linux.git/include/linux/sched.h, branch v2.6.26-rc2

Add new 'cond_resched_bkl()' helper function

2008-05-11T23:04:48+00:00

It acts exactly like a regular 'cond_resched()', but will not get
optimized away when CONFIG_PREEMPT is set.

Normal kernel code is already preemptable in the presense of
CONFIG_PREEMPT, so cond_resched() is optimized away (see commit
02b67cc3ba36bdba351d6c3a00593f4ec550d9d3 "sched: do not do
cond_resched() when CONFIG_PREEMPT").

But when wanting to conditionally reschedule while holding a lock, you
need to use "cond_sched_lock(lock)", and the new function is the BKL
equivalent of that.

Also make fs/locks.c use it.

Signed-off-by: Linus Torvalds

sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

2008-05-05T21:56:18+00:00

this replaces the rq->clock stuff (and possibly cpu_clock()).

 - architectures that have an 'imperfect' hardware clock can set
   CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

 - the 'jiffie' window might be superfulous when we update tick_gtod
   before the __update_sched_clock() call in sched_clock_tick()

 - cpu_clock() might be implemented as:

     sched_clock_cpu(smp_processor_id())

   if the accuracy proves good enough - how far can TSC drift in a
   single jiffie when considering the filtering and idle hooks?

[ mingo@elte.hu: various fixes and cleanups ]

Signed-off-by: Peter Zijlstra 
Signed-off-by: Ingo Molnar

sched: make clock sync tunable by architecture code

2008-05-05T21:56:18+00:00

make time_sync_thresh tunable to architecture code.

Signed-off-by: Ingo Molnar

sched: fix RT task-wakeup logic

2008-05-05T21:56:18+00:00

Dmitry Adamushko pointed out a logic error in task_wake_up_rt() where we
will always evaluate to "true".  You can find the thread here:

http://lkml.org/lkml/2008/4/22/296

In reality, we only want to try to push tasks away when a wake up request is
not going to preempt the current task.  So lets fix it.

Note: We introduce test_tsk_need_resched() instead of open-coding the flag
check so that the merge-conflict with -rt should help remind us that we
may need to support NEEDS_RESCHED_DELAYED in the future, too.

Signed-off-by: Gregory Haskins 
CC: Dmitry Adamushko 
CC: Steven Rostedt 
Signed-off-by: Ingo Molnar

Deprecate find_task_by_pid()

2008-04-30T15:29:48+00:00

There are some places that are known to operate on tasks'
global pids only:

* the rest_init() call (called on boot)
* the kgdb's getthread
* the create_kthread() (since the kthread is run in init ns)

So use the find_task_by_pid_ns(..., &init_pid_ns) there
and schedule the find_task_by_pid for removal.

[sukadev@us.ibm.com: Fix warning in kernel/pid.c]
Signed-off-by: Pavel Emelyanov 
Cc: "Eric W. Biederman" 
Signed-off-by: Sukadev Bhattiprolu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

signals: use HAVE_SET_RESTORE_SIGMASK

2008-04-30T15:29:37+00:00

Change all the #ifdef TIF_RESTORE_SIGMASK conditionals in non-arch code to
#ifdef HAVE_SET_RESTORE_SIGMASK.  If arch code defines it first, the generic
set_restore_sigmask() using TIF_RESTORE_SIGMASK is not defined.

Signed-off-by: Roland McGrath 
Cc: Oleg Nesterov 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: "Luck, Tony" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

signals: fix /sbin/init protection from unwanted signals

2008-04-30T15:29:37+00:00

The global init has a lot of long standing problems with the unhandled fatal
signals.

	- The "is_global_init(current)" check in get_signal_to_deliver()
	  protects only the main thread. Sub-thread can dequee the fatal
	  signal and shutdown the whole thread group except the main thread.
	  If it dequeues SIGSTOP /sbin/init will be stopped, this is not
	  right too. Note that we can't use is_global_init(->group_leader),
	  this breaks exec and this can't solve other problems we have.

	- Even if afterwards ignored, the fatal signals sets SIGNAL_GROUP_EXIT
	  on delivery. This breaks exec, has other bad implications, and this
	  is just wrong.

