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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: Chuhong Yuan <hslester96@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Chuhong Yuan 2019-08-08 15:18:26 +08:00 committed by Vasily Gorbik
parent 3434caec5b
commit 40e90656c1
2 changed files with 8 additions and 6 deletions
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4
arch/s390/include/asm/gmap.h
View File

@ -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;

10
arch/s390/mm/gmap.c
View File

@ -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 */