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pid: get pid_t ppid of task in init_pid_ns 

commit ad36d28293 upstream.

Added the functions task_ppid_nr_ns() and task_ppid_nr() to abstract the lookup
of the PPID (real_parent's pid_t) of a process, including rcu locking, in the
arbitrary and init_pid_ns.
This provides an alternative to sys_getppid(), which is relative to the child
process' pid namespace.

(informed by ebiederman's 6c621b7e)
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Richard Guy Briggs 2013-08-15 18:05:12 -04:00 committed by Greg Kroah-Hartman
parent be57abca40
commit 6960029959
1 changed files with 19 additions and 1 deletions
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20
include/linux/sched.h
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@ -1688,6 +1688,24 @@ static inline pid_t task_tgid_vnr(struct task_struct *tsk)
}
static int pid_alive(const struct task_struct *p);
static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)
{
pid_t pid = 0;
rcu_read_lock();
if (pid_alive(tsk))
pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
rcu_read_unlock();
return pid;
}
static inline pid_t task_ppid_nr(const struct task_struct *tsk)
{
return task_ppid_nr_ns(tsk, &init_pid_ns);
}
static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
struct pid_namespace *ns)
{
@ -1727,7 +1745,7 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk)
*
* Return: 1 if the process is alive. 0 otherwise.
*/
static inline int pid_alive(struct task_struct *p)
static inline int pid_alive(const struct task_struct *p)
{
return p->pids[PIDTYPE_PID].pid != NULL;
}