[RFC][PATCH 4/5] static_call: Remove DEFINE_STATIC_CALL_RET0() and its uses

[Josh Poimboeuf <jpoimboe@kernel.org>]

DEFINE_STATIC_CALL_RET0() is now identical to DEFINE_STATIC_CALL_NULL().
All static calls to NULL function pointers are actually calls to "do
nothing return 0" functions.

Replace all DEFINE_STATIC_CALL_RET0() usages and remove it.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 arch/powerpc/kernel/irq.c   |  2 +-
 arch/x86/events/amd/core.c  |  2 +-
 arch/x86/events/core.c      |  2 +-
 include/linux/static_call.h |  7 -------
 kernel/events/core.c        |  8 ++++----
 kernel/sched/core.c         | 10 +++++-----
 6 files changed, 12 insertions(+), 19 deletions(-)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index c9535f2760b5..320e1a41abd6 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -220,7 +220,7 @@ static __always_inline void call_do_softirq(const void *sp)
 }
 #endif
 
-DEFINE_STATIC_CALL_RET0(ppc_get_irq, *ppc_md.get_irq);
+DEFINE_STATIC_CALL_NULL(ppc_get_irq, *ppc_md.get_irq);
 
 static void __do_irq(struct pt_regs *regs, unsigned long oldsp)
 {
diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 8c45b198b62f..3c545595bfeb 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -330,7 +330,7 @@ static inline bool amd_is_pair_event_code(struct hw_perf_event *hwc)
 	}
 }
 
-DEFINE_STATIC_CALL_RET0(amd_pmu_branch_hw_config, *x86_pmu.hw_config);
+DEFINE_STATIC_CALL_NULL(amd_pmu_branch_hw_config, *x86_pmu.hw_config);
 
 static int amd_core_hw_config(struct perf_event *event)
 {
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index c94537501091..3f662c16aa08 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -96,7 +96,7 @@ DEFINE_STATIC_CALL_NULL(x86_pmu_filter, *x86_pmu.filter);
  * This one is magic, it will get called even when PMU init fails (because
  * there is no PMU), in which case it should simply return NULL.
  */
-DEFINE_STATIC_CALL_RET0(x86_pmu_guest_get_msrs, *x86_pmu.guest_get_msrs);
+DEFINE_STATIC_CALL_NULL(x86_pmu_guest_get_msrs, *x86_pmu.guest_get_msrs);
 
 u64 __read_mostly hw_cache_event_ids
 				[PERF_COUNT_HW_CACHE_MAX]
diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index 3b3e9e9a1582..6b8d7b687c13 100644
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -17,7 +17,6 @@
  *   DECLARE_STATIC_CALL(name, func);
  *   DEFINE_STATIC_CALL(name, func);
  *   DEFINE_STATIC_CALL_NULL(name, typename);
- *   DEFINE_STATIC_CALL_RET0(name, typename);
  *
  *   __static_call_return0;
  *
@@ -171,8 +170,6 @@ extern int static_call_text_reserved(void *start, void *end);
 	};								\
 	ARCH_DEFINE_STATIC_CALL_RET0_TRAMP(name)
 
-#define DEFINE_STATIC_CALL_RET0 DEFINE_STATIC_CALL_NULL
-
 #define EXPORT_STATIC_CALL(name)					\
 	EXPORT_SYMBOL(STATIC_CALL_KEY(name));				\
 	EXPORT_SYMBOL(STATIC_CALL_TRAMP(name))
@@ -206,8 +203,6 @@ static inline int static_call_init(void) { return 0; }
 	};								\
 	ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name)
 
-#define DEFINE_STATIC_CALL_RET0 DEFINE_STATIC_CALL_NULL
-
 static inline
 void __static_call_update(struct static_call_key *key, void *tramp, void *func)
 {
@@ -251,8 +246,6 @@ static inline int static_call_init(void) { return 0; }
 #define DEFINE_STATIC_CALL_NULL(name, _func)				\
 	__DEFINE_STATIC_CALL(name, _func, __static_call_return0)
 
-#define DEFINE_STATIC_CALL_RET0 DEFINE_STATIC_CALL_NULL
-
 static inline
 void __static_call_update(struct static_call_key *key, void *tramp, void *func)
 {
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f79fd8b87f75..42017f696e2e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6757,9 +6757,9 @@ static void perf_pending_task(struct callback_head *head)
 #ifdef CONFIG_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
-DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
-DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
-DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
+DEFINE_STATIC_CALL_NULL(__perf_guest_state, *perf_guest_cbs->state);
+DEFINE_STATIC_CALL_NULL(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
+DEFINE_STATIC_CALL_NULL(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
 
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
@@ -13766,4 +13766,4 @@ struct cgroup_subsys perf_event_cgrp_subsys = {
 };
 #endif /* CONFIG_CGROUP_PERF */
 
-DEFINE_STATIC_CALL_RET0(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t);
+DEFINE_STATIC_CALL_NULL(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index af017e038b48..cf50562277b7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8492,12 +8492,12 @@ EXPORT_SYMBOL(__cond_resched);
 #if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
 #define cond_resched_dynamic_enabled	__cond_resched
 #define cond_resched_dynamic_disabled	((void *)&__static_call_return0)
-DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched);
+DEFINE_STATIC_CALL_NULL(cond_resched, __cond_resched);
 EXPORT_STATIC_CALL_TRAMP(cond_resched);
 
 #define might_resched_dynamic_enabled	__cond_resched
 #define might_resched_dynamic_disabled	((void *)&__static_call_return0)
-DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched);
+DEFINE_STATIC_CALL_NULL(might_resched, __cond_resched);
 EXPORT_STATIC_CALL_TRAMP(might_resched);
 #elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
 static DEFINE_STATIC_KEY_FALSE(sk_dynamic_cond_resched);
@@ -8598,7 +8598,7 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
  *
  * NONE:
  *   cond_resched               <- __cond_resched
- *   might_resched              <- RET0
+ *   might_resched              <- NULL
  *   preempt_schedule           <- NOP
  *   preempt_schedule_notrace   <- NOP
  *   irqentry_exit_cond_resched <- NOP
@@ -8611,8 +8611,8 @@ EXPORT_SYMBOL(__cond_resched_rwlock_write);
  *   irqentry_exit_cond_resched <- NOP
  *
  * FULL:
- *   cond_resched               <- RET0
- *   might_resched              <- RET0
+ *   cond_resched               <- NULL
+ *   might_resched              <- NULL
  *   preempt_schedule           <- preempt_schedule
  *   preempt_schedule_notrace   <- preempt_schedule_notrace
  *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
-- 
2.39.2