[tip: sched/core] sched/core: Always inline __this_cpu_preempt_check()

[tip-bot2 for Peter Zijlstra]

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

Commit-ID:     f176d4ccb30747231831f66779697afa6d738b3c
Gitweb:        https://git.kernel.org/tip/f176d4ccb30747231831f66779697afa6d738b3c
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Thu, 12 Jan 2023 20:43:59 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 13 Jan 2023 11:48:17 +01:00

sched/core: Always inline __this_cpu_preempt_check()

Quite a few unnecessary instrumentation calls are generated via the
no-op __this_cpu_preempt_check() call, if it gets uninlined by the
compiler:

  vmlinux.o: warning: objtool: in_entry_stack+0x9: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: default_do_nmi+0x10: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: fpu_idle_fpregs+0x41: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: kvm_read_and_reset_apf_flags+0x1: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: lockdep_hardirqs_on+0xb0: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: lockdep_hardirqs_off+0xae: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: irqentry_nmi_enter+0x69: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: irqentry_nmi_exit+0x32: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: acpi_processor_ffh_cstate_enter+0x9: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: acpi_idle_enter+0x43: call to __this_cpu_preempt_check() leaves .noinstr.text section
  vmlinux.o: warning: objtool: acpi_idle_enter_s2idle+0x45: call to __this_cpu_preempt_check() leaves .noinstr.text section

Mark it __always_inline.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: Tony Lindgren <tony@xxxxxxxxxxx>
Tested-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Acked-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230112195542.089981974@xxxxxxxxxxxxx
---
 include/linux/percpu-defs.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index af10715..e60727b 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -310,7 +310,7 @@ extern void __bad_size_call_parameter(void);
 #ifdef CONFIG_DEBUG_PREEMPT
 extern void __this_cpu_preempt_check(const char *op);
 #else
-static inline void __this_cpu_preempt_check(const char *op) { }
+static __always_inline void __this_cpu_preempt_check(const char *op) { }
 #endif
 
 #define __pcpu_size_call_return(stem, variable)				\