The commit is pushed to "branch-rh7-3.10.0-327.4.5.vz7.11.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.4.5.vz7.11.4
------>
commit 4738d245d27354b82ffbb820973ad436fca6a464
Author: Stanislav Kinsburskiy <[email protected]>
Date: Fri Feb 19 15:37:05 2016 +0400
ve: move ve-related checks to separated function from ve_can_attach()
Patch series description:
Inspired by https://jira.sw.ru/browse/PSBM-44143
Function ve_can_attach is a mess: it's unclear, review is complicated, some
of
the hunks are simply copied without explanation, some - old code without
comments and clear understanding of the introductions reasons.
Wha't even worse is that no error messages are printed in case of failure.
This series tries to rework this code to make it clearer by splitting
independent parts, adding comments and error messages.
v2:
1) Check to empty process group returned back.
2) Error messages patch merged with corresponding code introducing ones.
=======================
This patch description:
Patch moves all the ve-related checks to another new helper function
ve_is_attachable().
Signed-off-by: Stanislav Kinsburskiy <[email protected]>
Reviewed-by: Cyrill Gorcunov <[email protected]>
---
kernel/ve/ve.c | 53 ++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 38 insertions(+), 15 deletions(-)
diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
index 67783a5..84fd806 100644
--- a/kernel/ve/ve.c
+++ b/kernel/ve/ve.c
@@ -722,6 +722,43 @@ static bool ve_task_can_attach(struct cgroup *cg, struct
cgroup_taskset *tset)
return true;
}
+static int ve_is_attachable(struct cgroup *cg, struct cgroup_taskset *tset)
+{
+ struct task_struct *task = cgroup_taskset_first(tset);
+ struct ve_struct *ve = cgroup_ve(cg);
+
+ if (ve->is_running)
+ return 0;
+
+ if (!ve->veid) {
+ pr_err_ratelimited("ve_cgroup#%s: container's veid is not
set\n",
+ cg->name->name);
+ return -EINVAL;
+ }
+
+ if (task->flags & PF_KTHREAD) {
+ /* Paranoia check: allow to attach kthread only, if cgroup is
+ * not empty.
+ * This check is required for kthreadd, which is created on CT
+ * start.
+ */
+ if (nr_threads_ve(ve))
+ return 0;
+ pr_err_ratelimited("ve_cgroup#%s: can't attach kthread - empty
group\n",
+ cg->name->name);
+ } else {
+ /* In case of generic task only one is allowed to enter to
+ * non-running container: init.
+ */
+ if (nr_threads_ve(ve) == 0)
+ return 0;
+ pr_err_ratelimited("ve_cgroup#%s: can't attach more than 1 task
to "
+ "non-running container\n",
+ cg->name->name);
+ }
+ return -EINVAL;
+}
+
static void ve_destroy(struct cgroup *cg)
{
struct ve_struct *ve = cgroup_ve(cg);
@@ -740,24 +777,10 @@ static void ve_destroy(struct cgroup *cg)
static int ve_can_attach(struct cgroup *cg, struct cgroup_taskset *tset)
{
- struct ve_struct *ve = cgroup_ve(cg);
-
- if (!ve->veid)
- return -ENOENT;
-
if (!ve_task_can_attach(cg, tset))
return -EINVAL;
- /*
- * XXX Still permit attaching kernel threads
- * for this container. Wonder if we really need it,
- * looks like some legacy code chunk.
- */
- if (!ve->is_running && (ve->ve_ns || nr_threads_ve(ve))) {
- if (!(cgroup_taskset_first(tset)->flags & PF_KTHREAD))
- return -EPIPE;
- }
- return 0;
+ return ve_is_attachable(cg, tset);
}
static void ve_update_cpuid_faulting(void *dummy)
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