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Subject[PATCH 6/9] sched: Massage set_cpus_allowed
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>
---
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
@@ -1828,13 +1828,14 @@ 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;
@@ -1855,7 +1856,7 @@ 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);
@@ -1863,6 +1864,11 @@ 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
@@ -1873,7 +1879,8 @@ 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;
@@ -1895,7 +1902,7 @@ 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;
}
@@ -1914,7 +1921,7 @@ 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) {
/*
@@ -1951,7 +1958,7 @@ 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);

@@ -2410,7 +2417,8 @@ 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);
}
@@ -6025,7 +6033,7 @@ 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);
@@ -6608,7 +6616,7 @@ 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
@@ -2280,7 +2280,8 @@ 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;
@@ -2309,7 +2310,7 @@ 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
@@ -1806,7 +1806,8 @@ 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);
@@ -1899,7 +1900,9 @@ 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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