Commit graph

15731 commits

Author SHA1 Message Date
Linus Torvalds
f076ab8d04 Merge branch 'kvm-updates-2.6.27' of git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm
* 'kvm-updates-2.6.27' of git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm: (70 commits)
  KVM: Adjust smp_call_function_mask() callers to new requirements
  KVM: MMU: Fix potential race setting upper shadow ptes on nonpae hosts
  KVM: x86 emulator: emulate clflush
  KVM: MMU: improve invalid shadow root page handling
  KVM: MMU: nuke shadowed pgtable pages and ptes on memslot destruction
  KVM: Prefix some x86 low level function with kvm_, to avoid namespace issues
  KVM: check injected pic irq within valid pic irqs
  KVM: x86 emulator: Fix HLT instruction
  KVM: Apply the kernel sigmask to vcpus blocked due to being uninitialized
  KVM: VMX: Add ept_sync_context in flush_tlb
  KVM: mmu_shrink: kvm_mmu_zap_page requires slots_lock to be held
  x86: KVM guest: make kvm_smp_prepare_boot_cpu() static
  KVM: SVM: fix suspend/resume support
  KVM: s390: rename private structures
  KVM: s390: Set guest storage limit and offset to sane values
  KVM: Fix memory leak on guest exit
  KVM: s390: dont allocate dirty bitmap
  KVM: move slots_lock acquision down to vapic_exit
  KVM: VMX: Fake emulate Intel perfctr MSRs
  KVM: VMX: Fix a wrong usage of vmcs_config
  ...
2008-07-20 21:13:26 -07:00
Linus Torvalds
db6d8c7a40 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (1232 commits)
  iucv: Fix bad merging.
  net_sched: Add size table for qdiscs
  net_sched: Add accessor function for packet length for qdiscs
  net_sched: Add qdisc_enqueue wrapper
  highmem: Export totalhigh_pages.
  ipv6 mcast: Omit redundant address family checks in ip6_mc_source().
  net: Use standard structures for generic socket address structures.
  ipv6 netns: Make several "global" sysctl variables namespace aware.
  netns: Use net_eq() to compare net-namespaces for optimization.
  ipv6: remove unused macros from net/ipv6.h
  ipv6: remove unused parameter from ip6_ra_control
  tcp: fix kernel panic with listening_get_next
  tcp: Remove redundant checks when setting eff_sacks
  tcp: options clean up
  tcp: Fix MD5 signatures for non-linear skbs
  sctp: Update sctp global memory limit allocations.
  sctp: remove unnecessary byteshifting, calculate directly in big-endian
  sctp: Allow only 1 listening socket with SO_REUSEADDR
  sctp: Do not leak memory on multiple listen() calls
  sctp: Support ipv6only AF_INET6 sockets.
  ...
2008-07-20 17:43:29 -07:00
Linus Torvalds
f7df406dce Merge branch 'configfs-fixup-ptr-error' of git://oss.oracle.com/git/jlbec/linux-2.6
* 'configfs-fixup-ptr-error' of git://oss.oracle.com/git/jlbec/linux-2.6:
  configfs: Allow ->make_item() and ->make_group() to return detailed errors.
  Revert "configfs: Allow ->make_item() and ->make_group() to return detailed errors."
2008-07-20 17:17:52 -07:00
Alan Cox
44b7d1b37f tty: add more tty_port fields
Move more bits into the tty_port structure

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:38 -07:00
Alan Cox
77451e53e0 cyclades: use tty_port
Switch cyclades to use the new tty_port structure

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:38 -07:00
Alan Cox
f8ae476416 stallion: use tty_port
Switch the stallion driver to use the tty_port structure

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:37 -07:00
Alan Cox
b02f5ad6a3 istallion: use tty_port
Switch istallion to use the new tty_port structure

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:37 -07:00
Alan Cox
b5391e29f4 gs: use tty_port
Switch drivers using the old "generic serial" driver to use the tty_port
structures

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:36 -07:00
Alan Cox
4982d6b37a esp: use tty_port
Switch esp to use the new tty_port structures

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:36 -07:00
Alan Cox
7a4d29f426 tty.h: clean up
Coding style clean up and white space tidy

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:36 -07:00
Alan Cox
df4f4dd429 serial: use tty_port
Switch the serial_core based drivers to use the new tty_port structure.
We can't quite use all of it yet because of the dynamically allocated
extras in the serial_core layer.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:35 -07:00
Alan Cox
6f67048cd0 tty: Introduce a tty_port common structure
Every tty driver has its own concept of a port structure and because
they all differ we cannot extract commonality.  Begin fixing this by
creating a structure drivers can elect to use so that over time we can
push fields into this and create commonality and then introduce common
methods.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:35 -07:00
Alan Cox
a352def21a tty: Ldisc revamp
Move the line disciplines towards a conventional ->ops arrangement.  For
the moment the actual 'tty_ldisc' struct in the tty is kept as part of
the tty struct but this can then be changed if it turns out that when it
all settles down we want to refcount ldiscs separately to the tty.

