From: Helge Deller <deller@gmx.de>
Date: Mon, 29 May 2017 17:14:16 +0200
Subject: [PATCH] parisc/mm: Ensure IRQs are off in switch_mm()
References: bnc#1060662
Patch-mainline: v4.12.3
Git-commit: 649aa24254e85bf6bd7807dd372d083707852b1f

commit 649aa24254e85bf6bd7807dd372d083707852b1f upstream.

This is because of commit f98db6013c55 ("sched/core: Add switch_mm_irqs_off()
and use it in the scheduler") in which switch_mm_irqs_off() is called by the
scheduler, vs switch_mm() which is used by use_mm().

This patch lets the parisc code mirror the x86 and powerpc code, ie. it
disables interrupts in switch_mm(), and optimises the scheduler case by
defining switch_mm_irqs_off().

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 arch/parisc/include/asm/mmu_context.h | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/parisc/include/asm/mmu_context.h b/arch/parisc/include/asm/mmu_context.h
index 59be25764433..a81226257878 100644
--- a/arch/parisc/include/asm/mmu_context.h
+++ b/arch/parisc/include/asm/mmu_context.h
@@ -49,15 +49,26 @@ static inline void load_context(mm_context_t context)
 	mtctl(__space_to_prot(context), 8);
 }
 
-static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk)
+static inline void switch_mm_irqs_off(struct mm_struct *prev,
+		struct mm_struct *next, struct task_struct *tsk)
 {
-
 	if (prev != next) {
 		mtctl(__pa(next->pgd), 25);
 		load_context(next->context);
 	}
 }
 
+static inline void switch_mm(struct mm_struct *prev,
+		struct mm_struct *next, struct task_struct *tsk)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	switch_mm_irqs_off(prev, next, tsk);
+	local_irq_restore(flags);
+}
+#define switch_mm_irqs_off switch_mm_irqs_off
+
 #define deactivate_mm(tsk,mm)	do { } while (0)
 
 static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
-- 
2.14.2