[PATCH 13/14] x86/entry: Remove unneeded need_resched() loop

From: Valentin Schneider
Date: Mon Mar 11 2019 - 18:48:30 EST


Since the enabling and disabling of IRQs within preempt_schedule_irq()
is contained in a need_resched() loop, we don't need the outer arch
code loop.

Signed-off-by: Valentin Schneider <valentin.schneider@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
---
arch/x86/entry/entry_32.S | 3 +--
arch/x86/entry/entry_64.S | 3 +--
2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index d309f30cf7af..b1856fe9decf 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -766,13 +766,12 @@ END(ret_from_exception)
#ifdef CONFIG_PREEMPT
ENTRY(resume_kernel)
DISABLE_INTERRUPTS(CLBR_ANY)
-.Lneed_resched:
cmpl $0, PER_CPU_VAR(__preempt_count)
jnz restore_all_kernel
testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off (exception path) ?
jz restore_all_kernel
call preempt_schedule_irq
- jmp .Lneed_resched
+ jmp restore_all_kernel
END(resume_kernel)
#endif

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1f0efdb7b629..e7e270603fe7 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -645,10 +645,9 @@ retint_kernel:
/* Check if we need preemption */
btl $9, EFLAGS(%rsp) /* were interrupts off? */
jnc 1f
-0: cmpl $0, PER_CPU_VAR(__preempt_count)
+ cmpl $0, PER_CPU_VAR(__preempt_count)
jnz 1f
call preempt_schedule_irq
- jmp 0b
1:
#endif
/*
--
2.20.1