Pull the ldisc code out of /proc and put it with our ldisc code.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:34 -07:00
Haavard Skinnemoen
6bb0e3a59a Subject: [PATCH 1/2] serial: Add flush_buffer() operation to uart_ops
Serial drivers using DMA (like the atmel_serial driver) tend to get very
confused when the xmit buffer is flushed and nobody told them.  They
also tend to spew a lot of garbage since the DMA engine keeps running
after the buffer is flushed and possibly refilled with unrelated data.

This patch adds a new flush_buffer operation to the uart_ops struct,
along with a call to it from uart_flush_buffer() right after the xmit
buffer has been cleared. The driver can implement this in order to
syncronize its internal DMA state with the xmit buffer when the buffer
is flushed.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:34 -07:00
Philipp Zabel
99cdb0c8c5 mfd: let asic3 use mem resource instead of bus_shift
The bus_shift parameter in platform_data is not needed
as we can tell the driver with the IOMEM_RESOURCE whether
the ASIC is located on a 16bit or 32bit memory bus.

The htc-egpio driver uses a more descriptive bus_width parameter,
but for drivers where the register map size fixed, we don't even
need this.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
2008-07-20 19:56:44 +02:00
Philipp Zabel
279cac484e mfd: remove DS1WM register definitions from asic3.h
There is a dedicated ds1wm driver, no need to duplicate this
information here.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
2008-07-20 19:56:24 +02:00
Philipp Zabel
4a67b528e0 mfd: add ASIC3_CONFIG_GPIO templates
As ASIC3 GPIO alternate function configuration is expected to be similar
for several devices, it is convenient to define descriptive macros. This
patch is inspired by the PXA MFP configuration, the alternate functions
were observed on hx4700 and blueangel.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
2008-07-20 19:56:19 +02:00
Samuel Ortiz
3b8139f8b1 mfd: Use uppercase only for asic3 macros and defines
Let's be consistent and use uppercase only, for both macro and defines.

Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2008-07-20 19:55:14 +02:00
Samuel Ortiz
3b26bf1722 mfd: New asic3 gpio configuration code
The ASIC3 GPIO configuration code is a bit obscure and hardly readable.
This patch changes it so that it is now more readable and understandable,
by being more explicit.

Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2008-07-20 19:55:00 +02:00
Samuel Ortiz
1effe5bc6c mfd: asic3 children platform data removal
Platform devices should be dynamically allocated, and each supported
device should have its own platform data.
For now we just remove this buggy code.

Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2008-07-20 19:54:51 +02:00
Samuel Ortiz
6f2384c4bd mfd: asic3 gpiolib support
ASIC3 is, among other things, a GPIO extender. We should thus have it
supporting the current gpiolib API.

Signed-off-by: Samuel Ortiz <sameo@openedhand.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2008-07-20 19:52:38 +02:00
Jean Delvare
5a367dfb73 V4L/DVB (8246): tvaudio: Stop I2C driver ID abuse
The tvaudio driver is using "official" I2C device IDs for internal
purpose. There must be some historical reason behind this but anyway,
it shouldn't do that. As the stored values are never used, the easiest
way to fix the problem is simply to remove them altogether.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-07-20 07:18:38 -03:00
Jean Delvare
be99af6679 V4L/DVB (8245): ovcamchip: Delete stray I2C bus ID
I2C_HW_SMBUS_OVFX2 is referenced in ovcamchip_core.c, but no bus uses
this driver ID, so we can remove the reference. As far as I can see,
the Cypress FX2 webcam is handled by a different driver (dvb-usb).

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-07-20 07:18:34 -03:00
Hans de Goede
ab8f12cf8e V4L/DVB (8197): gspca: pac207 frames no more decoded in the subdriver.
videodev2: New pixfmt
pac207:   Remove the specific decoding.
main:     get_buff_size operation added for the subdriver.

Signed-off-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-07-20 07:17:02 -03:00
Hans de Goede
54ab92ca05 V4L/DVB (8194): gspca: Fix the format of the low resolution mode of spca561.
The low (half) res modes of the spca561 are not spca561 compressed, but are
raw bayer, this patches fixes this and adds a PIX_FMT define for the GBRG
bayer format used by the spca561 in low res mode.

