[PATCH v2 4/6] sched: dynamic: Simplify irqentry_exit_cond_resched()

[Mark Rutland <mark.rutland@arm.com>]

PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
In either model, irqentry_exit_cond_resched() is always called and never
disabled.

Remove the unnecessary code for this when PREEMPT_DYNAMIC is selected.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Stultz <jstultz@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
---
 include/linux/irq-entry-common.h | 17 +----------------
 kernel/entry/common.c            | 17 ++---------------
 kernel/sched/core.c              |  7 -------
 3 files changed, 3 insertions(+), 38 deletions(-)

diff --git a/include/linux/irq-entry-common.h b/include/linux/irq-entry-common.h
index 1fabf0f5ea8e7..de7e10de91d04 100644
--- a/include/linux/irq-entry-common.h
+++ b/include/linux/irq-entry-common.h
@@ -346,22 +346,7 @@ typedef struct irqentry_state {
  *
  * Conditional reschedule with additional sanity checks.
  */
-void raw_irqentry_exit_cond_resched(void);
-
-#ifdef CONFIG_PREEMPT_DYNAMIC
-#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
-#define irqentry_exit_cond_resched_dynamic_enabled	raw_irqentry_exit_cond_resched
-#define irqentry_exit_cond_resched_dynamic_disabled	NULL
-DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
-#define irqentry_exit_cond_resched()	static_call(irqentry_exit_cond_resched)()
-#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
-DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
-void dynamic_irqentry_exit_cond_resched(void);
-#define irqentry_exit_cond_resched()	dynamic_irqentry_exit_cond_resched()
-#endif
-#else /* CONFIG_PREEMPT_DYNAMIC */
-#define irqentry_exit_cond_resched()	raw_irqentry_exit_cond_resched()
-#endif /* CONFIG_PREEMPT_DYNAMIC */
+void irqentry_exit_cond_resched(void);
 
 /**
  * irqentry_enter_from_kernel_mode - Establish state before invoking the irq handler
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index e3d381fd3d251..e234b04373fea 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -123,7 +123,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
 /**
  * arch_irqentry_exit_need_resched - Architecture specific need resched function
  *
- * Invoked from raw_irqentry_exit_cond_resched() to check if resched is needed.
+ * Invoked from irqentry_exit_cond_resched() to check if resched is needed.
  * Defaults return true.
  *
  * The main purpose is to permit arch to avoid preemption of a task from an IRQ.
@@ -134,7 +134,7 @@ static inline bool arch_irqentry_exit_need_resched(void);
 static inline bool arch_irqentry_exit_need_resched(void) { return true; }
 #endif
 
-void raw_irqentry_exit_cond_resched(void)
+void irqentry_exit_cond_resched(void)
 {
 	if (!preempt_count()) {
 		/* Sanity check RCU and thread stack */
@@ -145,19 +145,6 @@ void raw_irqentry_exit_cond_resched(void)
 			preempt_schedule_irq();
 	}
 }
-#ifdef CONFIG_PREEMPT_DYNAMIC
-#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
-DEFINE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched);
-#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
-DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
-void dynamic_irqentry_exit_cond_resched(void)
-{
-	if (!static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
-		return;
-	raw_irqentry_exit_cond_resched();
-}
-#endif
-#endif
 
 noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
 {
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f88b9ef70a0dd..4f754f4a472f8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7788,9 +7788,6 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
 # endif
 
 /*
- * SC:irqentry_exit_cond_resched
- *
- *
  * NONE:
  *   (unselectable)
  *
@@ -7798,11 +7795,9 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
  *   (unselectable)
  *
  * FULL:
- *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
  *   dynamic_preempt_lazy       <- false
  *
  * LAZY:
- *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
  *   dynamic_preempt_lazy       <- true
  */
 
@@ -7846,14 +7841,12 @@ static void __sched_dynamic_update(int mode)
 {
 	switch (mode) {
 	case preempt_dynamic_full:
-		preempt_dynamic_enable(irqentry_exit_cond_resched);
 		preempt_dynamic_key_disable(preempt_lazy);
 		if (mode != preempt_dynamic_mode)
 			pr_info("Dynamic Preempt: full\n");
 		break;
 
 	case preempt_dynamic_lazy:
-		preempt_dynamic_enable(irqentry_exit_cond_resched);
 		preempt_dynamic_key_enable(preempt_lazy);
 		if (mode != preempt_dynamic_mode)
 			pr_info("Dynamic Preempt: lazy\n");
-- 
2.30.2