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: Richard Guy Briggs <rgb@redhat.com>
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@ -1561,6 +1561,24 @@ static inline pid_t task_tgid_vnr(struct task_struct *tsk)
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}
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static int pid_alive(const struct task_struct *p);
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static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)
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{
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pid_t pid = 0;
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rcu_read_lock();
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if (pid_alive(tsk))
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pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
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rcu_read_unlock();
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return pid;
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}
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static inline pid_t task_ppid_nr(const struct task_struct *tsk)
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{
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return task_ppid_nr_ns(tsk, &init_pid_ns);
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}
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static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
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struct pid_namespace *ns)
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{
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@ -1600,7 +1618,7 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk)
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*
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* Return: 1 if the process is alive. 0 otherwise.
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*/
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static inline int pid_alive(struct task_struct *p)
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static inline int pid_alive(const struct task_struct *p)
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{
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return p->pids[PIDTYPE_PID].pid != NULL;
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}
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