[tip: locking/core] static_call: Relax static_call_update() function argument type

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     9432bbd969c667fc9c4b1c140c5a745ff2a7b540
Gitweb:        https://git.kernel.org/tip/9432bbd969c667fc9c4b1c140c5a745ff2a7b540
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Tue, 23 Mar 2021 16:49:03 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 09 Apr 2021 13:22:12 +02:00

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@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/YFoN7nCl8OfGtpeh@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
---
 include/linux/static_call.h |  4 ++--
 kernel/sched/core.c         | 18 +++++++++---------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index 85ecc78..8d50f62 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 9819121..67f9890 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);