Signed-off-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-07-20 07:16:47 -03:00
Jean-Francois Moine
6a7eba24e4 V4L/DVB (8157): gspca: all subdrivers
- remaning subdrivers added
- remove the decoding helper and some specific frame decodings

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-07-20 07:14:49 -03:00
Tobias Lorenz
1d0ba5f378 V4L/DVB (7942): Hardware frequency seek ioctl interface
Signed-off-by: Tobias Lorenz <tobias.lorenz@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
2008-07-20 07:07:12 -03:00
Marcelo Tosatti
34d4cb8fca KVM: MMU: nuke shadowed pgtable pages and ptes on memslot destruction
Flush the shadow mmu before removing regions to avoid stale entries.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20 12:42:40 +03:00
Tan, Li
9ef621d3be KVM: Support mixed endian machines
Currently kvmtrace is not portable. This will prevent from copying a
trace file from big-endian target to little-endian workstation for analysis.
In the patch, kernel outputs metadata containing a magic number to trace
log, and changes 64-bit words to be u64 instead of a pair of u32s.

Signed-off-by: Tan Li <li.tan@intel.com>
Acked-by: Jerone Young <jyoung5@us.ibm.com>
Acked-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20 12:42:32 +03:00
Laurent Vivier
5f94c1741b KVM: Add coalesced MMIO support (common part)
This patch adds all needed structures to coalesce MMIOs.
Until an architecture uses it, it is not compiled.

Coalesced MMIO introduces two ioctl() to define where are the MMIO zones that
can be coalesced:

- KVM_REGISTER_COALESCED_MMIO registers a coalesced MMIO zone.
  It requests one parameter (struct kvm_coalesced_mmio_zone) which defines
  a memory area where MMIOs can be coalesced until the next switch to
  user space. The maximum number of MMIO zones is KVM_COALESCED_MMIO_ZONE_MAX.

- KVM_UNREGISTER_COALESCED_MMIO cancels all registered zones inside
  the given bounds (bounds are also given by struct kvm_coalesced_mmio_zone).

The userspace client can check kernel coalesced MMIO availability by asking
ioctl(KVM_CHECK_EXTENSION) for the KVM_CAP_COALESCED_MMIO capability.
The ioctl() call to KVM_CAP_COALESCED_MMIO will return 0 if not supported,
or the page offset where will be stored the ring buffer.
The page offset depends on the architecture.

After an ioctl(KVM_RUN), the first page of the KVM memory mapped points to
a kvm_run structure. The offset given by KVM_CAP_COALESCED_MMIO is
an offset to the coalesced MMIO ring expressed in PAGE_SIZE relatively
to the address of the start of th kvm_run structure. The MMIO ring buffer
is defined by the structure kvm_coalesced_mmio_ring.

[akio: fix oops during guest shutdown]

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20 12:42:31 +03:00
Laurent Vivier
92760499d0 KVM: kvm_io_device: extend in_range() to manage len and write attribute
Modify member in_range() of structure kvm_io_device to pass length and the type
of the I/O (write or read).

This modification allows to use kvm_io_device with coalesced MMIO.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20 12:42:30 +03:00
Avi Kivity
7cc8883074 KVM: Remove decache_vcpus_on_cpu() and related callbacks
Obsoleted by the vmx-specific per-cpu list.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20 12:42:25 +03:00
Mike Travis
80422d3431 cpumask: Provide a generic set of CPUMASK_ALLOC macros, FIXUP
* Rename CPUMASK_VAR --> CPUMASK_PTR (and simplify)

  * Fix a semantic error in CPUMASK_ALLOC

  * Add a bit of commentry to cpumask.h

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-20 10:21:12 +02:00
Jussi Kivilinna
175f9c1bba net_sched: Add size table for qdiscs
Add size table functions for qdiscs and calculate packet size in
qdisc_enqueue().

Based on patch by Patrick McHardy
 http://marc.info/?l=linux-netdev&m=115201979221729&w=2

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-20 00:08:47 -07:00
YOSHIFUJI Hideaki
230b183921 net: Use standard structures for generic socket address structures.
Use sockaddr_storage{} for generic socket address storage
and ensures proper alignment.
Use sockaddr{} for pointers to omit several casts.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-19 22:35:47 -07:00
Adam Langley
4389dded77 tcp: Remove redundant checks when setting eff_sacks
Remove redundant checks when setting eff_sacks and make the number of SACKs a
compile time constant. Now that the options code knows how many SACK blocks can
fit in the header, we don't need to have the SACK code guessing at it.

