[PATCH v3 1/5] include: linux: pid: Update documentation.

[Varsha Rao <rvarsha016@gmail.com>]

This patch adds comments to update documentation.

Signed-off-by: Varsha Rao <rvarsha016@gmail.com>
---
Changes in v3:
- Changed comment style.

Changes in v2:
- Keep original comments.
- Modified commit message.

 include/linux/pid.h | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/include/linux/pid.h b/include/linux/pid.h
index 4d17931..ea90c1f 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -5,10 +5,10 @@
 
 enum pid_type
 {
-	PIDTYPE_PID,
-	PIDTYPE_PGID,
-	PIDTYPE_SID,
-	PIDTYPE_MAX
+	PIDTYPE_PID, /* Process ID */
+	PIDTYPE_PGID, /* Process group ID */
+	PIDTYPE_SID, /* Process session ID */
+	PIDTYPE_MAX /* Number of ID types */
 };
 
 /*
@@ -42,11 +42,15 @@ enum pid_type
 
 
 /*
+ * struct upid - Get PID for particular namespace.
+ * @nr: Pid value.
+ * @ns: Represents the namespace to which pid value belongs.
+ * @pid_chain: Hash chain.
+ *
  * struct upid is used to get the id of the struct pid, as it is
  * seen in particular namespace. Later the struct pid is found with
  * find_pid_ns() using the int nr and struct pid_namespace *ns.
  */
-
 struct upid {
 	/* Try to keep pid_chain in the same cacheline as nr for find_vpid */
 	int nr;
@@ -54,6 +58,14 @@ struct upid {
 	struct hlist_node pid_chain;
 };
 
+/*
+ * struct pid
+ * @count: Reference counter.
+ * @level: Number of namespaces in which the process is visible.
+ * @tasks: Lists of tasks.
+ * @rcu: RCU helper.
+ * @numbers: Instance of upid for each level.
+ */
 struct pid
 {
 	atomic_t count;
@@ -66,12 +78,21 @@ struct pid
 
 extern struct pid init_struct_pid;
 
+/*
+ * struct pid_link - Per process linkage into hash tables.
+ * @node: List element.
+ * @pid: Pointer to the struct pid of the process.
+ */
 struct pid_link
 {
 	struct hlist_node node;
 	struct pid *pid;
 };
 
+/*
+ * get_pid() - Checks availability of process id and if available assigns
+ * process ID.
+ */
 static inline struct pid *get_pid(struct pid *pid)
 {
 	if (pid)
-- 
2.9.3