Re: [Outreachy kernel] [PATCH 1/5] include: linux: pid: Update documentation.

[Julia Lawall <julia.lawall@lip6.fr>]

On Sun, 26 Mar 2017, Varsha Rao wrote:

> This patch adds comments to update documentation. Also remove extra
> space between full stop and and new sentence, of existing comments.

Actually, at least in American English, a period should be followed by two
spaces.  Like in this email :)

julia

>
> Signed-off-by: Varsha Rao <rvarsha016@gmail.com>
> ---
>  include/linux/pid.h | 43 ++++++++++++++++++++++++++++++++-----------
>  1 file changed, 32 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/pid.h b/include/linux/pid.h
> index 4d17931..c2bea47 100644
> --- a/include/linux/pid.h
> +++ b/include/linux/pid.h
> @@ -5,32 +5,32 @@
>
>  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 */
>  };
>
>  /*
>   * What is struct pid?
>   *
>   * A struct pid is the kernel's internal notion of a process identifier.
> - * It refers to individual tasks, process groups, and sessions.  While
> + * It refers to individual tasks, process groups, and sessions. While
>   * there are processes attached to it the struct pid lives in a hash
>   * table, so it and then the processes that it refers to can be found
> - * quickly from the numeric pid value.  The attached processes may be
> + * quickly from the numeric pid value. The attached processes may be
>   * quickly accessed by following pointers from struct pid.
>   *
>   * Storing pid_t values in the kernel and referring to them later has a
> - * problem.  The process originally with that pid may have exited and the
> + * problem. The process originally with that pid may have exited and the
>   * pid allocator wrapped, and another process could have come along
>   * and been assigned that pid.
>   *
>   * Referring to user space processes by holding a reference to struct
> - * task_struct has a problem.  When the user space process exits
> - * the now useless task_struct is still kept.  A task_struct plus a
> - * stack consumes around 10K of low kernel memory.  More precisely
> - * this is THREAD_SIZE + sizeof(struct task_struct).  By comparison
> + * task_struct has a problem. When the user space process exits
> + * the now useless task_struct is still kept. A task_struct plus a
> + * stack consumes around 10K of low kernel memory. More precisely
> + * this is THREAD_SIZE + sizeof(struct task_struct). By comparison
>   * a struct pid is about 64 bytes.
>   *
>   * Holding a reference to struct pid solves both of these problems.
> @@ -45,6 +45,10 @@ enum pid_type
>   * 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.
> + *
> + * @nr: Pid value.
> + * @ns: Represents the namespace to which pid value belongs.
> + * @pid_chain: Hash chain.
>   */
>
>  struct upid {
> @@ -54,6 +58,15 @@ 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 +79,20 @@ struct pid
>
>  extern struct pid init_struct_pid;
>
> +/*
> + * struct pid_link is used for 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
>
> --
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