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Commit 40e90656 authored by Chuhong Yuan's avatar Chuhong Yuan Committed by Vasily Gorbik
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s390/mm: use refcount_t for refcount 

Reference counters are preferred to use refcount_t instead of
atomic_t.
This is because the implementation of refcount_t can prevent
overflows and detect possible use-after-free.
So convert atomic_t ref counters to refcount_t.

Link: http://lkml.kernel.org/r/20190808071826.6649-1-hslester96@gmail.com


Signed-off-by: default avatarChuhong Yuan <hslester96@gmail.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 3434caec

arch/s390/include/asm/gmap.h

+3 −1
Original line number Diff line number Diff line
@@ -9,6 +9,8 @@ 
#ifndef _ASM_S390_GMAP_H

#define _ASM_S390_GMAP_H



#include <linux/refcount.h>



/* Generic bits for GMAP notification on DAT table entry changes. */

#define GMAP_NOTIFY_SHADOW	0x2

#define GMAP_NOTIFY_MPROT	0x1
@@ -46,7 +48,7 @@ struct gmap { 
	struct radix_tree_root guest_to_host;

	struct radix_tree_root host_to_guest;

	spinlock_t guest_table_lock;

	atomic_t ref_count;

	refcount_t ref_count;

	unsigned long *table;

	unsigned long asce;

	unsigned long asce_end;

arch/s390/mm/gmap.c

+5 −5
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ static struct gmap *gmap_alloc(unsigned long limit) 
	INIT_RADIX_TREE(&gmap->host_to_rmap, GFP_ATOMIC);

	spin_lock_init(&gmap->guest_table_lock);

	spin_lock_init(&gmap->shadow_lock);

	atomic_set(&gmap->ref_count, 1);

	refcount_set(&gmap->ref_count, 1);

	page = alloc_pages(GFP_KERNEL, CRST_ALLOC_ORDER);

	if (!page)

		goto out_free;
@@ -214,7 +214,7 @@ static void gmap_free(struct gmap *gmap) 
 */

struct gmap *gmap_get(struct gmap *gmap)

{

	atomic_inc(&gmap->ref_count);

	refcount_inc(&gmap->ref_count);

	return gmap;

}

EXPORT_SYMBOL_GPL(gmap_get);
@@ -227,7 +227,7 @@ EXPORT_SYMBOL_GPL(gmap_get); 
 */

void gmap_put(struct gmap *gmap)

{

	if (atomic_dec_return(&gmap->ref_count) == 0)

	if (refcount_dec_and_test(&gmap->ref_count))

		gmap_free(gmap);

}

EXPORT_SYMBOL_GPL(gmap_put);
@@ -1594,7 +1594,7 @@ static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce, 
			continue;

		if (!sg->initialized)

			return ERR_PTR(-EAGAIN);

		atomic_inc(&sg->ref_count);

		refcount_inc(&sg->ref_count);

		return sg;

	}

	return NULL;
@@ -1682,7 +1682,7 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce, 
			}

		}

	}

	atomic_set(&new->ref_count, 2);

	refcount_set(&new->ref_count, 2);

	list_add(&new->list, &parent->children);

	if (asce & _ASCE_REAL_SPACE) {

		/* nothing to protect, return right away */