Doing something like this on a two cpu system
# echo 0 > /sys/devices/system/cpu/cpu0/online
# echo 1 > /sys/devices/system/cpu/cpu0/online
# echo 0 > /sys/devices/system/cpu/cpu1/online
will give me this:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.21-rc2-g562aa1d4-dirty #7
-------------------------------------------------------
bash/1282 is trying to acquire lock:
(&cpu_base->lock_key){.+..}, at: [<000000000005f17e>] hrtimer_cpu_notify+0xc6/0x240
but task is already holding lock:
(&cpu_base->lock_key#2){.+..}, at: [<000000000005f174>] hrtimer_cpu_notify+0xbc/0x240
which lock already depends on the new lock.
This happens because we have the following code in kernel/hrtimer.c:
migrate_hrtimers(int cpu)
[...]
old_base = &per_cpu(hrtimer_bases, cpu);
new_base = &get_cpu_var(hrtimer_bases);
[...]
spin_lock(&new_base->lock);
spin_lock(&old_base->lock);
Which means the spinlocks are taken in an order which depends on which cpu
gets shut down from which other cpu. Therefore lockdep complains that there
might be an ABBA deadlock. Since migrate_hrtimers() gets only called on
cpu hotplug it's safe to assume that it isn't executed concurrently on a
The same problem exists in kernel/timer.c: migrate_timers().
As pointed out by Christian Borntraeger one possible solution to avoid
the locking order complaints would be to make sure that the locks are
always taken in the same order. E.g. by taking the lock of the cpu with
the lower number first.
To achieve this we introduce two new spinlock functions double_spin_lock
and double_spin_unlock which lock or unlock two locks in a given order.
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Christian Borntraeger <cborntra@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we do not check for vma flags if sys_move_pages is called to move
individual pages. If sys_migrate_pages is called to move pages then we
check for vm_flags that indicate a non migratable vma but that still
includes VM_LOCKED and we can migrate mlocked pages.
Extract the vma_migratable check from mm/mempolicy.c, fix it and put it
into migrate.h so that is can be used from both locations.
Problem was spotted by Lee Schermerhorn
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the SMT-nice feature which idles sibling cpus on SMT cpus to
facilitiate nice working properly where cpu power is shared. The idling of
cpus in the presence of runnable tasks is considered too fragile, easy to
break with outside code, and the complexity of managing this system if an
architecture comes along with many logical cores sharing cpu power will be
unworkable.
Remove the associated per_cpu_gain variable in sched_domains used only by
this code.
Also:
The reason is that with dynticks enabled, this code breaks without yet
further tweaks so dynticks brought on the rapid demise of this code. So
either we tweak this code or kill it off entirely. It was Ingo's preference
to kill it off. Either way this needs to happen for 2.6.21 since dynticks
has gone in.
Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In some cases when we are not using msi we need a way to ensure that the
hardware does not have an msi capability enabled. Currently the code has been
calling disable_msi_mode to try and achieve that. However disable_msi_mode
has several other side effects and is only available when msi support is
compiled in so it isn't really appropriate.
Instead this patch implements pci_msi_off which disables all msi and msix
capabilities unconditionally with no additional side effects.
pci_disable_device was redundantly clearing the bus master enable flag and
clearing the msi enable bit. A device that is not allowed to perform bus
mastering operations cannot generate intx or msi interrupt messages as those
are essentially a special case of dma, and require bus mastering. So the call
in pci_disable_device to disable msi capabilities was redundant.
quirk_pcie_pxh also called disable_msi_mode and is updated to use pci_msi_off.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6:
[VLAN]: Avoid a 4-order allocation.
[HDLC] Fix dev->header_cache_update having a random value.
[NetLabel]: Verify sensitivity level has a valid CIPSO mapping
[PPPOE]: Key connections properly on local device.
[AF_UNIX]: Test against sk_max_ack_backlog properly.
[NET]: Fix bugs in "Whether sock accept queue is full" checking
* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
[MIPS] MTX1: clear PCI errors
[MIPS] MTX1: add idsel cardbus ressources
[MIPS] MTX1: remove unneeded settings
[MIPS] dma_sync_sg_for_cpu is a no-op except for non-coherent R10000s.
[MIPS] Cobalt: update reserved resources
[MIPS] SN: PCI fixup needs to include <irq.h>.
