Commit ad36d282 authored by Richard Guy Briggs's avatar Richard Guy Briggs Committed by Eric Paris

pid: get pid_t ppid of task in init_pid_ns

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: stable@vger.kernel.org
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarRichard Guy Briggs <rgb@redhat.com>
parent 4a3eb726
...@@ -1561,6 +1561,24 @@ static inline pid_t task_tgid_vnr(struct task_struct *tsk) ...@@ -1561,6 +1561,24 @@ 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, static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
struct pid_namespace *ns) struct pid_namespace *ns)
{ {
...@@ -1600,7 +1618,7 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk) ...@@ -1600,7 +1618,7 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk)
* *
* Return: 1 if the process is alive. 0 otherwise. * 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; return p->pids[PIDTYPE_PID].pid != NULL;
} }
......
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