idr: make idr_get_new* rcu-safe

Make the idr_get_new* routines rcu-safe.

Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Reviewed-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Jim Houston <jim.houston@comcast.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 5 deletions

diff --git a/lib/idr.c b/lib/idr.c
index 80ba06f29d36..44ab3b2a4eba 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -6,6 +6,8 @@
  * Modified by George Anzinger to reuse immediately and to use
  * find bit instructions.  Also removed _irq on spinlocks.
  *
+ * Modified by Nadia Derbey to make it RCU safe.
+ *
  * Small id to pointer translation service.
  *
  * It uses a radix tree like structure as a sparse array indexed
@@ -96,7 +98,7 @@ static void idr_mark_full(struct idr_layer **pa, int id)
  * @gfp_mask:   memory allocation flags
  *
  * This function should be called prior to locking and calling the
- * following function.  It preallocates enough memory to satisfy
+ * idr_get_new* functions. It preallocates enough memory to satisfy
  * the worst possible allocation.
  *
  * If the system is REALLY out of memory this function returns 0,
@@ -170,7 +172,7 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
                         new = get_from_free_list(idp);
                         if (!new)
                                 return -1;
-                        p->ary[m] = new;
+                        rcu_assign_pointer(p->ary[m], new);
                         p->count++;
                 }
                 pa[l--] = p;
@@ -226,7 +228,7 @@ build_up:
                         __set_bit(0, &new->bitmap);
                 p = new;
         }
-        idp->top = p;
+        rcu_assign_pointer(idp->top, p);
         idp->layers = layers;
         v = sub_alloc(idp, &id, pa);
         if (v == IDR_NEED_TO_GROW)
@@ -245,7 +247,8 @@ static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
                  * Successfully found an empty slot.  Install the user
                  * pointer and mark the slot full.
                  */
-                pa[0]->ary[id & IDR_MASK] = (struct idr_layer *)ptr;
+                rcu_assign_pointer(pa[0]->ary[id & IDR_MASK],
+                                (struct idr_layer *)ptr);
                 pa[0]->count++;
                 idr_mark_full(pa, id);
         }
@@ -710,7 +713,8 @@ int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
                         return -EAGAIN;
 
                 memset(bitmap, 0, sizeof(struct ida_bitmap));
-                pa[0]->ary[idr_id & IDR_MASK] = (void *)bitmap;
+                rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK],
+                                (void *)bitmap);
                 pa[0]->count++;
         }