commit 88be7b4be4aa17c88247e162bdd7577ea79db94f
author Kevin Wolf <kwolf@redhat.com> Fri May 20 18:49:07 2016 +0200
committer Kevin Wolf <kwolf@redhat.com> Wed May 25 19:04:10 2016 +0200
tree cec7d9da5079f6dba0c65945925aedfd8c77267c
parent 287db79df8af8e31f18e262feb5e05103a09e4d4

block: Fix bdrv_next() memory leak

The bdrv_next() users all leaked the BdrvNextIterator after completing
the iteration. Simply changing bdrv_next() to free the iterator before
returning NULL at the end of list doesn't work because some callers exit
the loop before looking at all BDSes.

This patch moves the BdrvNextIterator from the heap to the stack of
the caller and switches to a bdrv_first()/bdrv_next() interface for
initialising the iterator.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>

block.c

diff --git a/block.c b/block.c
index 1205ef8..d287771 100644
--- a/block.c
+++ b/block.c
@@ -3195,9 +3195,9 @@
 {
     BlockDriverState *bs;
     Error *local_err = NULL;
-    BdrvNextIterator *it = NULL;
+    BdrvNextIterator it;
 
-    while ((it = bdrv_next(it, &bs)) != NULL) {
+    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         AioContext *aio_context = bdrv_get_aio_context(bs);
 
         aio_context_acquire(aio_context);
@@ -3239,11 +3239,11 @@
 int bdrv_inactivate_all(void)
 {
     BlockDriverState *bs = NULL;
-    BdrvNextIterator *it = NULL;
+    BdrvNextIterator it;
     int ret = 0;
     int pass;
 
-    while ((it = bdrv_next(it, &bs)) != NULL) {
+    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         aio_context_acquire(bdrv_get_aio_context(bs));
     }
 
@@ -3252,8 +3252,7 @@
      * the second pass sets the BDRV_O_INACTIVE flag so that no further write
      * is allowed. */
     for (pass = 0; pass < 2; pass++) {
-        it = NULL;
-        while ((it = bdrv_next(it, &bs)) != NULL) {
+        for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
             ret = bdrv_inactivate_recurse(bs, pass);
             if (ret < 0) {
                 goto out;
@@ -3262,8 +3261,7 @@
     }
 
 out:
-    it = NULL;
-    while ((it = bdrv_next(it, &bs)) != NULL) {
+    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         aio_context_release(bdrv_get_aio_context(bs));
     }
 
@@ -3753,10 +3751,10 @@
 bool bdrv_is_first_non_filter(BlockDriverState *candidate)
 {
     BlockDriverState *bs;
-    BdrvNextIterator *it = NULL;
+    BdrvNextIterator it;
 
     /* walk down the bs forest recursively */
-    while ((it = bdrv_next(it, &bs)) != NULL) {
+    for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         bool perm;
 
         /* try to recurse in this top level bs */