[Devel] [PATCH vz10 v6 1/2] ve: Introduce task_pid_ve_nr() helper

[Konstantin Khorenko]

From: Aleksei Oladko <aleksey.oladko at virtuozzo.com>

The new helper returns pid in root pidns of VE.

https://virtuozzo.atlassian.net/browse/VSTOR-119875

Signed-off-by: Aleksei Oladko <aleksey.oladko at virtuozzo.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

Feature: ve: ve generic structures

---
v4: used task_ve guard helpers
v5:
  - ve_ns has been renamed to ve_nsproxy in order not to mess with VE namespace
  - use new, bright and shiny __free(put_ve) attribute
  - added a comment why we don't check ve returned by get_task_ve() for NULL
v6: moved defining of the put_ve FREE attribute inside CONFIG_VE,
    had to do that because it should be done between function declaration and
    attribute usage
---
 include/linux/ve.h | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/include/linux/ve.h b/include/linux/ve.h
index 0fbc4c45525fc..cd0e855d38f18 100644
--- a/include/linux/ve.h
+++ b/include/linux/ve.h
@@ -21,6 +21,7 @@
 #include <asm/vdso.h>
 #include <linux/time_namespace.h>
 #include <linux/binfmts.h>
+#include <linux/pid.h>
 
 struct nsproxy;
 struct user_namespace;
@@ -179,6 +180,8 @@ void cgroot_ve_cleanup_ra_data(struct cgroup_root *cgroot);
 extern struct ve_struct *get_ve(struct ve_struct *ve);
 extern void put_ve(struct ve_struct *ve);
 
+DEFINE_FREE(put_ve, struct ve_struct *, if (_T) put_ve(_T))
+
 static inline struct ve_struct *task_ve(struct task_struct *task)
 {
 	return READ_ONCE(task->task_ve);
@@ -202,6 +205,24 @@ static inline struct ve_struct *css_to_ve(struct cgroup_subsys_state *css)
 
 extern struct cgroup_subsys_state *ve_get_init_css(struct ve_struct *ve, int subsys_id);
 
+static inline pid_t task_pid_ve_nr(struct task_struct *tsk)
+{
+	struct nsproxy *ve_nsproxy;
+	struct ve_struct *ve __free(put_ve) = get_task_ve(tsk);
+	pid_t pid;
+
+	rcu_read_lock();
+	/* get_task_ve() always returns non-NULL when CONFIG_VE is enabled */
+	ve_nsproxy = rcu_dereference(ve->ve_nsproxy);
+	if (ve_nsproxy)
+		pid = task_pid_nr_ns(tsk, ve_nsproxy->pid_ns_for_children);
+	else
+		pid = task_pid_nr(tsk);
+	rcu_read_unlock();
+
+	return pid;
+}
+
 static inline struct time_namespace *ve_get_time_ns(struct ve_struct *ve)
 {
 	struct nsproxy *ve_nsproxy;
@@ -259,6 +280,8 @@ extern bool is_ve_init_net(const struct net *net);
 #define get_ve(ve)	((void)(ve), NULL)
 #define put_ve(ve)	do { (void)(ve); } while (0)
 
+DEFINE_FREE(put_ve, struct ve_struct *, if (_T) put_ve(_T))
+
 static inline struct ve_struct *task_ve(struct task_struct *task)
 {
 	return NULL;
@@ -323,6 +346,4 @@ static inline int ve_get_cpu_avenrun(struct ve_struct *ve, unsigned long *avenru
 static inline int ve_get_cpu_stat(struct ve_struct *ve, struct kernel_cpustat *kstat) { return -ENOSYS; }
 #endif
 
-DEFINE_FREE(put_ve, struct ve_struct *, if (_T) put_ve(_T))
-
 #endif /* _LINUX_VE_H */
-- 
2.43.5