flex_array: flex_array_prealloc takes a number of elements, not an end

Change flex_array_prealloc to take the number of elements for which space
should be allocated instead of the last (inclusive) element. Users
and documentation are updated accordingly.  flex_arrays got introduced before
they had users.  When folks started using it, they ended up needing a
different API than was coded up originally.  This swaps over to the API that
folks apparently need.

Based-on-patch-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Tested-by: Chris Richards <gizmo@giz-works.com>
Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: stable@kernel.org [2.6.38+]

4 files changed, 14 insertions, 11 deletions

diff --git a/Documentation/flexible-arrays.txt b/Documentation/flexible-arrays.txt
index cb8a3a00cc92..df904aec9904 100644
--- a/Documentation/flexible-arrays.txt
+++ b/Documentation/flexible-arrays.txt
@@ -66,10 +66,10 @@ trick is to ensure that any needed memory allocations are done before
 entering atomic context, using:
 
     int flex_array_prealloc(struct flex_array *array, unsigned int start,
-                            unsigned int end, gfp_t flags);
+                            unsigned int nr_elements, gfp_t flags);
 
 This function will ensure that memory for the elements indexed in the range
-defined by start and end has been allocated.  Thereafter, a
+defined by start and nr_elements has been allocated.  Thereafter, a
 flex_array_put() call on an element in that range is guaranteed not to
 block.
 
diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h
index 70e4efabe0fb..ebeb2f3ad068 100644
--- a/include/linux/flex_array.h
+++ b/include/linux/flex_array.h
@@ -61,7 +61,7 @@ struct flex_array {
 struct flex_array *flex_array_alloc(int element_size, unsigned int total,
                 gfp_t flags);
 int flex_array_prealloc(struct flex_array *fa, unsigned int start,
-                unsigned int end, gfp_t flags);
+                unsigned int nr_elements, gfp_t flags);
 void flex_array_free(struct flex_array *fa);
 void flex_array_free_parts(struct flex_array *fa);
 int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
diff --git a/lib/flex_array.c b/lib/flex_array.c
index c0ea40ba2082..0c33b24498ba 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -232,10 +232,10 @@ EXPORT_SYMBOL(flex_array_clear);
 
 /**
  * flex_array_prealloc - guarantee that array space exists
- * @fa:         the flex array for which to preallocate parts
- * @start:      index of first array element for which space is allocated
- * @end:        index of last (inclusive) element for which space is allocated
- * @flags:      page allocation flags
+ * @fa:                 the flex array for which to preallocate parts
+ * @start:              index of first array element for which space is allocated
+ * @nr_elements:        number of elements for which space is allocated
+ * @flags:              page allocation flags
  *
  * This will guarantee that no future calls to flex_array_put()
  * will allocate memory.  It can be used if you are expecting to
@@ -245,13 +245,16 @@ EXPORT_SYMBOL(flex_array_clear);
  * Locking must be provided by the caller.
  */
 int flex_array_prealloc(struct flex_array *fa, unsigned int start,
-                        unsigned int end, gfp_t flags)
+                        unsigned int nr_elements, gfp_t flags)
 {
         int start_part;
         int end_part;
         int part_nr;
+        unsigned int end;
         struct flex_array_part *part;
 
+        end = start + nr_elements - 1;
+
         if (start >= fa->total_nr_elements || end >= fa->total_nr_elements)
                 return -ENOSPC;
         if (elements_fit_in_base(fa))
diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 549120c56edd..102e9ec1b77a 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -545,7 +545,7 @@ static int policydb_index(struct policydb *p)
                 goto out;
 
         rc = flex_array_prealloc(p->type_val_to_struct_array, 0,
-                                 p->p_types.nprim - 1, GFP_KERNEL | __GFP_ZERO);
+                                 p->p_types.nprim, GFP_KERNEL | __GFP_ZERO);
         if (rc)
                 goto out;
 
@@ -562,7 +562,7 @@ static int policydb_index(struct policydb *p)
                         goto out;
 
                 rc = flex_array_prealloc(p->sym_val_to_name[i],
-                                         0, p->symtab[i].nprim - 1,
+                                         0, p->symtab[i].nprim,
                                          GFP_KERNEL | __GFP_ZERO);
                 if (rc)
                         goto out;
@@ -2439,7 +2439,7 @@ int policydb_read(struct policydb *p, void *fp)
                 goto bad;
 
         /* preallocate so we don't have to worry about the put ever failing */
-        rc = flex_array_prealloc(p->type_attr_map_array, 0, p->p_types.nprim - 1,
+        rc = flex_array_prealloc(p->type_attr_map_array, 0, p->p_types.nprim,
                                  GFP_KERNEL | __GFP_ZERO);
         if (rc)
                 goto bad;