Impact: fix incorrect locking triggered during hotplug-intense stress-tests

While migrating the the CB_IRQSAFE_UNLOCKED timers during a cpu-offline,
we queue them on the cb_pending list, so that they won't go
stale.

Thus, when the callbacks of the timers run from the softirq context,
they could run into potential deadlocks, since these callbacks
assume that they're running with irq's disabled, thereby annoying
lockdep!

Fix this by emulating hardirq context while running these callbacks from
the hrtimer softirq.

=================================
[ INFO: inconsistent lock state ]
2.6.27 #2
--------------------------------
inconsistent {in-hardirq-W} -> {hardirq-on-W} usage.
ksoftirqd/0/4 [HC0[0]:SC1[1]:HE1:SE0] takes:
 (&rq->lock){++..}, at: [<c011db84>] sched_rt_period_timer+0x9e/0x1fc
{in-hardirq-W} state was registered at:
  [<c014103c>] __lock_acquire+0x549/0x121e
  [<c0107890>] native_sched_clock+0x88/0x99
  [<c013aa12>] clocksource_get_next+0x39/0x3f
  [<c0139abc>] update_wall_time+0x616/0x7df
  [<c0141d6b>] lock_acquire+0x5a/0x74
  [<c0121724>] scheduler_tick+0x3a/0x18d
  [<c047ed45>] _spin_lock+0x1c/0x45
  [<c0121724>] scheduler_tick+0x3a/0x18d
  [<c0121724>] scheduler_tick+0x3a/0x18d
  [<c012c436>] update_process_times+0x3a/0x44
  [<c013c044>] tick_periodic+0x63/0x6d
  [<c013c062>] tick_handle_periodic+0x14/0x5e
  [<c010568c>] timer_interrupt+0x44/0x4a
  [<c0150c9f>] handle_IRQ_event+0x13/0x3d
  [<c0151c14>] handle_level_irq+0x79/0xbd
  [<c0105634>] do_IRQ+0x69/0x7d
  [<c01041e4>] common_interrupt+0x28/0x30
  [<c047007b>] aac_probe_one+0x1a3/0x3f3
  [<c047ec2d>] _spin_unlock_irqrestore+0x36/0x39
  [<c01512b4>] setup_irq+0x1be/0x1f9
  [<c065d70b>] start_kernel+0x259/0x2c5
  [<ffffffff>] 0xffffffff
irq event stamp: 50102
hardirqs last  enabled at (50102): [<c047ebf4>] _spin_unlock_irq+0x20/0x23
hardirqs last disabled at (50101): [<c047edc2>] _spin_lock_irq+0xa/0x4b
softirqs last  enabled at (50088): [<c0128ba6>] do_softirq+0x37/0x4d
softirqs last disabled at (50099): [<c0128ba6>] do_softirq+0x37/0x4d

other info that might help us debug this:
no locks held by ksoftirqd/0/4.

stack backtrace:
Pid: 4, comm: ksoftirqd/0 Not tainted 2.6.27 #2
 [<c013f6cb>] print_usage_bug+0x13e/0x147
 [<c013fef5>] mark_lock+0x493/0x797
 [<c01410b1>] __lock_acquire+0x5be/0x121e
 [<c0141d6b>] lock_acquire+0x5a/0x74
 [<c011db84>] sched_rt_period_timer+0x9e/0x1fc
 [<c047ed45>] _spin_lock+0x1c/0x45
 [<c011db84>] sched_rt_period_timer+0x9e/0x1fc
 [<c011db84>] sched_rt_period_timer+0x9e/0x1fc
 [<c01210fd>] finish_task_switch+0x41/0xbd
 [<c0107890>] native_sched_clock+0x88/0x99
 [<c011dae6>] sched_rt_period_timer+0x0/0x1fc
 [<c0136dda>] run_hrtimer_pending+0x54/0xe5
 [<c011dae6>] sched_rt_period_timer+0x0/0x1fc
 [<c0128afb>] __do_softirq+0x7b/0xef
 [<c0128ba6>] do_softirq+0x37/0x4d
 [<c0128c12>] ksoftirqd+0x56/0xc5
 [<c0128bbc>] ksoftirqd+0x0/0xc5
 [<c0134649>] kthread+0x38/0x5d
 [<c0134611>] kthread+0x0/0x5d
 [<c0104477>] kernel_thread_helper+0x7/0x10
 =======================
Signed-off-by: NGautham R Shenoy <ego@in.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: N"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: nohz powersavings and wakeup regression

commit fb02fbc1 (NOHZ: restart tick
device from irq_enter()) causes a serious wakeup regression.

