Messages in this thread Patch in this message | | | Date | Thu, 29 Mar 2012 09:26:20 -0700 | From | Tejun Heo <> | Subject | [PATCH for-3.4-fixes] cgroup: cgroup_attach_task() could return -errno after success |
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61d1d219c4 "cgroup: remove extra calls to find_existing_css_set" made cgroup_task_migrate() return void. An unfortunate side effect was that cgroup_attach_task() was depending on that function's return value to clear its @retval on the success path. On cgroup mounts without any subsystem with ->can_attach() callback, cgroup_attach_task() ended up returning @retval without initializing it on success.
For some reason, gcc failed to warn about it and it didn't cause cgroup_attach_task() to return non-zero value in many cases, probably due to difference in register allocation. When the problem materializes, systemd fails to populate /systemd cgroup mount and fails to boot.
Fix it by initializing @retval to zero on declaration.
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jiri Kosina <jkosina@suse.cz> LKML-Reference: <alpine.LNX.2.00.1203282354440.25526@pobox.suse.cz> --- Jiri, can you please confirm the fix?
Thanks.
kernel/cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index f4ea4b6..ed64cca 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1883,7 +1883,7 @@ static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, */ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) { - int retval; + int retval = 0; struct cgroup_subsys *ss, *failed_ss = NULL; struct cgroup *oldcgrp; struct cgroupfs_root *root = cgrp->root;
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