sysfs allows attribute files to be truncated, e.g. using ftruncate(), with the
expected effect on their inode.   For most attributes, this doesn't change the
"real" size of the file i.e. how much can be read from it.  However, the
parameter validation for reading and writing binary attribute files is based
on the inode size and not the size specified in the file's bin_attribute, so it
can be broken by this. For example, if we try using dd to write to such a file:

# pwd
/sys/bus/pci/devices/0000:08:00.0
# ls -l config
-rw-r--r--  1 root root 4096 Feb  1 17:35 config
# dd if=/dev/zero of=config bs=4 count=1
1+0 records in
1+0 records out
# ls -l config
-rw-r--r--  1 root root 0 Feb  1 17:50 config
# dd if=/dev/zero of=config bs=4 count=1 seek=128
dd: writing `config': No space left on device
1+0 records in
0+0 records out

Also, after truncation to 0, parameter validation for read and write is
disabled.  Most bin_attribute read and write methods also validate the size and
offset, but for some this will allow out-of-range access.  This may be a
security issue, though access to such files is often limited to root.  In any
case, the validation should remain for safety's sake!)

This was previously reported in Bugzilla as bug 9867.

sysfs should ignore size changes or else refuse them (by returning -EINVAL).
This patch makes it ignore them.
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (179 commits)
  ACPI: Fix acpi_processor_idle and idle= boot parameters interaction
  acpi: fix section mismatch warning in pnpacpi
  intel_menlo: fix build warning
  ACPI: Cleanup: Remove unneeded, multiple local dummy variables
  ACPI: video - fix permissions on some proc entries
  ACPI: video - properly handle errors when registering proc elements
  ACPI: video - do not store invalid entries in attached_array list
  ACPI: re-name acpi_pm_ops to acpi_suspend_ops
  ACER_WMI/ASUS_LAPTOP: fix build bug
  thinkpad_acpi: fix possible NULL pointer dereference if kstrdup failed
  ACPI: check a return value correctly in acpi_power_get_context()
  #if 0 acpi/bay.c:eject_removable_drive()
  eeepc-laptop: add hwmon fan control
  eeepc-laptop: add backlight
  eeepc-laptop: add base driver
  ACPI: thinkpad-acpi: bump up version to 0.20
  ACPI: thinkpad-acpi: fix selects in Kconfig
  ACPI: thinkpad-acpi: use a private workqueue
  ACPI: thinkpad-acpi: fluff really minor fix
  ACPI: thinkpad-acpi: use uppercase for "LED" on user documentation
  ...

Fixed conflicts in drivers/acpi/video.c and drivers/misc/intel_menlow.c
manually.

Merge branches 'release', 'acpica', 'bugzilla-10224', 'bugzilla-9772', 'bugzilla-9916', 'ec', 'eeepc', 'idle', 'misc', 'pm-legacy', 'sysfs-links-2.6.26', 'thermal', 'thinkpad' and 'video' into release

acpi_processor_idle and "idle=" boot parameter interaction is broken.
The problem is that, at boot time acpi driver is checking for "idle=" boot
option and not registering the acpi idle handler. But, when there is a CST
changed callback (typically when switching AC <-> battery or suspend-resume)
there are no checks for boot_option_idle_override and acpi idle handler tries
to get installed with nasty side effects.

With CPU_IDLE configured this issue causes results in a nasty oops on CST
change callback and without CPU_IDLE there is no oops, but boot option
of "idle=" gets ignored and acpi idle handler gets installed.

Change the behavior to not do anything in acpi idle handler when there is a
"idle=" boot option.

Note that the problem is only there when "idle=" boot option is used.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Fix following section mismatch warning:
WARNING: vmlinux.o(.text+0x153d69): Section mismatch in reference from the function is_exclusive_device() to the variable .init.data:excluded_id_list

is_exclusive_device is only used from __init context so document
this with the __init annotation and get rid of the warning.
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NLen Brown <len.brown@intel.com>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  [ALSA] soc - neo1973_wm8753.c add suspend and shutdown hooks for lm4857 chip
  [ALSA] soc - neo1973_wm8753.c change maintainer contact info
  [ALSA] soc - neo1973_wm8753.c cleanup checkpatch issues
  [ALSA] soc - ln2440sbc_alc650 - Fix checkpatch warnings
  [ALSA] soc - s3c24xx-pcm - Fix checkpatch warnings
  [ALSA] soc - s3c2443-ac97 - Fix checkpatch warnings
  [ALSA] soc - wm8753 - Clean up checkpatch warnings

Patch taken from the openmoko bugtracker
http://bugzilla.openmoko.org/cgi-bin/bugzilla/show_bug.cgi?id=781

This patch adds Suspend/Resume and Shutdown support for the lm4857 to
the driver.
Signed-off-by: NGraeme Gregory <graeme@openmoko.org>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

