[PATCH 3/4] sched: add a few helpers to wake up tasks on the current cpu

Andrei Vagin
2022-08-30T01:44:27Z

Add complete_on_current_cpu, wake_up_poll_on_current_cpu helpers to wake
up processes on the current CPU.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
---
include/linux/completion.h | 1 +
include/linux/swait.h | 1 +
include/linux/wait.h | 3 +++
kernel/sched/completion.c | 12 ++++++++++++
kernel/sched/core.c | 2 +-
kernel/sched/swait.c | 11 +++++++++++
kernel/sched/wait.c | 5 +++++
7 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/include/linux/completion.h b/include/linux/completion.h
index 51d9ab079629..1699e697a225 100644
--- a/include/linux/completion.h
+++ b/include/linux/completion.h
@@ -115,6 +115,7 @@ extern bool try_wait_for_completion(struct completion *x);
extern bool completion_done(struct completion *x);

extern void complete(struct completion *);
+extern void complete_on_current_cpu(struct completion *x);
extern void complete_all(struct completion *);

#endif
diff --git a/include/linux/swait.h b/include/linux/swait.h
index 6a8c22b8c2a5..1f27b254adf5 100644
--- a/include/linux/swait.h
+++ b/include/linux/swait.h
@@ -147,6 +147,7 @@ static inline bool swq_has_sleeper(struct swait_queue_head *wq)
extern void swake_up_one(struct swait_queue_head *q);
extern void swake_up_all(struct swait_queue_head *q);
extern void swake_up_locked(struct swait_queue_head *q);
+extern void swake_up_locked_on_current_cpu(struct swait_queue_head *q);

extern void prepare_to_swait_exclusive(struct swait_queue_head *q, struct swait_queue *wait, int state);
extern long prepare_to_swait_event(struct swait_queue_head *q, struct swait_queue *wait, int state);
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 58cfbf81447c..dcd01dd4de3e 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -210,6 +210,7 @@ __remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq
}

void __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
+void __wake_up_on_current_cpu(struct wait_queue_head *wq_head, unsigned int mode, void *key);
void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key);
void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head,
unsigned int mode, void *key, wait_queue_entry_t *bookmark);
@@ -237,6 +238,8 @@ void __wake_up_pollfree(struct wait_queue_head *wq_head);
#define key_to_poll(m) ((__force __poll_t)(uintptr_t)(void *)(m))
#define wake_up_poll(x, m) \
__wake_up(x, TASK_NORMAL, 1, poll_to_key(m))
+#define wake_up_poll_on_current_cpu(x, m) \
+ __wake_up_on_current_cpu(x, TASK_NORMAL, poll_to_key(m))
#define wake_up_locked_poll(x, m) \
__wake_up_locked_key((x), TASK_NORMAL, poll_to_key(m))
#define wake_up_interruptible_poll(x, m) \
diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c
index 35f15c26ed54..1ae9b34822ef 100644
--- a/kernel/sched/completion.c
+++ b/kernel/sched/completion.c
@@ -38,6 +38,18 @@ void complete(struct completion *x)
}
EXPORT_SYMBOL(complete);

+void complete_on_current_cpu(struct completion *x)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&x->wait.lock, flags);
+
+ if (x->done != UINT_MAX)
+ x->done++;
+ swake_up_locked_on_current_cpu(&x->wait);
+ raw_spin_unlock_irqrestore(&x->wait.lock, flags);
+}
+
/**
* complete_all: - signals all threads waiting on this completion
* @x: holds the state of this particular completion
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 008be12c31e6..1e164d8fde1a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6813,7 +6813,7 @@ asmlinkage __visible void __sched preempt_schedule_irq(void)
int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
void *key)
{
- WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~WF_SYNC);
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~(WF_SYNC|WF_CURRENT_CPU));
return try_to_wake_up(curr->private, mode, wake_flags);
}
EXPORT_SYMBOL(default_wake_function);
diff --git a/kernel/sched/swait.c b/kernel/sched/swait.c
index 76b9b796e695..9ebe23868942 100644
--- a/kernel/sched/swait.c
+++ b/kernel/sched/swait.c
@@ -31,6 +31,17 @@ void swake_up_locked(struct swait_queue_head *q)
}
EXPORT_SYMBOL(swake_up_locked);

+void swake_up_locked_on_current_cpu(struct swait_queue_head *q)
+{
+ struct swait_queue *curr;
+
+ if (list_empty(&q->task_list))
+ return;
+
+ curr = list_first_entry(&q->task_list, typeof(*curr), task_list);
+ try_to_wake_up(curr->task, TASK_NORMAL, WF_CURRENT_CPU);
+ list_del_init(&curr->task_list);
+}
/*
* Wake up all waiters. This is an interface which is solely exposed for
* completions and not for general usage.
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 9860bb9a847c..9a78bca79419 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -157,6 +157,11 @@ void __wake_up(struct wait_queue_head *wq_head, unsigned int mode,
}
EXPORT_SYMBOL(__wake_up);

+void __wake_up_on_current_cpu(struct wait_queue_head *wq_head, unsigned int mode, void *key)
+{
+ __wake_up_common_lock(wq_head, mode, 1, WF_CURRENT_CPU, key);
+}
+
/*
* Same as __wake_up but called with the spinlock in wait_queue_head_t held.
*/
--
2.37.2