From: Ben Hutchings <ben@decadent.org.uk>
Date: Mon, 27 Nov 2017 20:49:07 +0000 (+0000)
Subject: s390/mm: Avoid ABI change in 4.9.52
X-Git-Tag: archive/raspbian/4.9.80-2+rpi1~8^2~16
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success/%22http:/www.example.com/cgi/success?a=commitdiff_plain;h=47a80efff06c2a92aa826bac110a8b3304e0690b;p=linux-4.9.git

s390/mm: Avoid ABI change in 4.9.52

Commit 60f07c8ec5fa "s390/mm: fix race on mm->context.flush_mm" added
a field to the s390 definition of mm_context_t.  This is embedded in
the arch-indepdendent struct mm_struct, so adding a new field results
in an incompatible change to the layout of the larger struct.

Move the new field out of mm_context_t to the end of mm_struct, and
hide the change from genksyms.


Gbp-Pq: Topic debian
Gbp-Pq: Name s390-mm-avoid-abi-change-in-4.9.52.patch
---

diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h
index af85d6b12028..8dac31f56df9 100644
--- a/arch/s390/include/asm/mmu.h
+++ b/arch/s390/include/asm/mmu.h
@@ -5,7 +5,6 @@
 #include <linux/errno.h>
 
 typedef struct {
-	spinlock_t lock;
 	cpumask_t cpu_attach_mask;
 	atomic_t flush_count;
 	unsigned int flush_mm;
@@ -26,7 +25,7 @@ typedef struct {
 } mm_context_t;
 
 #define INIT_MM_CONTEXT(name)						   \
-	.context.lock =	__SPIN_LOCK_UNLOCKED(name.context.lock),	   \
+	.s390_flush_lock = __SPIN_LOCK_UNLOCKED(name.s390_flush_lock),	   \
 	.context.pgtable_lock =						   \
 			__SPIN_LOCK_UNLOCKED(name.context.pgtable_lock),   \
 	.context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index f65a708ac395..dee12239a36f 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -15,7 +15,7 @@
 static inline int init_new_context(struct task_struct *tsk,
 				   struct mm_struct *mm)
 {
-	spin_lock_init(&mm->context.lock);
+	spin_lock_init(&mm->s390_flush_lock);
 	spin_lock_init(&mm->context.pgtable_lock);
 	INIT_LIST_HEAD(&mm->context.pgtable_list);
 	spin_lock_init(&mm->context.gmap_lock);
diff --git a/arch/s390/include/asm/tlbflush.h b/arch/s390/include/asm/tlbflush.h
index eed927aeb08f..7ddd9824ffd7 100644
--- a/arch/s390/include/asm/tlbflush.h
+++ b/arch/s390/include/asm/tlbflush.h
@@ -96,12 +96,12 @@ static inline void __tlb_flush_kernel(void)
 
 static inline void __tlb_flush_mm_lazy(struct mm_struct * mm)
 {
-	spin_lock(&mm->context.lock);
+	spin_lock(&mm->s390_flush_lock);
 	if (mm->context.flush_mm) {
 		mm->context.flush_mm = 0;
 		__tlb_flush_mm(mm);
 	}
-	spin_unlock(&mm->context.lock);
+	spin_unlock(&mm->s390_flush_lock);
 }
 
 /*
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 6616107518ad..fd22e5f9732f 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -523,6 +523,12 @@ struct mm_struct {
 	atomic_long_t hugetlb_usage;
 #endif
 	struct work_struct async_put_work;
+#ifndef __GENKSYMS__
+#ifdef CONFIG_S390
+	/* bwh: This should be in s390's mm_context_t but that breaks ABI */
+	spinlock_t s390_flush_lock;
+#endif
+#endif
 };
 
 static inline void mm_init_cpumask(struct mm_struct *mm)