In this function we are making use of rq->clock right before the
update of the rq clock, let's just call update_rq_clock() just
before that to avoid using a stale rq clock value.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1365724262-20142-5-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

check_preempt_curr() of fair class needs an uptodate sched clock
value to update runtime stats of the current task of the target's rq.

When a task is woken up, activate_task() is usually called right before
ttwu_do_wakeup() unless the task is still in the runqueue. In the latter
case we need to update the rq clock explicitly because activate_task()
isn't here to do the job for us.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1365724262-20142-4-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Because we may update the execution time in

    sched_group_set_shares()->update_cfs_shares()->reweight_entity()->update_curr()

before reweighting the entity while setting the group shares and this requires
an uptodate version of the runqueue clock.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1365724262-20142-3-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Because the sched_class::put_prev_task() callback of rt and fair
classes are referring to the rq clock to update their runtime
statistics. There is a missing rq clock update from the CPU
hotplug notifier's entry point of the scheduler.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1365724262-20142-2-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

migration_call() will do all the things that update_runtime() does.
So let's remove it.

Furthermore, there is potential risk that the current code will catch
BUG_ON at line 689 of rt.c when do cpu hotplug while there are realtime
threads running because of enabling runtime twice while the rt_runtime
may already changed.
Signed-off-by: NNeil Zhang <zhangwm@marvell.com>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1365685499-26515-1-git-send-email-zhangwm@marvell.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

In autogroup_create(), a tg is allocated and added to the task_groups
list. If CONFIG_RT_GROUP_SCHED is set, this tg is then modified while on
the list, without locking. This can race with someone walking the list,
like __enable_runtime() during CPU unplug, and result in a use-after-free
bug.

To fix this, move sched_online_group(), which adds the tg to the list,
to the end of the autogroup_create() function after the modification.
Signed-off-by: NGerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1369411669-46971-2-git-send-email-gerald.schaefer@de.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

It is a few instructions more efficent to and slightly more
readable to use this_rq()-> instead of cpu_rq(smp_processor_id())-> .

Size comparison of kernel/sched/fair.o:

   text    data     bss     dec     hex filename
  27972     122      26   28120    6dd8 fair.o.before
  27956     122      26   28104    6dc8 fair.o.after
Signed-off-by: NNathan Zimmer <nzimmer@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1368116643-87971-1-git-send-email-nzimmer@sgi.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

These inlines are only used by kernel/sched/fair.c so they do
not need to be present in the main kernel/sched/sched.h file.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1366398650-31599-3-git-send-email-paul.gortmaker@windriver.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This large chunk of load calculation code can be easily divorced
from the main core.c scheduler file, with only a couple
prototypes and externs added to a kernel/sched header.

Some recent commits expanded the code and the documentation of
it, making it large enough to warrant separation.  For example,
see:

  556061b0, "sched/nohz: Fix rq->cpu_load[] calculations"
  5aaa0b7a, "sched/nohz: Fix rq->cpu_load calculations some more"
  5167e8d5, "sched/nohz: Rewrite and fix load-avg computation -- again"

More importantly, it helps reduce the size of the main
sched/core.c by yet another significant amount (~600 lines).
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1366398650-31599-2-git-send-email-paul.gortmaker@windriver.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

When BSD process accounting is enabled and logs information to a
filesystem which gets frozen, system easily becomes unusable because
each attempt to account process information blocks. Thus e.g. every task
gets blocked in exit.

It seems better to drop accounting information (which can already happen
when filesystem is running out of space) instead of locking system up.
So we just skip the write if the filesystem is frozen.
Reported-by: NNikola Ciprich <nikola.ciprich@linuxbox.cz>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The scheduler doesn't yet fully support environments
with a single task running without a periodic tick.

In order to ensure we still maintain the duties of scheduler_tick(),
keep at least 1 tick per second.

