From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 23 Mar 2021 15:49:03 +0000 (+0100)
Subject: static_call: Relax static_call_update() function argument type
X-Git-Tag: v5.13-rc1~121^2~3
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9432bbd969c667fc9c4b1c140c5a745ff2a7b540;p=thirdparty%2Fkernel%2Flinux.git

static_call: Relax static_call_update() function argument type

static_call_update() had stronger type requirements than regular C,
relax them to match. Instead of requiring the @func argument has the
exact matching type, allow any type which C is willing to promote to the
right (function) pointer type. Specifically this allows (void *)
arguments.

This cleans up a bunch of static_call_update() callers for
PREEMPT_DYNAMIC and should get around silly GCC11 warnings for free.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YFoN7nCl8OfGtpeh@hirez.programming.kicks-ass.net
---

diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index 85ecc789f4ffd..8d50f62420ca6 100644
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -113,9 +113,9 @@ extern void arch_static_call_transform(void *site, void *tramp, void *func, bool
 
 #define static_call_update(name, func)					\
 ({									\
-	BUILD_BUG_ON(!__same_type(*(func), STATIC_CALL_TRAMP(name)));	\
+	typeof(&STATIC_CALL_TRAMP(name)) __F = (func);			\
 	__static_call_update(&STATIC_CALL_KEY(name),			\
-			     STATIC_CALL_TRAMP_ADDR(name), func);	\
+			     STATIC_CALL_TRAMP_ADDR(name), __F);	\
 })
 
 #ifdef CONFIG_HAVE_STATIC_CALL_INLINE
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 98191218d891d..67f989001894d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5396,25 +5396,25 @@ static void sched_dynamic_update(int mode)
 	switch (mode) {
 	case preempt_dynamic_none:
 		static_call_update(cond_resched, __cond_resched);
-		static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
-		static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
-		static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
-		static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
+		static_call_update(might_resched, (void *)&__static_call_return0);
+		static_call_update(preempt_schedule, NULL);
+		static_call_update(preempt_schedule_notrace, NULL);
+		static_call_update(irqentry_exit_cond_resched, NULL);
 		pr_info("Dynamic Preempt: none\n");
 		break;
 
 	case preempt_dynamic_voluntary:
 		static_call_update(cond_resched, __cond_resched);
 		static_call_update(might_resched, __cond_resched);
-		static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
-		static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
-		static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
+		static_call_update(preempt_schedule, NULL);
+		static_call_update(preempt_schedule_notrace, NULL);
+		static_call_update(irqentry_exit_cond_resched, NULL);
 		pr_info("Dynamic Preempt: voluntary\n");
 		break;
 
 	case preempt_dynamic_full:
-		static_call_update(cond_resched, (typeof(&__cond_resched)) __static_call_return0);
-		static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
+		static_call_update(cond_resched, (void *)&__static_call_return0);
+		static_call_update(might_resched, (void *)&__static_call_return0);
 		static_call_update(preempt_schedule, __preempt_schedule_func);
 		static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
 		static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);