[PATCH -next v5 10/22] entry: Add arch_irqentry_exit_need_resched() for arm64

[Jinjie Ruan <ruanjinjie@xxxxxxxxxx>]

ARM64 requires an additional check whether to reschedule on return
from interrupt.

Add arch_irqentry_exit_need_resched() as the default NOP
implementation and hook it up into the need_resched() condition in
raw_irqentry_exit_cond_resched().

This allows ARM64 to implement the architecture specific version for
switching over to the generic entry code.

Suggested-by: Mark Rutland <mark.rutland@xxxxxxx>
Suggested-by: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
 kernel/entry/common.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index b82032777310..4aa9656fa1b4 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -142,6 +142,20 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs 
*regs)
        return ret;
 }
 
+/**
+ * arch_irqentry_exit_need_resched - Architecture specific need resched 
function
+ *
+ * Invoked from raw_irqentry_exit_cond_resched() to check if need resched.
+ * Defaults return true.
+ *
+ * The main purpose is to permit arch to skip preempt a task from an IRQ.
+ */
+static inline bool arch_irqentry_exit_need_resched(void);
+
+#ifndef arch_irqentry_exit_need_resched
+static inline bool arch_irqentry_exit_need_resched(void) { return true; }
+#endif
+
 void raw_irqentry_exit_cond_resched(void)
 {
        if (!preempt_count()) {
@@ -149,7 +163,7 @@ void raw_irqentry_exit_cond_resched(void)
                rcu_irq_exit_check_preempt();
                if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
                        WARN_ON_ONCE(!on_thread_stack());
-               if (need_resched())
+               if (need_resched() && arch_irqentry_exit_need_resched())
                        preempt_schedule_irq();
        }
 }
-- 
2.34.1