Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target...

[pandora-kernel.git] / lib / idr.c

diff --git a/lib/idr.c b/lib/idr.c
index 5cd6029..73f4d53 100644 (file)
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -137,8 +137,10 @@ static void idr_layer_rcu_free(struct rcu_head *head)
        kmem_cache_free(idr_layer_cache, layer);
 }
 
-static inline void free_layer(struct idr_layer *p)
+static inline void free_layer(struct idr *idr, struct idr_layer *p)
 {
+       if (idr->hint && idr->hint == p)
+               RCU_INIT_POINTER(idr->hint, NULL);
        call_rcu(&p->rcu_head, idr_layer_rcu_free);
 }
 
@@ -363,8 +365,12 @@ build_up:
  * @id and @pa are from a successful allocation from idr_get_empty_slot().
  * Install the user pointer @ptr and mark the slot full.
  */
-static void idr_fill_slot(void *ptr, int id, struct idr_layer **pa)
+static void idr_fill_slot(struct idr *idr, void *ptr, int id,
+                         struct idr_layer **pa)
 {
+       /* update hint used for lookup, cleared from free_layer() */
+       rcu_assign_pointer(idr->hint, pa[0]);
+
        rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], (struct idr_layer *)ptr);
        pa[0]->count++;
        idr_mark_full(pa, id);
@@ -397,7 +403,7 @@ int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
        if (rv < 0)
                return rv == -ENOMEM ? -EAGAIN : rv;
 
-       idr_fill_slot(ptr, rv, pa);
+       idr_fill_slot(idp, ptr, rv, pa);
        *id = rv;
        return 0;
 }
@@ -504,7 +510,7 @@ int idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask)
        if (unlikely(id > max))
                return -ENOSPC;
 
-       idr_fill_slot(ptr, id, pa);
+       idr_fill_slot(idr, ptr, id, pa);
        return id;
 }
 EXPORT_SYMBOL_GPL(idr_alloc);
@@ -541,14 +547,14 @@ static void sub_remove(struct idr *idp, int shift, int id)
                to_free = NULL;
                while(*paa && ! --((**paa)->count)){
                        if (to_free)
-                               free_layer(to_free);
+                               free_layer(idp, to_free);
                        to_free = **paa;
                        **paa-- = NULL;
                }
                if (!*paa)
                        idp->layers = 0;
                if (to_free)
-                       free_layer(to_free);
+                       free_layer(idp, to_free);
        } else
                idr_remove_warning(id);
 }
@@ -563,6 +569,7 @@ void idr_remove(struct idr *idp, int id)
        struct idr_layer *p;
        struct idr_layer *to_free;
 
+       /* see comment in idr_find_slowpath() */
        if (WARN_ON_ONCE(id < 0))
                return;
 
@@ -581,7 +588,7 @@ void idr_remove(struct idr *idp, int id)
                --idp->layers;
                to_free->count = 0;
                bitmap_clear(to_free->bitmap, 0, IDR_SIZE);
-               free_layer(to_free);
+               free_layer(idp, to_free);
        }
        while (idp->id_free_cnt >= MAX_IDR_FREE) {
                p = get_from_free_list(idp);
@@ -622,7 +629,7 @@ void __idr_remove_all(struct idr *idp)
                /* Get the highest bit that the above add changed from 0->1. */
                while (n < fls(id ^ bt_mask)) {
                        if (p)
-                               free_layer(p);
+                               free_layer(idp, p);
                        n += IDR_BITS;
                        p = *--paa;
                }
@@ -655,23 +662,19 @@ void idr_destroy(struct idr *idp)
 }
 EXPORT_SYMBOL(idr_destroy);
 
-/**
- * idr_find - return pointer for given id
- * @idp: idr handle
- * @id: lookup key
- *
- * Return the pointer given the id it has been registered with.  A %NULL
- * return indicates that @id is not valid or you passed %NULL in
- * idr_get_new().
- *
- * This function can be called under rcu_read_lock(), given that the leaf
- * pointers lifetimes are correctly managed.
- */
-void *idr_find(struct idr *idp, int id)
+void *idr_find_slowpath(struct idr *idp, int id)
 {
        int n;
        struct idr_layer *p;
 
+       /*
+        * If @id is negative, idr_find() used to ignore the sign bit and
+        * performed lookup with the rest of bits, which is weird and can
+        * lead to very obscure bugs.  We're now returning NULL for all
+        * negative IDs but just in case somebody was depending on the sign
+        * bit being ignored, let's trigger WARN_ON_ONCE() so that they can
+        * be detected and fixed.  WARN_ON_ONCE() can later be removed.
+        */
        if (WARN_ON_ONCE(id < 0))
                return NULL;
 
@@ -691,7 +694,7 @@ void *idr_find(struct idr *idp, int id)
        }
        return((void *)p);
 }
-EXPORT_SYMBOL(idr_find);
+EXPORT_SYMBOL(idr_find_slowpath);
 
 /**
  * idr_for_each - iterate through all stored pointers
@@ -821,6 +824,7 @@ void *idr_replace(struct idr *idp, void *ptr, int id)
        int n;
        struct idr_layer *p, *old_p;
 
+       /* see comment in idr_find_slowpath() */
        if (WARN_ON_ONCE(id < 0))
                return ERR_PTR(-EINVAL);