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From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 23 Oct 2020 12:12:06 +0200
Subject: [PATCH 08/19] sched: Massage set_cpus_allowed()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.21-rt34.tar.xz
Thread a u32 flags word through the *set_cpus_allowed*() callchain.
This will allow adding behavioural tweaks for future users.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/sched/core.c | 28 ++++++++++++++++++----------
kernel/sched/deadline.c | 5 +++--
kernel/sched/sched.h | 7 +++++--
3 files changed, 26 insertions(+), 14 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1822,13 +1822,14 @@ static int migration_cpu_stop(void *data
* sched_class::set_cpus_allowed must do the below, but is not required to
* actually call this function.
*/
-void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
+void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask, u32 flags)
{
cpumask_copy(&p->cpus_mask, new_mask);
p->nr_cpus_allowed = cpumask_weight(new_mask);
}
-void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+static void
+__do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask, u32 flags)
{
struct rq *rq = task_rq(p);
bool queued, running;
@@ -1849,7 +1850,7 @@ void do_set_cpus_allowed(struct task_str
if (running)
put_prev_task(rq, p);
- p->sched_class->set_cpus_allowed(p, new_mask);
+ p->sched_class->set_cpus_allowed(p, new_mask, flags);
if (queued)
enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
@@ -1857,6 +1858,11 @@ void do_set_cpus_allowed(struct task_str
set_next_task(rq, p);
}
+void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+{
+ __do_set_cpus_allowed(p, new_mask, 0);
+}
+
/*
* Change a given task's CPU affinity. Migrate the thread to a
* proper CPU and schedule it away if the CPU it's executing on
@@ -1867,7 +1873,8 @@ void do_set_cpus_allowed(struct task_str
* call is not atomic; no spinlocks may be held.
*/
static int __set_cpus_allowed_ptr(struct task_struct *p,
- const struct cpumask *new_mask, bool check)
+ const struct cpumask *new_mask,
+ u32 flags)
{
const struct cpumask *cpu_valid_mask = cpu_active_mask;
unsigned int dest_cpu;
@@ -1889,7 +1896,7 @@ static int __set_cpus_allowed_ptr(struct
* Must re-check here, to close a race against __kthread_bind(),
* sched_setaffinity() is not guaranteed to observe the flag.
*/
- if (check && (p->flags & PF_NO_SETAFFINITY)) {
+ if ((flags & SCA_CHECK) && (p->flags & PF_NO_SETAFFINITY)) {
ret = -EINVAL;
goto out;
}
@@ -1908,7 +1915,7 @@ static int __set_cpus_allowed_ptr(struct
goto out;
}
- do_set_cpus_allowed(p, new_mask);
+ __do_set_cpus_allowed(p, new_mask, flags);
if (p->flags & PF_KTHREAD) {
/*
@@ -1945,7 +1952,7 @@ static int __set_cpus_allowed_ptr(struct
int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
{
- return __set_cpus_allowed_ptr(p, new_mask, false);
+ return __set_cpus_allowed_ptr(p, new_mask, 0);
}
EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
@@ -2404,7 +2411,8 @@ void sched_set_stop_task(int cpu, struct
#else
static inline int __set_cpus_allowed_ptr(struct task_struct *p,
- const struct cpumask *new_mask, bool check)
+ const struct cpumask *new_mask,
+ u32 flags)
{
return set_cpus_allowed_ptr(p, new_mask);
}
@@ -6009,7 +6017,7 @@ long sched_setaffinity(pid_t pid, const
}
#endif
again:
- retval = __set_cpus_allowed_ptr(p, new_mask, true);
+ retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK);
if (!retval) {
cpuset_cpus_allowed(p, cpus_allowed);
@@ -6588,7 +6596,7 @@ void init_idle(struct task_struct *idle,
*
* And since this is boot we can forgo the serialization.
*/
- set_cpus_allowed_common(idle, cpumask_of(cpu));
+ set_cpus_allowed_common(idle, cpumask_of(cpu), 0);
#endif
/*
* We're having a chicken and egg problem, even though we are
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2307,7 +2307,8 @@ static void task_woken_dl(struct rq *rq,
}
static void set_cpus_allowed_dl(struct task_struct *p,
- const struct cpumask *new_mask)
+ const struct cpumask *new_mask,
+ u32 flags)
{
struct root_domain *src_rd;
struct rq *rq;
@@ -2336,7 +2337,7 @@ static void set_cpus_allowed_dl(struct t
raw_spin_unlock(&src_dl_b->lock);
}
- set_cpus_allowed_common(p, new_mask);
+ set_cpus_allowed_common(p, new_mask, flags);
}
/* Assumes rq->lock is held */
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1809,7 +1809,8 @@ struct sched_class {
void (*task_woken)(struct rq *this_rq, struct task_struct *task);
void (*set_cpus_allowed)(struct task_struct *p,
- const struct cpumask *newmask);
+ const struct cpumask *newmask,
+ u32 flags);
void (*rq_online)(struct rq *rq);
void (*rq_offline)(struct rq *rq);
@@ -1902,7 +1903,9 @@ extern void update_group_capacity(struct
extern void trigger_load_balance(struct rq *rq);
-extern void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask);
+#define SCA_CHECK 0x01
+
+extern void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask, u32 flags);
#endif
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