Currently if we add a new TASKSTATS_ constant, we will chanage all
CGROUPSTATS_ contants and break backward compatibility.

Signed-off-by: Andrey Vagin <avagin@openvz.org>

Signed-off-by: Andrey Vagin <avagin@openvz.org>

This function will be used in task_diag.

Signed-off-by: Andrey Vagin <avagin@openvz.org>

It will be more convenient when this function will be used in
task_diag.

Signed-off-by: Andrey Vagin <avagin@openvz.org>

It's going to be used in task_diag

The task-diag interface allows to get information about running
processes (roughly same info that is now available from /proc/PID/*
files). Compared to /proc/PID/*, it is faster, more flexible and
provides data in a binary format.

Task-diag was created using the basic idea of socket_diag.

Here is the /proc/task-diag file, which operates based on the following
principles:

* Transactional: write request, read response
* Netlink message format (same as used by sock_diag; binary and extendable)

A request messages is described by the task_diag_pid structure:
struct task_diag_pid {
	__u64   show_flags;
	__u64   dump_strategy;

	__u32   pid;
};

A respone is a set of netlink messages. Each message describes one task.
All task properties are divided on groups. A message contains the
TASK_DIAG_PID group, and other groups if they have been requested in
show_flags. For example, if show_flags contains TASK_DIAG_SHOW_BASE, a
response will contain the TASK_DIAG_CRED group which is described by the
task_diag_creds structure.

struct task_diag_base {
	__u32   tgid;
	__u32   pid;
	__u32   ppid;
	__u32   tpid;
	__u32   sid;
	__u32   pgid;
	__u8    state;
	char    comm[TASK_DIAG_COMM_LEN];
};

The dump_strategy field will be used in following patches to request
information for a group of processes.

v2: A few changes from David Ahern
    Use a consistent name
    Add max attr enum
    task diag: Send pid as u32
    Change _MSG/msg references to base
    Fix 8-byte alignment

v3: take pid namespace from scm credentials. There is a pid of a process
which sent an request. If we need to get information from another
namespace, we can set pid in scm of a process from this namespaces.

v4: use a transaction file instead of netlink

Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>

A response is represented by the task_diag_creds structure:

struct task_diag_creds {
   struct task_diag_caps cap_inheritable;
   struct task_diag_caps cap_permitted;
   struct task_diag_caps cap_effective;
   struct task_diag_caps cap_bset;

   __u32 uid;
   __u32 euid;
   __u32 suid;
   __u32 fsuid;
   __u32 gid;
   __u32 egid;
   __u32 sgid;
   __u32 fsgid;
};

This group is optional and it's filled only if show_flags contains
TASK_DIAG_SHOW_CRED.

Signed-off-by: Andrey Vagin <avagin@openvz.org>

v2: Fixes from David Ahern
* Fix 8-byte alignment
* Change implementation of DIAG_VMA attribute:

This patch puts the filename into the task_diag_vma struct and
converts TASK_DIAG_VMA attribute into a series of task_diag_vma.
Now is there is a single TASK_DIAG_VMA attribute that is parsed
as:

| struct task_diag_vma | filename | ...

Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>

Now we can dump all task or children, threads of a specified task.
It's an example how this interface can be expanded for different
use-cases.

v2: Fixes from David Ahern
Add missing break in iter_stop
Fix 8-byte alignment issues

Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>

threads of a process share the same VMAs, so when dumping all threads
for all processes only push vma data for group leader.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>

If all information about a process don't fit in a message, it's marked
by the TASK_DIAG_FLAG_CONT flag and the next message will describe the
same process.

Signed-off-by: Andrey Vagin <avagin@openvz.org>

Here are two test (example) programs.

task_diag - request information for two processes.
test_diag_all - request information about all processes

v2: Fixes from David Ahern:
    * task_diag: Fix 8-byte alignment for vma and vma_stats

Signed-off-by: Andrey Vagin <avagin@openvz.org>

Add option to fork threads as well as processes.
Make the sleep time configurable too so that spawned
tasks exit on their own.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>

pos should be loff_t type. It's might be fine to truncate it
to unsigned int in this case, but it's better not to.
E.g. see 9f6e963 ("proc: fix ->f_pos overflows in first_tid()")

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>

Just to be safe. If truncation to unsigned int is fine it should be a
separate patch

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>

…DIAG_STAT

nice and priority are computed but not used.

Signe-off-by: Marc Titinger <marc.titinger@magnetimarelli.com>