While the patch is correct it does not take into account that spurious
wakeups happen on x86. A fix for this issue is available, but we just
revert to the .27 behaviour and let long running softirqs screw
themself.

Disable it for now.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Impact: avoid spurious ksoftirqd wakeups

The tick idle check which is called from irq_enter() was run before
the call to __irq_enter() which did not set the in_interrupt() bits in
preempt_count. That way the raise of a softirq woke up softirqd for
nothing as the softirq was handled on return from interrupt.

Call __irq_enter() before calling into the tick idle check code.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Some functions that may be called from this handler require that
interrupts are disabled. Also, combining IRQF_DISABLED and
IRQF_SHARED does not reliably disable interrupts in a handler, so
remove IRQF_SHARED from the irq flags (this irq is not shared anyway).
Signed-off-by: NMatt Fleming <mjf@gentoo.org>
Cc: mingo@elte.hu
Cc: venkatesh.pallipadi@intel.com
Cc: "Will Newton" <will.newton@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

In hpet_next_event() we check that the value we just wrote to
HPET_Tn_CMP(timer) has reached the chip. Currently, we're checking that
the value we wrote to HPET_Tn_CMP(timer) is in HPET_T0_CMP, which, if
timer is anything other than timer 0, is likely to fail.
Signed-off-by: NMatt Fleming <mjf@gentoo.org>
Cc: mingo@elte.hu
Cc: venkatesh.pallipadi@intel.com
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

It is possible to flood the console with call traces if the WARN_ON
condition is true because of the frequency with which this function is
called.
Signed-off-by: NMatt Fleming <mjf@gentoo.org>
Cc: mingo@elte.hu
Cc: venkatesh.pallipadi@intel.com
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

It's showing up as regressions; disabling it very likely just papers
over an underlying issue, but time is running out for 2.6.28, lets get
back to this for 2.6.29

Fixes: #11826 and #11893
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-fixes:
  kbuild: Fixup deb-pkg target to generate separate firmware deb

The below is a simplistic fix for "make deb-pkg"; it splits the
firmware out to a linux-firmware-image package and adds an
(unversioned) Suggests to the linux package for this firmware.
Signed-Off-By: NJonathan McDowell <noodles@earth.li>
Acked-by: NFrans Pop <elendil@planet.nl>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

The "Exclude staging drivers" question is there so that we don't build
staging drivers for allyesconfig or allnoconfig settings, but it's very
irritating when you've already said "no" to staging drivers earlier.

There is absolutely no point in declining twice - once you've declined
the staging drivers, you're done.

So make the second question depend on the first question having been
answered in the affirmative.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'for-2.6.28' of git://linux-nfs.org/~bfields/linux:
  Fix nfsd truncation of readdir results

* 'cpus4096' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  cpumask: introduce new API, without changing anything, v3
  cpumask: new API, v2
  cpumask: introduce new API, without changing anything

Commit 8d7c4203 "nfsd: fix failure to set eof in readdir in some
situations" introduced a bug: on a directory in an exported ext3
filesystem with dir_index unset, a READDIR will only return about 250
entries, even if the directory was larger.

Bisected it back to this commit; reverting it fixes the problem.

