| Date | Wed, 5 Sep 2018 12:45:45 +0200 | From | Juri Lelli <> | Subject | Re: [PATCH v4 02/16] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups |
| |
Hi,
On 28/08/18 14:53, Patrick Bellasi wrote:
[...]
> static inline int __setscheduler_uclamp(struct task_struct *p, > const struct sched_attr *attr) > { > - if (attr->sched_util_min > attr->sched_util_max) > - return -EINVAL; > - if (attr->sched_util_max > SCHED_CAPACITY_SCALE) > - return -EINVAL; > + int group_id[UCLAMP_CNT] = { UCLAMP_NOT_VALID }; > + int lower_bound, upper_bound; > + struct uclamp_se *uc_se; > + int result = 0; > > - p->uclamp[UCLAMP_MIN] = attr->sched_util_min; > - p->uclamp[UCLAMP_MAX] = attr->sched_util_max; > + mutex_lock(&uclamp_mutex);
This is going to get called from an rcu_read_lock() section, which is a no-go for using mutexes:
sys_sched_setattr -> rcu_read_lock() ... sched_setattr() -> __sched_setscheduler() -> ... __setscheduler_uclamp() -> ... mutex_lock()
Guess you could fix the issue by getting the task struct after find_ process_by_pid() in sys_sched_attr() and then calling sched_setattr() after rcu_read_lock() (putting the task struct at the end). Peter actually suggested this mod to solve a different issue.
Best,
- Juri
|