5030 Commits

Author SHA1 Message Date
Ingo Molnar
2c10c22af0 Merge branch 'linus' into sched/devel 2008-10-06 08:13:18 +02:00
Dario Faggioli
f6121f4f87 sched_rt.c: resch needed in rt_rq_enqueue() for the root rt_rq
While working on the new version of the code for SCHED_SPORADIC I
noticed something strange in the present throttling mechanism. More
specifically in the throttling timer handler in sched_rt.c
(do_sched_rt_period_timer()) and in rt_rq_enqueue().

The problem is that, when unthrottling a runqueue, rt_rq_enqueue() only
asks for rescheduling if the runqueue has a sched_entity associated to
it (i.e., rt_rq->rt_se != NULL).
Now, if the runqueue is the root rq (which has a rt_se = NULL)
rescheduling does not take place, and it is delayed to some undefined
instant in the future.

This imply some random bandwidth usage by the RT tasks under throttling.
For instance, setting rt_runtime_us/rt_period_us = 950ms/1000ms an RT
task will get less than 95%. In our tests we got something varying
between 70% to 95%.
Using smaller time values, e.g., 95ms/100ms, things are even worse, and
I can see values also going down to 20-25%!!

The tests we performed are simply running 'yes' as a SCHED_FIFO task,
and checking the CPU usage with top, but we can investigate thoroughly
if you think it is needed.

Things go much better, for us, with the attached patch... Don't know if
it is the best approach, but it solved the issue for us.

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-04 14:31:54 +02:00
Thomas Gleixner
07454bfff1 clockevents: check broadcast tick device not the clock events device
Impact: jiffies increment too fast.

Hugh Dickins noted that with NOHZ=n and HIGHRES=n jiffies get
incremented too fast. The reason is a wrong check in the broadcast
enter/exit code, which keeps the local apic timer in periodic mode
when the switch happens.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-04 10:51:07 +02:00
Frederic Weisbecker
d294eb83d8 cpusets: scan_for_empty_cpusets(), cpuset doesn't seem to be so const
This fixes a warning on latest -tip:

 kernel/cpuset.c: Dans la fonction «scan_for_empty_cpusets» :
 kernel/cpuset.c:1932: attention : passing argument 1 of «list_add_tail» discards qualifiers from pointer target type

Actually the struct cpuset *root passed in parameter to scan_for_empty_cpusets
is not supposed to be const since an entry is added on the tail of its list.
Just correct the qualifier.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-03 13:39:50 +02:00
Frederic Weisbecker
77af7e3403 softirq, warning fix: correct a format to avoid a warning
Last -tip gives this warning:

kernel/softirq.c: Dans la fonction «__do_softirq» :
kernel/softirq.c:216: attention : format «%ld» expects type «long int», but argument 2 has type «int»

This patch corrects the format type, and a small mistake in the "softirq" word.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-03 11:41:41 +02:00
Ingo Molnar
2ec2b482b1 rcu: RCU-based detection of stalled CPUs for Classic RCU, fix
fix the !CONFIG_RCU_CPU_STALL_DETECTOR path:

 kernel/rcuclassic.c: In function '__rcu_pending':
 kernel/rcuclassic.c:609: error: too few arguments to function 'check_cpu_stall'

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-03 10:41:00 +02:00
Paul E. McKenney
2133b5d7ff rcu: RCU-based detection of stalled CPUs for Classic RCU
This patch adds stalled-CPU detection to Classic RCU.  This capability
is enabled by a new config variable CONFIG_RCU_CPU_STALL_DETECTOR, which
defaults disabled.

This is a debugging feature to detect infinite loops in kernel code, not
something that non-kernel-hackers would be expected to care about.

This feature can detect looping CPUs in !PREEMPT builds and looping CPUs
with preemption disabled in PREEMPT builds.  This is essentially a port of
this functionality from the treercu patch, replacing the stall debug patch
that is already in tip/core/rcu (commit 67182ae1c4).