I have moved workplaces since I originally wrote this driver so update
the contact info for new employers.
Signed-off-by: NGraeme Gregory <graeme@openmoko.org>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Clean up a few issues with the file that checkpatch noted, no functionality
changes.
Signed-off-by: NGraeme Gregory <graeme@openmoko.org>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
  sparc64: remove duplicated include
  sparc: Add kgdb support.
  kgdbts: Sparc needs sstep emulation.
  sparc32: Kill smp_message_pass() and related code.
  sparc64: Kill PIL_RESERVED, unused.
  sparc64: Split entry.S up into seperate files.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (53 commits)
  tcp: Overflow bug in Vegas
  [IPv4] UFO: prevent generation of chained skb destined to UFO device
  iwlwifi: move the selects to the tristate drivers
  ipv4: annotate a few functions __init in ipconfig.c
  atm: ambassador: vcc_sf semaphore to mutex
  MAINTAINERS: The socketcan-core list is subscribers-only.
  netfilter: nf_conntrack: padding breaks conntrack hash on ARM
  ipv4: Update MTU to all related cache entries in ip_rt_frag_needed()
  sch_sfq: use del_timer_sync() in sfq_destroy()
  net: Add compat support for getsockopt (MCAST_MSFILTER)
  net: Several cleanups for the setsockopt compat support.
  ipvs: fix oops in backup for fwmark conn templates
  bridge: kernel panic when unloading bridge module
  bridge: fix error handling in br_add_if()
  netfilter: {nfnetlink,ip,ip6}_queue: fix skb_over_panic when enlarging packets
  netfilter: x_tables: fix net namespace leak when reading /proc/net/xxx_tables_names
  netfilter: xt_TCPOPTSTRIP: signed tcphoff for ipv6_skip_exthdr() retval
  tcp: Limit cwnd growth when deferring for GSO
  tcp: Allow send-limited cwnd to grow up to max_burst when gso disabled
  [netdrvr] gianfar: Determine TBIPA value dynamically
  ...

fix the condition to match intention: always use the old inlining
behavior on all gcc versions below 4.

this should solve the UML build problem.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I realize some of the maintainers email clients and/or scripts cannot
handle UTF-8 encoded names properly, as a result your ChangeLogs
displays me as two different person :).

Following patch adds correctly encoded name of mine into .mailmap, to
prevent appearing it not to be so or badly displayed.
Signed-off-by: NS.Çağlar Onur <caglar@pardus.org.tr>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
  [S390] Update default configuration.
  [S390] use generic sys_ptrace
  [S390] Remove self ptrace IEEE_IP hack.
  [S390] Convert to SPARSEMEM & SPARSEMEM_VMEMMAP
  [S390] System z large page support.
  [S390] Convert machine feature detection code to C.
  [S390] vmemmap: use clear_table to initialise page tables.
  [S390] Move stfl to system.h and delete duplicated version.
  [S390] uaccess_mvcos: #ifdef config dependent code.
  [S390] cpu topology: Fix possible deadlock.
  [S390] Add topology_core_siblings to topology.h
  [S390] cio: Make isc handling more robust.
  [S390] remove -traditional
  [S390] Automatically detect added cpus.
  [S390] smp: Fix locking order.
  [S390] Add missing ifndef/define to include/asm-s390/sysinfo.h.
  [S390] Move show_regs to traps.c.
  [S390] cio: Use strict_strtoul() for attributes.

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
  [POWERPC] Fix crashkernel= handling when no crashkernel= specified
  [POWERPC] Make emergency stack safe for current_thread_info() use
  [POWERPC] spufs: add .gitignore for spu_save_dump.h & spu_restore_dump.h
  [POWERPC] spufs: trace spu_acquire_saved events
  [POWERPC] spufs: fix marker name for find_victim
  [POWERPC] spufs: add marker for destroy_spu_context
  [POWERPC] spufs: add sputrace marker parameter names
  [POWERPC] spufs: add context switch notification log
  [POWERPC] mpc5200: defconfigs for CM5200, Lite5200B, Motion-PRO and TQM5200
  [POWERPC] mpc5200: Switch mpc5200 dts files to dts-v1 format
  [POWERPC] mpc5200: Fix FEC error handling on FIFO errors
  [POWERPC] mpc5200: add Phytec pcm030 board support
  [POWERPC] mpc5200: add gpiolib support for mpc5200
  [POWERPC] mpc5200: add interrupt type function
  [POWERPC] mpc5200: Fix unterminated of_device_id table

x86.git randconfig testing found a build failure on latest -git:

 drivers/built-in.o: In function `set_type':
 tuner-core.c:(.text+0x2a9a26): undefined reference to `tea5761_attach'
 tuner-core.c:(.text+0x2a9d05): undefined reference to `tda9887_attach'
 tuner-core.c:(.text+0x2a9d51): undefined reference to `xc2028_attach'
 tuner-core.c:(.text+0x2a9e22): undefined reference to `tda829x_attach'
 tuner-core.c:(.text+0x2a9e3f): undefined reference to `microtune_attach'
 drivers/built-in.o: In function `tuner_probe':
 tuner-core.c:(.text+0x2aa18a): undefined reference to `tda829x_probe'
 tuner-core.c:(.text+0x2aa302): undefined reference to `tea5761_autodetection'

with the following config:

 http://redhat.com/~mingo/misc/config-Wed_Apr_30_10_21_40_CEST_2008.bad

the problem is caused by the drivers/media/common/tuners/ subdirectory
not being part of the kbuild hierarchy anymore, due to commit
7c91f062 ("V4L/DVB(7767): Move tuners to common/tuners").

