[PATCH v3.5-rc1] blkcg: fix blkg_alloc() failure path

From: Tejun Heo
Date: Mon Jun 04 2012 - 02:21:15 EST


When policy data allocation fails in the middle, blkg_alloc() invokes
blkg_free() to destroy the half constructed blkg. This ends up
calling pd_exit_fn() on policy datas which didn't go through
pd_init_fn(). Fix it by making blkg_alloc() call pd_init_fn()
immediately after each policy data allocation.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Acked-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
Jens, this was posted as part of "block: implement per-blkg request
allocation" patchset[1] but should be applied as fix on v3.5-rc1.

[1] http://thread.gmane.org/gmane.linux.kernel.containers/23159/focus=2007

block/blk-cgroup.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -125,12 +125,8 @@ static struct blkcg_gq *blkg_alloc(struc

blkg->pd[i] = pd;
pd->blkg = blkg;
- }
-
- /* invoke per-policy init */
- for (i = 0; i < BLKCG_MAX_POLS; i++) {
- struct blkcg_policy *pol = blkcg_policy[i];

+ /* invoke per-policy init */
if (blkcg_policy_enabled(blkg->q, pol))
pol->pd_init_fn(blkg);
}
--
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