The changes from the patch in tip/core/rcu include making the config
variable name match that in treercu, changing from seconds to jiffies to
avoid spurious warnings, and printing a boot message when this feature
is enabled.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-03 10:36:08 +02:00
Ingo Molnar
b5259d9442 Merge commit 'v2.6.27-rc8' into core/rcu 2008-10-03 10:34:36 +02:00
Dan Carpenter
aa94fbd5cc fix error-path NULL deref in alloc_posix_timer()
Found by static checker (http://repo.or.cz/w/smatch.git).

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-02 15:53:13 -07:00
Thomas Gleixner
8e85b4b553 softirqs, debug: preemption check
if a preempt count leaks out of a softirq handler it can be very hard
to figure it out. Add a debug check for this.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-02 10:58:04 +02:00
David Brownell
0c5d1eb77a genirq: record trigger type
Genirq hasn't previously recorded the trigger type used by any given IRQ,
although some irq_chip support has done so.  That data can be useful when
troubleshooting.  This patch records it in the relevant irq_desc.status
bits, and improves consistency between the two driver-visible calls
affected:

 - Make set_irq_type() usage match request_irq() usage:
    * IRQ_TYPE_NONE should be a NOP; succeed, so irq_chip methods
      won't have to handle that case any more (many do it wrong).
    * IRQ_TYPE_PROBE is ignored; any buggy out-of-tree callers
      might need to switch over to the real IRQ probing code.
    * emit the same diagnostics (from shared utility code)

 - Their kerneldoc now reflects usage:
    * request_irq() flags include IRQF_TRIGGER_* to specify
      active edge(s)/level ... docs previously omitted that
    * set_irq_type() is declared in <linux/irq.h> so callers
      should use the (bit-equivalent) IRQ_TYPE_* symbols there

Also: adds a warning about shared IRQs that don't end up using the
requested trigger mode; and fix an unrelated "sparse" warning.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-02 10:24:09 +02:00
Ingo Molnar
d6d5aeb661 Merge commit 'v2.6.27-rc8' into genirq 2008-10-02 10:21:26 +02:00
Linus Torvalds
cf4b0b2c95 Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  hrtimer: prevent migration of per CPU hrtimers
  hrtimer: mark migration state
  hrtimer: fix migration of CB_IRQSAFE_NO_SOFTIRQ hrtimers
  hrtimer: migrate pending list on cpu offline

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2008-09-30 08:39:28 -07:00
Amit K. Arora
64b9e0294d sched: minor optimizations in wake_affine and select_task_rq_fair
This patch does following:
o Removes unused variable and argument "rq".
o Optimizes one of the "if" conditions in wake_affine() - i.e.  if
  "balanced" is true, we need not do rest of the calculations in the
  condition.
o If this cpu is same as the previous cpu (on which woken up task
  was running when it went to sleep), no need to call wake_affine at all.

Signed-off-by: Amit K Arora <aarora@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-30 15:25:44 +02:00
Ingo Molnar
1508487e7f timers: fix itimer/many thread hang, fix
fix bogus rq dereference: v3 removed the locking but also removed the rq
initialization.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-30 08:28:17 +02:00
Thomas Petazzoni
bfcd17a6c5 Configure out file locking features
This patch adds the CONFIG_FILE_LOCKING option which allows to remove
support for advisory locks. With this patch enabled, the flock()
system call, the F_GETLK, F_SETLK and F_SETLKW operations of fcntl()
and NFS support are disabled. These features are not necessarly needed
on embedded systems. It allows to save ~11 Kb of kernel code and data:

   text          data     bss     dec     hex filename
1125436        118764  212992 1457192  163c28 vmlinux.old
1114299        118564  212992 1445855  160fdf vmlinux
 -11137    -200       0  -11337   -2C49 +/-

This patch has originally been written by Matt Mackall
<mpm@selenic.com>, and is part of the Linux Tiny project.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: matthew@wil.cx
Cc: linux-fsdevel@vger.kernel.org
Cc: mpm@selenic.com
Cc: akpm@linux-foundation.org
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
2008-09-29 17:56:57 -04:00
Balbir Singh
31a78f23ba mm owner: fix race between swapoff and exit
There's a race between mm->owner assignment and swapoff, more easily
seen when task slab poisoning is turned on.  The condition occurs when
try_to_unuse() runs in parallel with an exiting task.  A similar race
can occur with callers of get_task_mm(), such as /proc/<pid>/<mmstats>
or ptrace or page migration.