Introduce the new SIGNAL_UNKILLABLE flag to fix these problems.  It also helps
to solve some other problems addressed by the subsequent patches.

Currently we use this flag for the global init only, but it could also be used
by kthreads and (perhaps) by the sub-namespace inits.

Signed-off-by: Oleg Nesterov 
Acked-by: "Eric W. Biederman" 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

signals: join send_sigqueue() with send_group_sigqueue()

2008-04-30T15:29:36+00:00

We export send_sigqueue() and send_group_sigqueue() for the only user,
posix_timer_event().  This is a bit silly, because both are just trivial
helpers on top of do_send_sigqueue() and because the we pass the unused
.si_signo parameter.

Kill them both, rename do_send_sigqueue() to send_sigqueue(), and export it.

Signed-off-by: Oleg Nesterov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

signals: re-assign CLD_CONTINUED notification from the sender to reciever

2008-04-30T15:29:34+00:00

Based on discussion with Jiri and Roland.

In short: currently handle_stop_signal(SIGCONT, p) sends the notification to
p->parent, with this patch p itself notifies its parent when it becomes
running.

handle_stop_signal(SIGCONT) has to drop ->siglock temporary in order to notify
the parent with do_notify_parent_cldstop().  This leads to multiple problems:

	- as Jiri Kosina pointed out, the stopped task can resume without
	  actually seeing SIGCONT which may have a handler.

	- we race with another sig_kernel_stop() signal which may come in
	  that window.

	- we race with sig_fatal() signals which may set SIGNAL_GROUP_EXIT
	  in that window.

	- we can't avoid taking tasklist_lock() while sending SIGCONT.

With this patch handle_stop_signal() just sets the new SIGNAL_CLD_CONTINUED
flag in p->signal->flags and returns.  The notification is sent by the first
task which returns from finish_stop() (there should be at least one) or any
other signalled thread from get_signal_to_deliver().

This is a user-visible change.  Say, currently kill(SIGCONT, stopped_child)
can't return without seeing SIGCHLD, with this patch SIGCHLD can be delayed
unpredictably.  Another difference is that if the child is ptraced by another
process, CLD_CONTINUED may be delivered to ->real_parent after ptrace_detach()
while currently it always goes to the tracer which doesn't actually need this
notification.  Hopefully not a problem.

The patch asks for the futher obvious cleanups, I'll send them separately.

Signed-off-by: Oleg Nesterov 
Cc: Roland McGrath 
Cc: Jiri Kosina 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: add an owner to the mm_struct

2008-04-29T15:06:10+00:00

Remove the mem_cgroup member from mm_struct and instead adds an owner.

This approach was suggested by Paul Menage.  The advantage of this approach
is that, once the mm->owner is known, using the subsystem id, the cgroup
can be determined.  It also allows several control groups that are
virtually grouped by mm_struct, to exist independent of the memory
controller i.e., without adding mem_cgroup's for each controller, to
mm_struct.

A new config option CONFIG_MM_OWNER is added and the memory resource
controller selects this config option.

This patch also adds cgroup callbacks to notify subsystems when mm->owner
changes.  The mm_cgroup_changed callback is called with the task_lock() of
the new task held and is called just prior to changing the mm->owner.

I am indebted to Paul Menage for the several reviews of this patchset and
helping me make it lighter and simpler.

This patch was tested on a powerpc box, it was compiled with both the
MM_OWNER config turned on and off.

After the thread group leader exits, it's moved to init_css_state by
cgroup_exit(), thus all future charges from runnings threads would be
redirected to the init_css_set's subsystem.

Signed-off-by: Balbir Singh 
Cc: Pavel Emelianov 
Cc: Hugh Dickins 
Cc: Sudhir Kumar 
Cc: YAMAMOTO Takashi 
Cc: Hirokazu Takahashi 
Cc: David Rientjes ,
Cc: Balbir Singh 
Acked-by: KAMEZAWA Hiroyuki 
Acked-by: Pekka Enberg 
Reviewed-by: Paul Menage 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds