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s390/mm: use refcount_t for refcount

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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
Download Patch File Download Diff File Expand all files Collapse all files

4
arch/s390/include/asm/gmap.h
View File

@@ -9,6 +9,8 @@
#ifndef _ASM_S390_GMAP_H #ifndef _ASM_S390_GMAP_H
#define _ASM_S390_GMAP_H #define _ASM_S390_GMAP_H
#include <linux/refcount.h>
/* Generic bits for GMAP notification on DAT table entry changes. */ /* Generic bits for GMAP notification on DAT table entry changes. */
#define GMAP_NOTIFY_SHADOW 0x2 #define GMAP_NOTIFY_SHADOW 0x2
#define GMAP_NOTIFY_MPROT 0x1 #define GMAP_NOTIFY_MPROT 0x1
@@ -46,7 +48,7 @@ struct gmap {
struct radix_tree_root guest_to_host; struct radix_tree_root guest_to_host;
struct radix_tree_root host_to_guest; struct radix_tree_root host_to_guest;
spinlock_t guest_table_lock; spinlock_t guest_table_lock;
atomic_t ref_count; refcount_t ref_count;
unsigned long *table; unsigned long *table;
unsigned long asce; unsigned long asce;
unsigned long asce_end; 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); INIT_RADIX_TREE(&gmap->host_to_rmap, GFP_ATOMIC);
spin_lock_init(&gmap->guest_table_lock); spin_lock_init(&gmap->guest_table_lock);
spin_lock_init(&gmap->shadow_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); page = alloc_pages(GFP_KERNEL, CRST_ALLOC_ORDER);
if (!page) if (!page)
goto out_free; goto out_free;
@@ -214,7 +214,7 @@ static void gmap_free(struct gmap *gmap)
*/ */
struct gmap *gmap_get(struct gmap *gmap) struct gmap *gmap_get(struct gmap *gmap)
{ {
atomic_inc(&gmap->ref_count); refcount_inc(&gmap->ref_count);
return gmap; return gmap;
} }
EXPORT_SYMBOL_GPL(gmap_get); EXPORT_SYMBOL_GPL(gmap_get);
@@ -227,7 +227,7 @@ EXPORT_SYMBOL_GPL(gmap_get);
*/ */
void gmap_put(struct gmap *gmap) 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); gmap_free(gmap);
} }
EXPORT_SYMBOL_GPL(gmap_put); EXPORT_SYMBOL_GPL(gmap_put);
@@ -1594,7 +1594,7 @@ static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce,
continue; continue;
if (!sg->initialized) if (!sg->initialized)
return ERR_PTR(-EAGAIN); return ERR_PTR(-EAGAIN);
atomic_inc(&sg->ref_count); refcount_inc(&sg->ref_count);
return sg; return sg;
} }
return NULL; 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); list_add(&new->list, &parent->children);
if (asce & _ASCE_REAL_SPACE) { if (asce & _ASCE_REAL_SPACE) {
/* nothing to protect, return right away */ /* nothing to protect, return right away */