CPU0                                    CPU1
                                        try_to_unuse
                                        looks at mm = task0->mm
                                        increments mm->mm_users
task 0 exits
mm->owner needs to be updated, but no
new owner is found (mm_users > 1, but
no other task has task->mm = task0->mm)
mm_update_next_owner() leaves
                                        mmput(mm) decrements mm->mm_users
task0 freed
                                        dereferencing mm->owner fails

The fix is to notify the subsystem via mm_owner_changed callback(),
if no new owner is found, by specifying the new task as NULL.

Jiri Slaby:
mm->owner was set to NULL prior to calling cgroup_mm_owner_callbacks(), but
must be set after that, so as not to pass NULL as old owner causing oops.

Daisuke Nishimura:
mm_update_next_owner() may set mm->owner to NULL, but mem_cgroup_from_task()
and its callers need to take account of this situation to avoid oops.

Hugh Dickins:
Lockdep warning and hang below exec_mmap() when testing these patches.
exit_mm() up_reads mmap_sem before calling mm_update_next_owner(),
so exec_mmap() now needs to do the same.  And with that repositioning,
there's now no point in mm_need_new_owner() allowing for NULL mm.

Reported-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-09-29 08:41:47 -07:00
Thomas Gleixner
ccc7dadf73 hrtimer: prevent migration of per CPU hrtimers
Impact: per CPU hrtimers can be migrated from a dead CPU

The hrtimer code has no knowledge about per CPU timers, but we need to
prevent the migration of such timers and warn when such a timer is
active at migration time.

Explicitely mark the timers as per CPU and use a more understandable
mode descriptor for the interrupts safe unlocked callback mode, which
is used by hrtimer_sleeper and the scheduler code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-29 17:09:14 +02:00
Thomas Gleixner
b00c1a99e7 hrtimer: mark migration state
Impact: during migration active hrtimers can be seen as inactive

The migration code removes the hrtimers from the queues of the dead
CPU and sets the state temporary to INACTIVE. The enqueue code sets it
to ACTIVE/PENDING again.

Prevent that the wrong state can be seen by using a separate migration
state bit.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-29 17:09:14 +02:00
Thomas Gleixner
41e1022eae hrtimer: fix migration of CB_IRQSAFE_NO_SOFTIRQ hrtimers
Impact: Stale timers after a CPU went offline.

commit 37bb6cb4097e29ffee970065b74499cbf10603a3
       hrtimer: unlock hrtimer_wakeup

changed the hrtimer sleeper callback mode to CB_IRQSAFE_NO_SOFTIRQ due
to locking problems. A result of this change is that when enqueue is
called for an already expired hrtimer the callback function is not
longer called directly from the enqueue code. The normal callers have
been fixed in the code, but the migration code which moves hrtimers
from a dead CPU to a live CPU was not made aware of this.

This can be fixed by checking the timer state after the call to
enqueue in the migration code.


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-29 17:09:14 +02:00
Thomas Gleixner
7659e34967 hrtimer: migrate pending list on cpu offline
Impact: hrtimers which are on the pending list are not migrated at cpu
	offline and can be stale forever

Add the pending list migration when CONFIG_HIGH_RES_TIMERS is enabled

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-29 17:09:13 +02:00
Frank Mayhar
7086efe1c1 timers: fix itimer/many thread hang, v3
- fix UP lockup
- another set of UP/SMP cleanups and simplifications

Signed-off-by: Frank Mayhar <fmayhar@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-27 20:04:45 +02:00
Jason Wessel
d7161a6534 kgdb, x86, arm, mips, powerpc: ignore user space single stepping
On the x86 arch, user space single step exceptions should be ignored
if they occur in the kernel space, such as ptrace stepping through a
system call.