Signed-off-by: Adam Langley <agl@imperialviolet.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-19 00:07:02 -07:00
David S. Miller
3072367300 pkt_sched: Manage qdisc list inside of root qdisc.
Idea is from Patrick McHardy.

Instead of managing the list of qdiscs on the device level, manage it
in the root qdisc of a netdev_queue.  This solves all kinds of
visibility issues during qdisc destruction.

The way to iterate over all qdiscs of a netdev_queue is to visit
the netdev_queue->qdisc, and then traverse it's list.

The only special case is to ignore builting qdiscs at the root when
dumping or doing a qdisc_lookup().  That was not needed previously
because builtin qdiscs were not added to the device's qdisc_list.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-18 22:50:15 -07:00
Matthew Garrett
92c4989092 Input: add switch for dock events
Add a SW_DOCK switch to input.h.  ACPI docks currently send their docking
status as a uevent, but not all docks are ACPI or correspond to a device.
In that case, it makes more sense to simply generate an input event on
docking or undocking.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2008-07-19 00:52:43 -04:00
Mark Brown
5ec461d083 Input: add microphone insert switch definition
Add a new switch type to the input API for reporting microphone
insertion. This will be used by the ALSA jack reporting API.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2008-07-19 00:52:36 -04:00
Patrick McHardy
8913336a7e packet: add PACKET_RESERVE sockopt
Add new sockopt to reserve some headroom in the mmaped ring frames in
front of the packet payload. This can be used f.i. when the VLAN header
needs to be (re)constructed to avoid moving the entire payload.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-18 18:05:19 -07:00
venkatesh.pallipadi@intel.com
ae79cdaacb x86: Add a arch directory for x86 under debugfs
Add a directory for x86 arch under debugfs. Can be used to accumulate all
x86 specific debugfs files.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-07-18 17:22:04 -07:00
Ingo Molnar
a208f37a46 Merge branch 'linus' into x86/x2apic 2008-07-18 22:50:34 +02:00
Mike Travis
77586c2bda cpumask: Provide a generic set of CPUMASK_ALLOC macros
* Provide a generic set of CPUMASK_ALLOC macros patterned after the
    SCHED_CPUMASK_ALLOC macros.  This is used where multiple cpumask_t
    variables are declared on the stack to reduce the amount of stack
    space required.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 22:03:00 +02:00
Mike Travis
65c0118453 cpumask: Replace cpumask_of_cpu with cpumask_of_cpu_ptr
* This patch replaces the dangerous lvalue version of cpumask_of_cpu
    with new cpumask_of_cpu_ptr macros.  These are patterned after the
    node_to_cpumask_ptr macros.

    In general terms, if there is a cpumask_of_cpu_map[] then a pointer to
    the cpumask_of_cpu_map[cpu] entry is used.  The cpumask_of_cpu_map
    is provided when there is a large NR_CPUS count, reducing
    greatly the amount of code generated and stack space used for
    cpumask_of_cpu().  The pointer to the cpumask_t value is needed for
    calling set_cpus_allowed_ptr() to reduce the amount of stack space
    needed to pass the cpumask_t value.

    If there isn't a cpumask_of_cpu_map[], then a temporary variable is
    declared and filled in with value from cpumask_of_cpu(cpu) as well as
    a pointer variable pointing to this temporary variable.  Afterwards,
    the pointer is used to reference the cpumask value.  The compiler
    will optimize out the extra dereference through the pointer as well
    as the stack space used for the pointer, resulting in identical code.

    A good example of the orthogonal usages is in net/sunrpc/svc.c:

	case SVC_POOL_PERCPU:
	{
		unsigned int cpu = m->pool_to[pidx];
		cpumask_of_cpu_ptr(cpumask, cpu);

		*oldmask = current->cpus_allowed;
		set_cpus_allowed_ptr(current, cpumask);
		return 1;
	}
	case SVC_POOL_PERNODE:
	{
		unsigned int node = m->pool_to[pidx];
		node_to_cpumask_ptr(nodecpumask, node);

		*oldmask = current->cpus_allowed;
		set_cpus_allowed_ptr(current, nodecpumask);
		return 1;
	}