It turns out that in this case ext3 reads a block at a time, then
returns from readdir, which means we can end up with buf.full==0 but
with more entries in the directory still to be read.  Before 8d7c4203
(but after c002a6c7 "Optimise NFS readdir hack slightly"), this would
cause us to return the READDIR result immediately, but with the eof bit
unset.  That could cause a performance regression (because the client
would need more roundtrips to the server to read the whole directory),
but no loss in correctness, since the cleared eof bit caused the client
to send another readdir.  After 8d7c4203, the setting of the eof bit
made this a correctness problem.

So, move nfserr_eof into the loop and remove the buf.full check so that
we loop until buf.used==0.  The following seems to do the right thing
and reduces the network traffic since we don't return a READDIR result
until the buffer is full.

Tested on an empty directory & large directory; eof is properly sent and
there are no more short buffers.
Signed-off-by: NDoug Nazar <nazard@dragoninc.ca>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>

Impact: cleanup

Clean up based on feedback from Andrew Morton and others:

 - change to inline functions instead of macros
 - add __init to bootmem method
 - add a missing debug check
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Previously I assumed that the receive queues of candidates don't
change during the GC.  This is only half true, nothing can be received
from the queues (see comment in unix_gc()), but buffers could be added
through the other half of the socket pair, which may still have file
descriptors referring to it.

This can result in inc_inflight_move_tail() erronously increasing the
"inflight" counter for a unix socket for which dec_inflight() wasn't
previously called.  This in turn can trigger the "BUG_ON(total_refs <
inflight_refs)" in a later garbage collection run.

Fix this by only manipulating the "inflight" counter for sockets which
are candidates themselves.  Duplicating the file references in
unix_attach_fds() is also needed to prevent a socket becoming a
candidate for GC while the skb that contains it is not yet queued.
Reported-by: NAndrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, all existing users of cnt32_to_63() are fine since the CPU
architectures where it is used don't do read access reordering, and user
mode preemption is disabled already.  It is nevertheless a good idea to
better elaborate usage requirements wrt preemption, and use an explicit
memory barrier on SMP to avoid different CPUs accessing the counter
value in the wrong order.  On UP a simple compiler barrier is
sufficient.
Signed-off-by: NNicolas Pitre <nico@marvell.com>
Acked-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/drzeus/mmc:
  mmc: struct device - replace bus_id with dev_name(), dev_set_name()
  mmc: increase SD write timeout for crappy cards

Use menuconfig instead of flat configs so that you can disable/enable
regulator items with one selection.  Also, use depends instead of
reverse selections to make life easier, too.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NLiam Girdwood <lrg@slimlogic.co.uk>

Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-Off-By: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NPierre Ossman <drzeus@drzeus.cx>

It seems that some cards are slightly out of spec and occasionally
will not be able to complete a write in the alloted 250 ms [1].
Incease the timeout slightly to allow even these cards to function
properly.

[1] http://lkml.org/lkml/2008/9/23/390Signed-off-by: NPierre Ossman <drzeus@drzeus.cx>

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: optimize sched_clock() a bit
  sched: improve sched_clock() performance

Merge branch 'oprofile-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'oprofile-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  oprofile: Fix p6 counter overflow check
  Cell OProfile: Incorrect local array size in activate spu profiling function
  Revert "Cell OProfile: Incorrect local array size in activate spu profiling function"
  oprofile: fix memory ordering
  Cell OProfile: Incorrect local array size in activate spu profiling function
  Change UTF8 chars in Kconfig help text about Oprofile AMD barcelona

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6:
  Staging: make usbip depend on CONFIG_NET
  Staging: only build the tree if we really want to

Fix the __pfn_to_page(pfn) macro so that it doesn't evaluate its
argument twice in the CONFIG_DISCONTIGMEM=y case, because 'pfn' may
be a result of a funtion call having side effects.

For example, the hibernation code applies pfn_to_page(pfn) to the
result of a function returning the pfn corresponding to the next set
bit in a bitmap and the current bit position is modified on each
call.  This leads to "interesting" failures for CONFIG_DISCONTIGMEM=y
due to the current behavior of __pfn_to_page(pfn).
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

sched_clock() uses cycles_2_ns() needlessly - which is an irq-disabling
variant of __cycles_2_ns().