First check if it is kgdb that is executing a single step, then ensure
it is not an accidental traversal into the user space, while in kgdb,
any other time the TIF_SINGLESTEP is set, kgdb should ignore the
exception.

On x86, arm, mips and powerpc, the kgdb_contthread usage was
inconsistent with the way single stepping is implemented in the kgdb
core.  The arch specific stub should always set the
kgdb_cpu_doing_single_step correctly if it is single stepping.  This
allows kgdb to correctly process an instruction steps if ptrace
happens to be requesting an instruction step over a system call.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2008-09-26 10:36:41 -05:00
Atsuo Igarashi
18d6522b86 kgdb: could not write to the last of valid memory with kgdb
On the ARM architecture, kgdb will crash the kernel if the last byte
of valid memory is written due to a flush_icache_range flushing
beyond the memory boundary.

Signed-off-by: Atsuo Igarashi <atsuo_igarashi@tripeaks.co.jp>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2008-09-26 10:36:41 -05:00
Ingo Molnar
13eb83754b IO resources, x86: ioremap sanity check to catch mapping requests exceeding, fix
fix this build error:

 kernel/resource.c: In function 'iomem_map_sanity_check':
 kernel/resource.c:842: error: implicit declaration of function 'r_next'
 kernel/resource.c:842: warning: assignment makes pointer from integer without a cast

r_next() was only available if CONFIG_PROCFS was enabled.

and fix this build warning:

 kernel/resource.c:855: warning: format '%llx' expects type 'long long unsigned int', but argument 2 has type 'resource_size_t'
 kernel/resource.c:855: warning: format '%llx' expects type 'long long unsigned int', but argument 3 has type 'long unsigned int'
 kernel/resource.c:855: warning: format '%llx' expects type 'long long unsigned int', but argument 4 has type 'resource_size_t'
 kernel/resource.c:855: warning: format '%llx' expects type 'long long unsigned int', but argument 5 has type 'resource_size_t'

resource_t can be 32 bits.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-26 10:10:12 +02:00
Suresh Siddha
379daf6290 IO resources, x86: ioremap sanity check to catch mapping requests exceeding the BAR sizes
Go through the iomem resource tree to check if any of the ioremap()
requests span more than any slot in the iomem resource tree and do
a WARN_ON() if we hit this check.

This will raise a red-flag, if some driver is mapping more than what
is needed. And hopefully identify possible corruptions much earlier.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-26 09:42:20 +02:00
Bharata B Rao
b87f17242d sched: maintain only task entities in cfs_rq->tasks list
cfs_rq->tasks list is used by the load balancer to iterate
over all the tasks. Currently it holds all the entities
(both task and group entities) because of which there is
a need to check for group entities explicitly during load
balancing. This patch changes the cfs_rq->tasks list to
hold only task entities.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-25 11:24:11 +02:00
Roman Zippel
d40e944c25 ntp: improve adjtimex frequency rounding
Change PPM_SCALE_INV_SHIFT so that it doesn't throw away any input bits
(19 is the amount of the factor 2 in PPM_SCALE), the output frequency
can then be calculated back to its input value, as the inverse divide
produce a slightly larger value, which is then correctly rounded by the
final shift.

Reported-by: Martin Ziegler <ziegler@uni-freiburg.de>
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 17:33:13 +02:00
Roman Zippel
5cd1c9c5cf timekeeping: fix rounding problem during clock update
Due to a rounding problem during a clock update it's possible for readers
to observe the clock jumping back by 1nsec.  The following simplified
example demonstrates the problem:

cycle	xtime
0	0
1000	999999.6
2000	1999999.2
3000	2999998.8
...

1500 =	1499999.4
=	0.0 + 1499999.4
=	999999.6 + 499999.8

When reading the clock only the full nanosecond part is used, while
timekeeping internally keeps nanosecond fractions.  If the clock is now
updated at cycle 1500 here, a nanosecond is missing due to the truncation.

