s390/mm: use a single lock for the fields in mm_context_t

The three locks 'lock', 'pgtable_lock' and 'gmap_lock' in the
mm_context_t can be reduced to a single lock.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/mmu.h

@@ -9,9 +9,7 @@ typedef struct {
 	cpumask_t cpu_attach_mask;
 	atomic_t flush_count;
 	unsigned int flush_mm;
-	spinlock_t pgtable_lock;
 	struct list_head pgtable_list;
-	spinlock_t gmap_lock;
 	struct list_head gmap_list;
 	unsigned long gmap_asce;
 	unsigned long asce;
@@ -29,10 +27,7 @@ typedef struct {
 
 #define INIT_MM_CONTEXT(name)						   \
 	.context.lock =	__SPIN_LOCK_UNLOCKED(name.context.lock),	   \
-	.context.pgtable_lock =						   \
-			__SPIN_LOCK_UNLOCKED(name.context.pgtable_lock),   \
 	.context.pgtable_list = LIST_HEAD_INIT(name.context.pgtable_list), \
-	.context.gmap_lock = __SPIN_LOCK_UNLOCKED(name.context.gmap_lock), \
 	.context.gmap_list = LIST_HEAD_INIT(name.context.gmap_list),
 
 static inline int tprot(unsigned long addr)

arch/s390/include/asm/mmu_context.h

@@ -18,9 +18,7 @@ static inline int init_new_context(struct task_struct *tsk,
 				   struct mm_struct *mm)
 {
 	spin_lock_init(&mm->context.lock);
-	spin_lock_init(&mm->context.pgtable_lock);
 	INIT_LIST_HEAD(&mm->context.pgtable_list);
-	spin_lock_init(&mm->context.gmap_lock);
 	INIT_LIST_HEAD(&mm->context.gmap_list);
 	cpumask_clear(&mm->context.cpu_attach_mask);
 	atomic_set(&mm->context.flush_count, 0);

arch/s390/mm/gmap.c

@@ -100,14 +100,14 @@ struct gmap *gmap_create(struct mm_struct *mm, unsigned long limit)
 	if (!gmap)
 		return NULL;
 	gmap->mm = mm;
-	spin_lock(&mm->context.gmap_lock);
+	spin_lock(&mm->context.lock);
 	list_add_rcu(&gmap->list, &mm->context.gmap_list);
 	if (list_is_singular(&mm->context.gmap_list))
 		gmap_asce = gmap->asce;
 	else
 		gmap_asce = -1UL;
 	WRITE_ONCE(mm->context.gmap_asce, gmap_asce);
-	spin_unlock(&mm->context.gmap_lock);
+	spin_unlock(&mm->context.lock);
 	return gmap;
 }
 EXPORT_SYMBOL_GPL(gmap_create);
@@ -248,7 +248,7 @@ void gmap_remove(struct gmap *gmap)
 		spin_unlock(&gmap->shadow_lock);
 	}
 	/* Remove gmap from the pre-mm list */
-	spin_lock(&gmap->mm->context.gmap_lock);
+	spin_lock(&gmap->mm->context.lock);
 	list_del_rcu(&gmap->list);
 	if (list_empty(&gmap->mm->context.gmap_list))
 		gmap_asce = 0;
@@ -258,7 +258,7 @@ void gmap_remove(struct gmap *gmap)
 	else
 		gmap_asce = -1UL;
 	WRITE_ONCE(gmap->mm->context.gmap_asce, gmap_asce);
-	spin_unlock(&gmap->mm->context.gmap_lock);
+	spin_unlock(&gmap->mm->context.lock);
 	synchronize_rcu();
 	/* Put reference */
 	gmap_put(gmap);

arch/s390/mm/pgalloc.c

@@ -188,7 +188,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
 	/* Try to get a fragment of a 4K page as a 2K page table */
 	if (!mm_alloc_pgste(mm)) {
 		table = NULL;
-		spin_lock_bh(&mm->context.pgtable_lock);
+		spin_lock_bh(&mm->context.lock);
 		if (!list_empty(&mm->context.pgtable_list)) {
 			page = list_first_entry(&mm->context.pgtable_list,
 						struct page, lru);
@@ -203,7 +203,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
 				list_del(&page->lru);
 			}
 		}
-		spin_unlock_bh(&mm->context.pgtable_lock);
+		spin_unlock_bh(&mm->context.lock);
 		if (table)
 			return table;
 	}
@@ -227,9 +227,9 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
 		/* Return the first 2K fragment of the page */
 		atomic_set(&page->_mapcount, 1);
 		clear_table(table, _PAGE_INVALID, PAGE_SIZE);
-		spin_lock_bh(&mm->context.pgtable_lock);
+		spin_lock_bh(&mm->context.lock);
 		list_add(&page->lru, &mm->context.pgtable_list);
-		spin_unlock_bh(&mm->context.pgtable_lock);
+		spin_unlock_bh(&mm->context.lock);
 	}
 	return table;
 }
@@ -243,13 +243,13 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
 	if (!mm_alloc_pgste(mm)) {
 		/* Free 2K page table fragment of a 4K page */
 		bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
-		spin_lock_bh(&mm->context.pgtable_lock);
+		spin_lock_bh(&mm->context.lock);
 		mask = atomic_xor_bits(&page->_mapcount, 1U << bit);
 		if (mask & 3)
 			list_add(&page->lru, &mm->context.pgtable_list);
 		else
 			list_del(&page->lru);
-		spin_unlock_bh(&mm->context.pgtable_lock);
+		spin_unlock_bh(&mm->context.lock);
 		if (mask != 0)
 			return;
 	}
@@ -275,13 +275,13 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table,
 		return;
 	}
 	bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
-	spin_lock_bh(&mm->context.pgtable_lock);
+	spin_lock_bh(&mm->context.lock);
 	mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit);
 	if (mask & 3)
 		list_add_tail(&page->lru, &mm->context.pgtable_list);
 	else
 		list_del(&page->lru);
-	spin_unlock_bh(&mm->context.pgtable_lock);
+	spin_unlock_bh(&mm->context.lock);
 	table = (unsigned long *) (__pa(table) | (1U << bit));
 	tlb_remove_table(tlb, table);
 }