sched.h: move pid helpers to pid.h

This is needed for killing the sched.h dependency on rcupdate.h, and
pid.h is a better place for this code anyways.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 125 insertions, 0 deletions

diff --git a/include/linux/pid.h b/include/linux/pid.h
index f254c3a45b9b..395cacce1179 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -4,7 +4,9 @@
 
 #include <linux/pid_types.h>
 #include <linux/rculist.h>
+#include <linux/rcupdate.h>
 #include <linux/refcount.h>
+#include <linux/sched.h>
 #include <linux/wait.h>
 
 /*
@@ -204,4 +206,127 @@ pid_t pid_vnr(struct pid *pid);
 		}							\
 		task = tg___;						\
 	} while_each_pid_task(pid, type, task)
+
+static inline struct pid *task_pid(struct task_struct *task)
+{
+	return task->thread_pid;
+}
+
+/*
+ * the helpers to get the task's different pids as they are seen
+ * from various namespaces
+ *
+ * task_xid_nr()     : global id, i.e. the id seen from the init namespace;
+ * task_xid_vnr()    : virtual id, i.e. the id seen from the pid namespace of
+ *                     current.
+ * task_xid_nr_ns()  : id seen from the ns specified;
+ *
+ * see also pid_nr() etc in include/linux/pid.h
+ */
+pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, struct pid_namespace *ns);
+
+static inline pid_t task_pid_nr(struct task_struct *tsk)
+{
+	return tsk->pid;
+}
+
+static inline pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+	return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
+}
+
+static inline pid_t task_pid_vnr(struct task_struct *tsk)
+{
+	return __task_pid_nr_ns(tsk, PIDTYPE_PID, NULL);
+}
+
+
+static inline pid_t task_tgid_nr(struct task_struct *tsk)
+{
+	return tsk->tgid;
+}
+
+/**
+ * pid_alive - check that a task structure is not stale
+ * @p: Task structure to be checked.
+ *
+ * Test if a process is not yet dead (at most zombie state)
+ * If pid_alive fails, then pointers within the task structure
+ * can be stale and must not be dereferenced.
+ *
+ * Return: 1 if the process is alive. 0 otherwise.
+ */
+static inline int pid_alive(const struct task_struct *p)
+{
+	return p->thread_pid != NULL;
+}
+
+static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+	return __task_pid_nr_ns(tsk, PIDTYPE_PGID, ns);
+}
+
+static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
+{
+	return __task_pid_nr_ns(tsk, PIDTYPE_PGID, NULL);
+}
+
+
+static inline pid_t task_session_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+	return __task_pid_nr_ns(tsk, PIDTYPE_SID, ns);
+}
+
+static inline pid_t task_session_vnr(struct task_struct *tsk)
+{
+	return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);
+}
+
+static inline pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+	return __task_pid_nr_ns(tsk, PIDTYPE_TGID, ns);
+}
+
+static inline pid_t task_tgid_vnr(struct task_struct *tsk)
+{
+	return __task_pid_nr_ns(tsk, PIDTYPE_TGID, NULL);
+}
+
+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);
+}
+
+/* Obsolete, do not use: */
+static inline pid_t task_pgrp_nr(struct task_struct *tsk)
+{
+	return task_pgrp_nr_ns(tsk, &init_pid_ns);
+}
+
+/**
+ * is_global_init - check if a task structure is init. Since init
+ * is free to have sub-threads we need to check tgid.
+ * @tsk: Task structure to be checked.
+ *
+ * Check if a task structure is the first user space task the kernel created.
+ *
+ * Return: 1 if the task structure is init. 0 otherwise.
+ */
+static inline int is_global_init(struct task_struct *tsk)
+{
+	return task_tgid_nr(tsk) == 1;
+}
+
 #endif /* _LINUX_PID_H */