The simple fix is to round up the xtime value during the update, this also
changes the distance to the reference time, but the adjustment will
automatically take care that it stays under control.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 17:33:13 +02:00
Maciej W. Rozycki
eb3f938fd6 ntp: let update_persistent_clock() sleep
This is a change that makes the 11-minute RTC update be run in the process
context.  This is so that update_persistent_clock() can sleep, which may
be required for certain types of RTC hardware -- most notably I2C devices.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Brownell <david-b@pacbell.net>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 17:33:12 +02:00
Oleg Nesterov
31d9284569 posix-timers: lock_timer: make it readable
Cleanup.  Imho makes the code much more understandable.  At least this
patch lessens both the source and compiled code.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:48 +02:00
Oleg Nesterov
5a51b713cc posix-timers: lock_timer: kill the bogus ->it_id check
lock_timer() checks that the timer found by idr_find(timer_id) has ->it_id
== timer_id.  This buys nothing.  This check can fail only if
sys_timer_create() unlocked idr_lock after idr_get_new(), but didn't set
->it_id = new_timer_id yet.  But in that case ->it_process == NULL so
lock_timer() can't succeed anyway.

Also remove a couple of unneeded typecasts.

Note that with or without this patch we have a small problem. 
sys_timer_create() doesn't ensure that the result of setting (say)
->it_sigev_notify must be visible if lock_timer() succeeds.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:48 +02:00
Oleg Nesterov
5a9fa73072 posix-timers: kill ->it_sigev_signo and ->it_sigev_value
With the recent changes ->it_sigev_signo and ->it_sigev_value are only
used in sys_timer_create(), kill them.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:48 +02:00
Oleg Nesterov
ef864c9588 posix-timers: sys_timer_create: cleanup the error handling
Cleanup.

- sys_timer_create() is big and complicated. The code above the "out:"
  label relies on the fact that "error" must be == 0. This is not very
  robust, make the code more explicit. Remove the unneeded initialization
  of error.

- If idr_get_new() succeeds (as it normally should), we check the returned
  value twice. Move the "-EAGAIN" check under "if (error)".

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:48 +02:00
Oleg Nesterov
717835d94d posix-timers: move the initialization of timer->sigq from send to create path
posix_timer_event() always populates timer->sigq with the same numbers,
move this code into sys_timer_create().

Note that with this patch we can kill it_sigev_signo and it_sigev_value.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:48 +02:00
Oleg Nesterov
36b2f04600 posix-timers: sys_timer_create: simplify and s/tasklist/rcu/
- Change the code to do rcu_read_lock() instead of taking tasklist_lock,
  it is safe to get_task_struct(p) if p was found under RCU.

  However, now we must not use process's sighand/signal, they may be NULL.
  We can use current->sighand/signal instead, this "process" must belong
  to the current's thread-group.

- Factor out the common code for 2 "if (timer_event_spec)" branches, the
  !timer_event_spec case can use current too.

- use spin_lock_irq() instead of _irqsave(), kill "flags".

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:48 +02:00
Oleg Nesterov
2cd499e38e posix-timers: sys_timer_create: remove the buggy PF_EXITING check
sys_timer_create() return -EINVAL if the target thread has PF_EXITING.

This doesn't really make sense, the sub-thread can die right after unlock.
And in fact, this is just wrong.  Without SIGEV_THREAD_ID good_sigevent()
returns ->group_leader, and it is very possible that the leader is already
dead.  This is OK, we shouldn't return the error in this case.

Remove this check and the comment.  Note that the "process" was found
under tasklist_lock, it must have ->sighand != NULL.

Also, remove a couple of unneeded initializations.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:47 +02:00
Oleg Nesterov
918fc03728 posix-timers: always do get_task_struct(timer->it_process)
Change the code to get/put timer->it_process regardless of
SIGEV_THREAD_ID.  This streamlines the create/destroy paths and allows us
to simplify the usage of exit_itimers() in de_thread().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:47 +02:00
Oleg Nesterov
4aa7361179 posix-timers: don't switch to ->group_leader if ->it_process dies
posix_timer_event() drops SIGEV_THREAD_ID and switches to ->group_leader
if send_sigqueue() fails.

This is not very useful and doesn't work reliably.  send_sigqueue() can
only fail if ->it_process is dead.  But it can die before it dequeues the
SI_TIMER signal, in that case the timer stops anyway.

