22 23:38, Dietmar Eggemann wrote:
> 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 <[email protected]>
> > Reported-by: Dan Carpenter <[email protected]>
> > Signed-off-by: Qais Yousef (Google) <[email protected]>
> > ---
> > 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?

Yep, that's better!

Thanks!

--
Qais Yousef

>
> 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;

2022-12-08 15:06:46

by Qais Yousef

[permalink] [raw]

Subject: [PATCH v2] sched/uclamp: Fix a uninitialized variable warnings

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 <[email protected]>
Reported-by: Dan Carpenter <[email protected]>
Signed-off-by: Qais Yousef (Google) <[email protected]>
---

Changes in v2:

* Improve indentation as suggested by Dietmar

kernel/sched/fair.c | 35 ++++++++++++++++-------------------
1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4cc56c91e06e..6a2fc2ca5078 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;
@@ -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)))
@@ -7257,24 +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))) {
- util_min = p_util_min;
- util_max = p_util_max;
- } else {
- /*
- * 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;
--
2.25.1