This makes sure that we keep the progression of various scheduler
accounting and background maintainance even with a very low granularity.
Examples include cpu load, sched average, CFS entity vruntime,
avenrun and events such as load balancing, amongst other details
handled in sched_class::task_tick().

This limitation will be removed in the future once we get
these individual items to work in full dynticks CPUs.
Suggested-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

Commit 0637e029
("nohz: Select wide RCU nocb for full dynticks") intended
to force CONFIG_RCU_NOCB_CPU_ALL=y when full dynticks is
enabled.

However this option is part of a choice menu and Kconfig's
"select" instruction has no effect on such targets.

Fix this by using reverse dependencies on the targets we
don't want instead.
Reviewed-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

Supply a function (proc_remove()) to remove a proc entry (and any subtree
rooted there) by proc_dir_entry pointer rather than by name and (optionally)
root dir entry pointer.  This allows us to eliminate all remaining pde->name
accesses outside of procfs.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NGrant Likely <grant.likely@linaro.or>
cc: linux-acpi@vger.kernel.org
cc: openipmi-developer@lists.sourceforge.net
cc: devicetree-discuss@lists.ozlabs.org
cc: linux-pci@vger.kernel.org
cc: netdev@vger.kernel.org
cc: netfilter-devel@vger.kernel.org
cc: alsa-devel@alsa-project.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Split the proc namespace stuff out into linux/proc_ns.h.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
cc: netdev@vger.kernel.org
cc: Serge E. Hallyn <serge.hallyn@ubuntu.com>
cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Supply accessor functions to set attributes in proc_dir_entry structs.

The following are supplied: proc_set_size() and proc_set_user().
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NMauro Carvalho Chehab <mchehab@redhat.com>
cc: linuxppc-dev@lists.ozlabs.org
cc: linux-media@vger.kernel.org
cc: netdev@vger.kernel.org
cc: linux-wireless@vger.kernel.org
cc: linux-pci@vger.kernel.org
cc: netfilter-devel@vger.kernel.org
cc: alsa-devel@alsa-project.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

If we allocate perf ring buffer with the size of single (user)
page, we will get memory corruption when releasing itin
rb_free_work function (for CONFIG_PERF_USE_VMALLOC option).

For single page sized ring buffer the page_order is -1 (because
nr_pages is 0). This needs to be recognized in the rb_free_work
function to release proper amount of pages.

Adding data_page_nr function that returns number of allocated
data pages. Customizing the rest of the code to use it.
Reported-by: NJan Stancek <jstancek@redhat.com>
Original-patch-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20130319143509.GA1128@krava.brq.redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Currently help message of /proc/sysrq-trigger highlight its
upper-case characters, like below:

      SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E)
      memory-full-oom-kill(F) kill-all-tasks(I) ...

this would confuse user trigger sysrq by upper-case character, which is
inconsistent with the real lower-case character registed key.

This inconsistent help message will also lead more confused when
26 upper-case letters put into use in future.

This patch fix power off sysrq key: "poweroff(o)"
Signed-off-by: Nzhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently help message of /proc/sysrq-trigger highlight its upper-case
characters, like below:

      SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E)
      memory-full-oom-kill(F) kill-all-tasks(I) ...

this would confuse user trigger sysrq by upper-case character, which is
inconsistent with the real lower-case character registed key.

This inconsistent help message will also lead more confused when
26 upper-case letters put into use in future.

This patch fix kgdb sysrq key: "debug(g)"
Signed-off-by: Nzhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The purpose of this patch is to allow privileged processes to set
their own per-memory memory-region fields:

      start_code, end_code, start_data, end_data, start_brk, brk,
      start_stack, arg_start, arg_end, env_start, env_end.