Most of the time sched_clock() is called with irqs disabled already.
The few places that call it with irqs enabled need to be updated.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

in scheduler-intense workloads native_read_tsc() overhead accounts for
20% of the system overhead:

 659567 system_call                              41222.9375
 686796 schedule                                 435.7843
 718382 __switch_to                              665.1685
 823875 switch_mm                                4526.7857
 1883122 native_read_tsc                          55385.9412
 9761990 total                                      2.8468

this is large part due to the rdtsc_barrier() that is done before
and after reading the TSC.

But sched_clock() is not a precise clock in the GTOD sense, using such
barriers is completely pointless. So remove the barriers and only use
them in vget_cycles().

This improves lat_ctx performance by about 5%.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Thanks to Randy Dunlap for finding this problem.
Reported-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This Kconfig change allows the common 'make allmodconfig' and
'make allyesconfig' build options to skip the staging tree, which is
probably what you want to have happen anyway.

This makes the linux-next developer's life a lot easier so he doesn't
have to worry about changes that break the staging tree, that's for me
to worry about...
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Merge branch 'oprofile-for-tip' of git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile into x86/urgent

* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6:
  [IA64] Reserve elfcorehdr memory in CONFIG_CRASH_DUMP
  [IA64] fix boot panic caused by offline CPUs
  [IA64] reorder Kconfig options to match x86
  [IA64] Build VT-D iommu support into generic kernel
  [IA64] remove dead BIO_VMERGE_BOUNDARY definition
  [IA64] remove duplicated #include from pci-dma.c
  [IA64] use common header for software IO/TLB
  [IA64] fix the difference between node_mem_map and node_start_pfn
  [IA64] Add error_recovery_info field to SAL section header
  [IA64] Add UV watchlist support.
  [IA64] Simplify SGI uv vs. sn2 driver issues

IA64 kdump kernel failed to initialize /proc/vmcore in 2.6.28-rc2.
A bug was introduced in this patch commit:

  d9a9855d
  always reserve elfcore header memory in crash kernel

The problem was that the call to reserve_elfcorehdr() should be placed
in CONFIG_CRASH_DUMP rather than in CONFIG_CRASH_KERNEL, which does
not exist.
Signed-off-by: NJay Lan <jlan@sgi.com>
Acked-by: NSimon Hormon <horms@verge.net.au>
Signed-off-by: NTony Luck <tony.luck@intel.com>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
  PCI: fix range check on mmapped sysfs resource files
  PCI: remove excess kernel-doc notation
  PCI: annotate return value of pci_ioremap_bar with __iomem
  PCI: fix VPD limit quirk for Broadcom 5708S

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, xen: fix use of pgd_page now that it really does return a page

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: fine-tune SD_SIBLING_INIT
  sched: fine-tune SD_MC_INIT
  sched: fix memory leak in a failure path
  sched: fix a bug in sched domain degenerate

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  xen: make sure stray alias mappings are gone before pinning
  vmap: cope with vm_unmap_aliases before vmalloc_init()

Fix the counter overflow check for CPUs with counter width > 32

I had a similar change in a different patch that I didn't submit
and I didn't notice the problem earlier because it was always
tested together.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NRobert Richter <robert.richter@amd.com>

This triggers false bug reports as it does a bogus kmalloc with locks held
but is never really compiled into the kernel.

Closes #8329
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

As we've lost our trivial maintainer for the moment I'll send this
directly. Only touches a comment
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: add checksum calculation when clearing UNINIT flag in ext4_new_inode
  ext4: Mark the buffer_heads as dirty and uptodate after prepare_write
  ext4: calculate journal credits correctly
  ext4: wait on all pending commits in ext4_sync_fs()
  ext4: Convert to host order before using the values.
  ext4: fix missing ext4_unlock_group in error path
  jbd2: deregister proc on failure in jbd2_journal_init_inode
  jbd2: don't give up looking for space so easily in __jbd2_log_wait_for_space
  jbd: don't give up looking for space so easily in __log_wait_for_space