Remove this code.  I guess it was needed a long ago to ensure that the
timer is not destroyed when when its creator thread dies.

Q: perhaps it makes sense to change sys_timer_settime() to return an error
if ->it_process is dead?

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-24 15:45:47 +02:00
Linus Torvalds
8553f321e0 Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  timers: fix build error in !oneshot case
  x86: c1e_idle: don't mark TSC unstable if CPU has invariant TSC
  x86: prevent C-states hang on AMD C1E enabled machines
  clockevents: prevent mode mismatch on cpu online
  clockevents: check broadcast device not tick device
  clockevents: prevent stale tick_next_period for onlining CPUs
  x86: prevent stale state of c1e_mask across CPU offline/online
  clockevents: prevent cpu online to interfere with nohz
2008-09-23 14:57:36 -07:00
Linus Torvalds
be3be89058 Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: fix init_hrtick() section mismatch warning
2008-09-23 14:57:22 -07:00
Jonathan Steel
f9092f358b kexec: fix segmentation fault in kimage_add_entry
A segmentation fault can occur in kimage_add_entry in kexec.c when loading
a kernel image into memory.  The fault occurs because a page is requested
by calling kimage_alloc_page with gfp_mask GFP_KERNEL and the function may
actually return a page with gfp_mask GFP_HIGHUSER.  The high mem page is
returned because it was swapped with the kernel page due to the kernel
page being a page that will shortly be copied to.

This patch ensures that kimage_alloc_page returns a page that was created
with the correct gfp flags.

I have verified the change and fixed the whitespace damage of the original
patch.  Jonathan did a great job of tracking this down after he hit the
problem.  -- Eric

Signed-off-by: Jonathan Steel <jon.steel@esentire.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-09-23 08:09:14 -07:00
Peter Zijlstra
57fdc26d4a sched: fixup buddy selection
We should set the buddy even though we might already have the
TIF_RESCHED flag set.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-23 16:23:17 +02:00
Peter Zijlstra
4653f803e6 sched: more sanity checks on the bandwidth settings
While playing around with it, I noticed we missed some sanity checks.
Also add some comments while we're there.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-23 16:23:16 +02:00
Peter Zijlstra
78333cdd0e sched: add some comments to the bandwidth code
Hopefully clarify some of this code a little.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-23 16:23:16 +02:00
Peter Zijlstra
940959e939 sched: fixlet for group load balance
We should not only correct the increment for the initial group, but should
be consistent and do so for all the groups we encounter.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-23 16:23:15 +02:00
Ingo Molnar
63e5c39859 Merge branches 'sched/urgent' and 'sched/rt' into sched/devel 2008-09-23 16:23:05 +02:00
Peter Zijlstra
6956985009 sched: rework wakeup preemption
Rework the wakeup preemption to work on real runtime instead of
the virtual runtime. This greatly simplifies the code.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-23 14:54:23 +02:00
Frank Mayhar
bb34d92f64 timers: fix itimer/many thread hang, v2
This is the second resubmission of the posix timer rework patch, posted
a few days ago.

This includes the changes from the previous resubmittion, which addressed
Oleg Nesterov's comments, removing the RCU stuff from the patch and
un-inlining the thread_group_cputime() function for SMP.

In addition, per Ingo Molnar it simplifies the UP code, consolidating much
of it with the SMP version and depending on lower-level SMP/UP handling to
take care of the differences.

It also cleans up some UP compile errors, moves the scheduler stats-related
macros into kernel/sched_stats.h, cleans up a merge error in
kernel/fork.c and has a few other minor fixes and cleanups as suggested
by Oleg and Ingo. Thanks for the review, guys.

Signed-off-by: Frank Mayhar <fmayhar@google.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-23 13:38:44 +02:00
Ingo Molnar
f8e256c687 timers: fix build error in !oneshot case
kernel/time/tick-common.c: In function ‘tick_setup_periodic’:
 kernel/time/tick-common.c:113: error: implicit declaration of function ‘tick_broadcast_oneshot_active’

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-23 12:57:00 +02:00