On 08.08.19 09:18, Chuhong Yuan wrote: > 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. > > Signed-off-by: Chuhong Yuan <[email protected]> > --- > arch/s390/include/asm/gmap.h | 4 +++- > arch/s390/mm/gmap.c | 10 +++++----- > 2 files changed, 8 insertions(+), 6 deletions(-) > > diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h > index fcbd638fb9f4..37f96b6f0e61 100644 > --- a/arch/s390/include/asm/gmap.h > +++ b/arch/s390/include/asm/gmap.h > @@ -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; > diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c > index 39c3a6e3d262..cd8e03f04d6d 100644 > --- a/arch/s390/mm/gmap.c > +++ b/arch/s390/mm/gmap.c > @@ -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 */ >
Reviewed-by: David Hildenbrand <[email protected]> -- Thanks, David / dhildenb