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 22:02:57 +02:00
Ingo Molnar
bb2c018b09 Merge branch 'linus' into cpus4096
Conflicts:

	drivers/acpi/processor_throttling.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 22:00:54 +02:00
Ingo Molnar
9b610fda0d Merge branch 'linus' into timers/nohz 2008-07-18 19:53:16 +02:00
Ingo Molnar
3e370b29d3 Merge branch 'linus' into x86/pci-ioapic-boot-irq-quirks
Conflicts:

	drivers/pci/quirks.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 19:31:12 +02:00
Thomas Gleixner
b8f8c3cf0a nohz: prevent tick stop outside of the idle loop
Jack Ren and Eric Miao tracked down the following long standing
problem in the NOHZ code:

	scheduler switch to idle task
	enable interrupts

Window starts here

	----> interrupt happens (does not set NEED_RESCHED)
	      	irq_exit() stops the tick

	----> interrupt happens (does set NEED_RESCHED)

	return from schedule()
	
	cpu_idle(): preempt_disable();

Window ends here

The interrupts can happen at any point inside the race window. The
first interrupt stops the tick, the second one causes the scheduler to
rerun and switch away from idle again and we end up with the tick
disabled.

The fact that it needs two interrupts where the first one does not set
NEED_RESCHED and the second one does made the bug obscure and extremly
hard to reproduce and analyse. Kudos to Jack and Eric.

Solution: Limit the NOHZ functionality to the idle loop to make sure
that we can not run into such a situation ever again.

cpu_idle()
{
	preempt_disable();

	while(1) {
		 tick_nohz_stop_sched_tick(1); <- tell NOHZ code that we
		 			          are in the idle loop

		 while (!need_resched())
		       halt();

		 tick_nohz_restart_sched_tick(); <- disables NOHZ mode
		 preempt_enable_no_resched();
		 schedule();
		 preempt_disable();
	}
}

In hindsight we should have done this forever, but ... 

/me grabs a large brown paperbag.

Debugged-by: Jack Ren <jack.ren@marvell.com>, 
Debugged-by: eric miao <eric.y.miao@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-07-18 18:10:28 +02:00
Lai Jiangshan
5127bed588 rcu classic: new algorithm for callbacks-processing(v2)
This is v2, it's a little deference from v1 that I
had send to lkml.
use ACCESS_ONCE
use rcu_batch_after/rcu_batch_before for batch # comparison.

rcutorture test result:
(hotplugs: do cpu-online/offline once per second)

No CONFIG_NO_HZ:           OK, 12hours
No CONFIG_NO_HZ, hotplugs: OK, 12hours
CONFIG_NO_HZ=y:            OK, 24hours
CONFIG_NO_HZ=y, hotplugs:  Failed.
(Failed also without my patch applied, exactly the same bug occurred,
http://lkml.org/lkml/2008/7/3/24)

v1's email thread:
http://lkml.org/lkml/2008/6/2/539

v1's description:

The code/algorithm of the implement of current callbacks-processing
is very efficient and technical. But when I studied it and I found
a disadvantage:

In multi-CPU systems, when a new RCU callback is being
queued(call_rcu[_bh]), this callback will be invoked after the grace
period for the batch with batch number = rcp->cur+2 has completed
very very likely in current implement. Actually, this callback can be
invoked after the grace period for the batch with
batch number = rcp->cur+1 has completed. The delay of invocation means
that latency of synchronize_rcu() is extended. But more important thing
is that the callbacks usually free memory, and these works are delayed
too! it's necessary for reclaimer to free memory as soon as
possible when left memory is few.

A very simple way can solve this problem:
a field(struct rcu_head::batch) is added to record the batch number for
the RCU callback. And when a new RCU callback is being queued, we
determine the batch number for this callback(head->batch = rcp->cur+1)
and we move this callback to rdp->donelist if we find
that head->batch <= rcp->completed when we process callbacks.
This simple way reduces the wait time for invocation a lot. (about
2.5Grace Period -> 1.5Grace Period in average in multi-CPU systems)

This is my algorithm. But I do not add any field for struct rcu_head
in my implement. We just need to memorize the last 2 batches and
their batch number, because these 2 batches include all entries that
for whom the grace period hasn't completed. So we use a special
linked-list rather than add a field.
Please see the comment of struct rcu_data.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Gautham Shenoy <ego@in.ibm.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 16:07:33 +02:00
Lai Jiangshan
3cac97cbb1 rcu classic: simplify the next pending batch
use a batch number(rcp->pending) instead of a flag(rcp->next_pending)

rcu_start_batch() need to change this flag, so mb()s is needed
for memory-access safe.

but(after this patch applied) rcu_start_batch() do not change
this batch number(rcp->pending), rcp->pending is managed by
__rcu_process_callbacks only, and troublesome mb()s are eliminated.

And codes look simpler and clearer.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Gautham Shenoy <ego@in.ibm.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-18 16:07:32 +02:00