This functionality is needed by any application or package that needs to
reconstruct Linux processes, that is, to start them in any way other than
by means of an "execve()" from an executable file.  This includes:

1. Restoring processes from a checkpoint-file (by all potential
   user-level checkpointing packages, not only CRIU's).
2. Restarting processes on another node after process migration.
3. Starting duplicated copies of a running process (for reliability
   and high-availablity).
4. Starting a process from an executable format that is not supported
   by Linux, thus requiring a "manual execve" by a user-level utility.
5. Similarly, starting a process from a networked and/or crypted
   executable that, for confidentiality, licensing or other reasons,
   may not be written to the local file-systems.

The code that does that was already included in the Linux kernel by the
CRIU group, in the form of "prctl(PR_SET_MM)", but prior to this was
enclosed within their private "#ifdef CONFIG_CHECKPOINT_RESTORE", which is
normally disabled.  The patch removes those ifdefs.
Signed-off-by: NAmnon Shiloh <u3557@miso.sublimeip.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Macro FIX_SIZE is same as PAGE_ALIGN at present, so use PAGE_ALIGN
instead.

Thanks Andrew found this.
Signed-off-by: Nzhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It's better to place FIX_SIZE macro in relay.c, instead of relay.h
Signed-off-by: Nzhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently argument `actor' is never used in the relay reading path, so
remove it.
Signed-off-by: Nzhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Nliguang <lig.fnst@cn.fujitsu.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Nliguang <lig.fnst@cn.fujitsu.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move BITS_PER_PAGE from pid_namespace.c to pid_namespace.h, since we can
simplify the define PID_MAP_ENTRIES by using the BITS_PER_PAGE.

[akpm@linux-foundation.org: kernel/pid.c:54:1: warning: "BITS_PER_PAGE" redefined]
Signed-off-by: NRaphael S.Carvalho <raphael.scarv@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

find_next_offset() searches for an available "cleaned bit" in the
respective pid bitmap (page), so returns the offset if found, otherwise
it returns a value equals to BITS_PER_PAGE.

For example, suppose find_next_offset didn't find any available bit, so
there's no purpose to call mk_pid (Wasteful Cpu Cycles).

Therefore, I found it could be better to call mk_pid after the checking
(offset < BITS_PER_PAGE) returned sucessfully! Another point: If (offset
< BITS_PER_PAGE) results in a "failure", then mk_pid would be called
again afterwards.

[akpm@linux-foundation.org: simplify code]
Signed-off-by: NRaphael S. Carvalho <raphael.scarv@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Simplify the logic of variable assignments.

[akpm@linux-foundation.org: replace min_t with min, remove unneeded casts]
Signed-off-by: NZhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: NSimon Horman <horms@verge.net.au>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The types of the following local variables:

- ubytes/mbytes in kimage_load_crash_segment()/kimage_load_normal_segment()

- r in vmcoreinfo_append_str()

are wrong, so fix them.
Signed-off-by: NZhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Simon Horman <horms@verge.net.au>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are 2 well known and ancient problems with coredump/signals, and a
lot of related bug reports:

- do_coredump() clears TIF_SIGPENDING but of course this can't help
  if, say, SIGCHLD comes after that.

  In this case the coredump can fail unexpectedly. See for example
  wait_for_dump_helper()->signal_pending() check but there are other
  reasons.

- At the same time, dumping a huge core on the slow media can take a
  lot of time/resources and there is no way to kill the coredumping
  task reliably. In particular this is not oom_kill-friendly.

This patch tries to fix the 1st problem, and makes the preparation for the
next changes.

We add the new SIGNAL_GROUP_COREDUMP flag set by zap_threads() to indicate
that this process dumps the core.  prepare_signal() checks this flag and
nacks any signal except SIGKILL.

Note that this check tries to be conservative, in the long term we should
probably treat the SIGNAL_GROUP_EXIT case equally but this needs more
discussion.  See marc.info/?l=linux-kernel&m=120508897917439

Notes:
	- recalc_sigpending() doesn't check SIGNAL_GROUP_COREDUMP.
	  The patch assumes that dump_write/etc paths should never
	  call it, but we can change it as well.