[MIPS] DMA: Fix a bunch of warnings due to missing inline keywords.
[MIPS] RM: It should be #ifdef CONFIG_FOO not #if CONFIG_FOO ...
[MIPS] Fix and cleanup the mess that a dozen prom_printf variants are.
[MIPS] DEC: Remove redeclarations of mips_machgroup and mips_machtype.
[MIPS] No need to write c0_compare in plat_timer_setup
[MIPS] Convert to RTC-class ds1742 driver
[MIPS] Oprofile: Add missing break statements.
[MIPS] jmr3927: build fix
[MIPS] SNI: Fix mc146818_decode_year
[MIPS] Replace sys32_timer_create with the generic compat_sys_timer_create.
[MIPS] Replace sys32_socketcall with the generic compat_sys_socketcall.
[MIPS] N32 waitid is the same as o32.
The generic rtc-ds1742 driver can be used for RBTX4927 and JMR3927
(with __swizzle_addr trick). This patch also removes MIPS local
DS1742 stuff.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Allocate a distinct inode for every vcpu in a VM. This has the following
benefits:
- the filp cachelines are no longer bounced when f_count is incremented on
every ioctl()
- the API and internal code are distinctly clearer; for example, on the
KVM_GET_REGS ioctl, there is no need to copy the vcpu number from
userspace and then copy the registers back; the vcpu identity is derived
from the fd used to make the call
Right now the performance benefits are completely theoretical since (a) we
don't support more than one vcpu per VM and (b) virtualization hardware
inefficiencies completely everwhelm any cacheline bouncing effects. But
both of these will change, and we need to prepare the API today.
Signed-off-by: Avi Kivity <avi@qumranet.com>
This avoids having filp->f_op and the corresponding inode->i_fop different,
which is a little unorthodox.
The ioctl list is split into two: global kvm ioctls and per-vm ioctls. A new
ioctl, KVM_CREATE_VM, is used to create VMs and return the VM fd.
Signed-off-by: Avi Kivity <avi@qumranet.com>
This adds a special MSR based hypercall API to KVM. This is to be
used by paravirtual kernels and virtual drivers.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Avi Kivity <avi@qumranet.com>
The function ide_get_best_pio_mode() fails to return the correct IORDY setting
for the explicitly specified modes -- fix this along with the heading comment,
and also remove the long commented out code.
Also, while at it, correct the misliading comment about the PIO cycle time in
<linux/ide.h> -- it actually consists of only the active and recovery periods,
with only some chips also including the address setup time into equation...
[ bart: sl82c105 seems to be currently the only driver affected by this fix ]
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
This patch splits the vlan_group struct into a multi-allocated struct. On
x86_64, the size of the original struct is a little more than 32KB, causing
a 4-order allocation, which is prune to problems caused by buddy-system
external fragmentation conditions.
I couldn't just use vmalloc() because vfree() cannot be called in the
softirq context of the RCU callback.
Signed-off-by: Dan Aloni <da-x@monatomic.org>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The information contained within platform_data should be self-contained.
Replace the pointer to a MAC address with the actual MAC address in
struct mv643xx_eth_platform_data.
Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Conditionalize all PM related stuff in libata core layer using
CONFIG_PM.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
The initial simplex handling code is fooled if you suspend and resume.
This also causes problems with some single channel controllers which
claim to be simplex.
The fix is fairly simple, instead of keeping a flag to remember if we
gave away the simplex channel we remember the actual owner. As the owner
is always part of the host_set we don't even need a refcount.
Knowing the owner also means we can reassign simplex DMA channels in
future hotplug code etc if we need to
Signed-off-by: Alan Cox <alan@redhat.com>
(and a signed-off for the patch I sent before while I remember)
Signed-off-by: Jeff Garzik <jeff@garzik.org>
* 'for-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jikos/hid:
HID: fix Logitech DiNovo Edge touchwheel and Logic3 /SpectraVideo middle button
HID: add git tree information to MAINTAINERS
HID: fix broken Logitech S510 keyboard report descriptor; make extra keys work
HID: fix possible double-free on error path in hid parser
HID: hid-debug.c should #include <linux/hid-debug.h>
HID: fix bug in zeroing the last field byte in output reports
USB HID: use CONFIG_HID_DEBUG for outputting report descriptor
USB HID: Fix USB vendor and product IDs endianness for USB HID devices
