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authorKristian Hoegsberg <krh@redhat.com>2007-07-15 23:37:24 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-16 09:05:34 -0700
commit96d7fa421e6424ad9ef6d1d039375dc2edb63fe8 (patch)
treeba8a8200bda4576e1e4dcce2ff27a7a7a94723a2 /lib/idr.c
parentde7d4f0e1172a72277d660fa0be59654ea02bed0 (diff)
downloadlinux-2.6.38-lt-ux500-96d7fa421e6424ad9ef6d1d039375dc2edb63fe8.tar.gz
lib: add idr_for_each()
This patch adds an iterator function for the idr data structure. Compared to just iterating through the idr with an integer and idr_find, this iterator is (almost, but not quite) linear in the number of elements, as opposed to the number of integers in the range covered by the idr. This makes a difference for sparse idrs, but more importantly, it's a nicer way to iterate through the elements. The drm subsystem is moving to idr for tracking contexts and drawables, and with this change, we can use the idr exclusively for tracking these resources. [akpm@linux-foundation.org: fix comment] Signed-off-by: Kristian Hoegsberg <krh@redhat.com> Cc: Tejun Heo <htejun@gmail.com> Cc: Dave Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/idr.c')
-rw-r--r--lib/idr.c55
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/idr.c b/lib/idr.c
index b98f01a2eb9..d29da6159da 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -437,6 +437,61 @@ void *idr_find(struct idr *idp, int id)
EXPORT_SYMBOL(idr_find);
/**
+ * idr_for_each - iterate through all stored pointers
+ * @idp: idr handle
+ * @fn: function to be called for each pointer
+ * @data: data passed back to callback function
+ *
+ * Iterate over the pointers registered with the given idr. The
+ * callback function will be called for each pointer currently
+ * registered, passing the id, the pointer and the data pointer passed
+ * to this function. It is not safe to modify the idr tree while in
+ * the callback, so functions such as idr_get_new and idr_remove are
+ * not allowed.
+ *
+ * We check the return of @fn each time. If it returns anything other
+ * than 0, we break out and return that value.
+ *
+ * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove().
+ */
+int idr_for_each(struct idr *idp,
+ int (*fn)(int id, void *p, void *data), void *data)
+{
+ int n, id, max, error = 0;
+ struct idr_layer *p;
+ struct idr_layer *pa[MAX_LEVEL];
+ struct idr_layer **paa = &pa[0];
+
+ n = idp->layers * IDR_BITS;
+ p = idp->top;
+ max = 1 << n;
+
+ id = 0;
+ while (id < max) {
+ while (n > 0 && p) {
+ n -= IDR_BITS;
+ *paa++ = p;
+ p = p->ary[(id >> n) & IDR_MASK];
+ }
+
+ if (p) {
+ error = fn(id, (void *)p, data);
+ if (error)
+ break;
+ }
+
+ id += 1 << n;
+ while (n < fls(id)) {
+ n += IDR_BITS;
+ p = *--paa;
+ }
+ }
+
+ return error;
+}
+EXPORT_SYMBOL(idr_for_each);
+
+/**
* idr_replace - replace pointer for given id
* @idp: idr handle
* @ptr: pointer you want associated with the id