	- There is another source of TIF_SIGPENDING, freezer. This
	  will be addressed separately.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Tested-by: NMandeep Singh Baines <msb@chromium.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This function suffers from not being able to determine if the cleanup is
called in case it returns -ENOMEM.  Nobody is using it anymore, so let's
remove it.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use call_usermodehelper_setup() + call_usermodehelper_exec() instead of
calling call_usermodehelper_fns().  In case the latter returns -ENOMEM the
cleanup function may had not been called - in this case we would not free
argv and module_name.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

call_usermodehelper_setup() + call_usermodehelper_exec() need to be
called instead of call_usermodehelper_fns() when the cleanup function
needs to be called even when an ENOMEM error occurs.  In this case using
call_usermodehelper_fns() the user can't distinguish if the cleanup
function was called or not.

[akpm@linux-foundation.org: export call_usermodehelper_setup() to modules]
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>
Reviewed-by: NOleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds a new ptrace request PTRACE_PEEKSIGINFO.

This request is used to retrieve information about pending signals
starting with the specified sequence number.  Siginfo_t structures are
copied from the child into the buffer starting at "data".

The argument "addr" is a pointer to struct ptrace_peeksiginfo_args.
struct ptrace_peeksiginfo_args {
	u64 off;	/* from which siginfo to start */
	u32 flags;
	s32 nr;		/* how may siginfos to take */
};

"nr" has type "s32", because ptrace() returns "long", which has 32 bits on
i386 and a negative values is used for errors.

Currently here is only one flag PTRACE_PEEKSIGINFO_SHARED for dumping
signals from process-wide queue.  If this flag is not set, signals are
read from a per-thread queue.

The request PTRACE_PEEKSIGINFO returns a number of dumped signals.  If a
signal with the specified sequence number doesn't exist, ptrace returns
zero.  The request returns an error, if no signal has been dumped.

Errors:
EINVAL - one or more specified flags are not supported or nr is negative
EFAULT - buf or addr is outside your accessible address space.

A result siginfo contains a kernel part of si_code which usually striped,
but it's required for queuing the same siginfo back during restore of
pending signals.

This functionality is required for checkpointing pending signals.  Pedro
Alves suggested using it in "gdb" to peek at pending signals.  gdb already
uses PTRACE_GETSIGINFO to get the siginfo for the signal which was already
dequeued.  This functionality allows gdb to look at the pending signals
which were not reported yet.

The prototype of this code was developed by Oleg Nesterov.
Signed-off-by: NAndrew Vagin <avagin@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pedro Alves <palves@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Andrew Morton noted:

	akpm3:/usr/src/25> grep SYSCALL kernel/timer.c
	SYSCALL_DEFINE1(alarm, unsigned int, seconds)
	SYSCALL_DEFINE0(getpid)
	SYSCALL_DEFINE0(getppid)
	SYSCALL_DEFINE0(getuid)
	SYSCALL_DEFINE0(geteuid)
	SYSCALL_DEFINE0(getgid)
	SYSCALL_DEFINE0(getegid)
	SYSCALL_DEFINE0(gettid)
	SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
	COMPAT_SYSCALL_DEFINE1(sysinfo, struct compat_sysinfo __user *, info)

	Only one of those should be in kernel/timer.c.  Who wrote this thing?

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The only use outside of kernel/timer.c was in kernel/compat.c, so move
compat_sys_sysinfo() next to sys_sysinfo() in kernel/timer.c.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We sometimes use "struct call_single_data *data" and sometimes "struct
call_single_data *csd".  Use "csd" consistently.

We sometimes use "struct call_function_data *data" and sometimes "struct
call_function_data *cfd".  Use "cfd" consistently.

Also, avoid some 80-col layout tricks.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The 'priv' field is redundant; we can pass data via 'info'.
Signed-off-by: Nliguang <lig.fnst@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>