The following commit has been merged into the sched/core branch of tip:
Commit-ID: b965f1ddb47daa5b8b2e2bc9c921431236830367
Gitweb:
https://git.kernel.org/tip/b965f1ddb47daa5b8b2e2bc9c921431236830367
Author: Peter Zijlstra (Intel) <pet...@infradead.org>
AuthorDate: Mon, 18 Jan 2021 15:12:20 +01:00
Committer: Ingo Molnar <mi...@kernel.org>
CommitterDate: Wed, 17 Feb 2021 14:12:42 +01:00
preempt/dynamic: Provide cond_resched() and might_resched() static calls
Provide static calls to control cond_resched() (called in !CONFIG_PREEMPT)
and might_resched() (called in CONFIG_PREEMPT_VOLUNTARY) to that we
can override their behaviour when preempt= is overriden.
Since the default behaviour is full preemption, both their calls are
ignored when preempt= isn't passed.
[fweisbec: branch might_resched() directly to __cond_resched(), only
define static calls when PREEMPT_DYNAMIC]
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-6-frede...@kernel.org
---
include/linux/kernel.h | 23 +++++++++++++++++++----
include/linux/sched.h | 27 ++++++++++++++++++++++++---
kernel/sched/core.c | 16 +++++++++++++---
3 files changed, 56 insertions(+), 10 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index f7902d8..cfd3d34 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -15,7 +15,7 @@
#include <linux/typecheck.h>
#include <linux/printk.h>
#include <linux/build_bug.h>
-
+#include <linux/static_call_types.h>
#include <asm/byteorder.h>
#include <uapi/linux/kernel.h>
@@ -81,11 +81,26 @@ struct pt_regs;
struct user;
#ifdef CONFIG_PREEMPT_VOLUNTARY
-extern int _cond_resched(void);
-# define might_resched() _cond_resched()
+
+extern int __cond_resched(void);
+# define might_resched() __cond_resched()
+
+#elif defined(CONFIG_PREEMPT_DYNAMIC)
+
+extern int __cond_resched(void);
+
+DECLARE_STATIC_CALL(might_resched, __cond_resched);
+
+static __always_inline void might_resched(void)
+{
+ static_call(might_resched)();
+}
+
#else
+
# define might_resched() do { } while (0)
-#endif
+
+#endif /* CONFIG_PREEMPT_* */
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
extern void ___might_sleep(const char *file, int line, int preempt_offset);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e115222..2f35594 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1871,11 +1871,32 @@ static inline int test_tsk_need_resched(struct
task_struct *tsk)
* value indicates whether a reschedule was done in fact.
* cond_resched_lock() will drop the spinlock before scheduling,
*/
-#ifndef CONFIG_PREEMPTION
-extern int _cond_resched(void);
+#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
+extern int __cond_resched(void);
+
+#ifdef CONFIG_PREEMPT_DYNAMIC
+
+DECLARE_STATIC_CALL(cond_resched, __cond_resched);
+
+static __always_inline int _cond_resched(void)
+{
+ return static_call(cond_resched)();
+}
+
#else
+
+static inline int _cond_resched(void)
+{
+ return __cond_resched();
+}
+
+#endif /* CONFIG_PREEMPT_DYNAMIC */
+
+#else
+
static inline int _cond_resched(void) { return 0; }
-#endif
+
+#endif /* !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) */
#define cond_resched() ({ \
___might_sleep(__FILE__, __LINE__, 0); \
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4afbdd2..f7c8fd8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6785,17 +6785,27 @@ SYSCALL_DEFINE0(sched_yield)
return 0;
}
-#ifndef CONFIG_PREEMPTION
-int __sched _cond_resched(void)
+#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
+int __sched __cond_resched(void)
{
if (should_resched(0)) {
preempt_schedule_common();
return 1;
}
+#ifndef CONFIG_PREEMPT_RCU
rcu_all_qs();
+#endif
return 0;
}
-EXPORT_SYMBOL(_cond_resched);
+EXPORT_SYMBOL(__cond_resched);
+#endif
+
+#ifdef CONFIG_PREEMPT_DYNAMIC
+DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched);
+EXPORT_STATIC_CALL(cond_resched);
+
+DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched);
+EXPORT_STATIC_CALL(might_resched);
#endif
/*