this seems similar to the problem also reported by Mike Galbraith.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This:

commit 86f6dae1
Author: Yasunori Goto <y-goto@jp.fujitsu.com>
Date:   Mon Apr 28 02:13:33 2008 -0700

    memory hotplug: allocate usemap on the section with pgdat

    Usemaps are allocated on the section which has pgdat by this.

    Because usemap size is very small, many other sections usemaps are allocated
    on only one page.  If a section has usemap, it can't be removed until removing
    other sections.  This dependency is not desirable for memory removing.

    Pgdat has similar feature.  When a section has pgdat area, it must be the last
    section for removing on the node.  So, if section A has pgdat and section B
    has usemap for section A, Both sections can't be removed due to dependency
    each other.

    To solve this issue, this patch collects usemap on same section with pgdat.
    If other sections doesn't have any dependency, this section will be able to be
    removed finally.
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
    Cc: Badari Pulavarty <pbadari@us.ibm.com>
    Cc: Yinghai Lu <yhlu.kernel@gmail.com>
    Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

broke davem's sparc64 bootup.  Revert it while we work out what went wrong.

Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

KAMEZAWA Hiroyuki found a warning message in the buffer dirtying code that
is coming from page migration caller.

WARNING: at fs/buffer.c:720 __set_page_dirty+0x330/0x360()
Call Trace:
 [<a000000100015220>] show_stack+0x80/0xa0
 [<a000000100015270>] dump_stack+0x30/0x60
 [<a000000100089ed0>] warn_on_slowpath+0x90/0xe0
 [<a0000001001f8b10>] __set_page_dirty+0x330/0x360
 [<a0000001001ffb90>] __set_page_dirty_buffers+0xd0/0x280
 [<a00000010012fec0>] set_page_dirty+0xc0/0x260
 [<a000000100195670>] migrate_page_copy+0x5d0/0x5e0
 [<a000000100197840>] buffer_migrate_page+0x2e0/0x3c0
 [<a000000100195eb0>] migrate_pages+0x770/0xe00

What was happening is that migrate_page_copy wants to transfer the PG_dirty
bit from old page to new page, so what it would do is set_page_dirty(newpage).
However set_page_dirty() is used to set the entire page dirty, wheras in
this case, only part of the page was dirty, and it also was not uptodate.

Marking the whole page dirty with set_page_dirty would lead to corruption or
unresolvable conditions -- a dirty && !uptodate page and dirty && !uptodate
buffers.

Possibly we could just ClearPageDirty(oldpage); SetPageDirty(newpage);
however in the interests of keeping the change minimal...
Signed-off-by: NNick Piggin <npiggin@suse.de>
Tested-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix up the contents of <linux/byteorder/> so that it doesn't export a
content-free generic.h to user space.  This involves:

* Removing the __KERNEL__ tests from generic.h and dropping it from
  Kbuild.
* Wrapping the inclusions of generic.h in both big_endian.h and
  little_endian.h in __KERNEL__ tests.
* Shifting big_endian.h and little_endian.h from header-y to
  unifdef-y in Kbuild.
Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the "#ifdef __KERNEL__" tests from unexported header files in
linux/include whose entire contents are wrapped in that preprocessor
test.
Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__FUNCTION__ is gcc specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds partition management for Block RAM Device (BRD).

This patch is done to keep in sync BRD and loop device drivers.

This patch adds a parameter to the module, max_part, to specify
the maximum number of partitions per RAM device.

Example:

# modprobe brd max_part=63
# ls -l /dev/ram*
brw-rw---- 1 root disk 1,   0 2008-04-03 13:39 /dev/ram0
brw-rw---- 1 root disk 1,  64 2008-04-03 13:39 /dev/ram1
brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10
brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11
brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12
brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13
brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14
brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15
brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2
brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3
brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4
brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5
brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6
brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7
brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8
brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9
# fdisk /dev/ram0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
# ls -l /dev/ram0*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0
brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1
# mkfs /dev/ram0p1
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4016 inodes, 16032 blocks
801 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=16515072
2 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
	8193

Writing inode tables: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
# mount /dev/ram0p1 /mnt
df /mnt
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/ram0p1              15521       138     14582   1% /mnt
# ls -l /mnt
total 12
drwx------ 2 root root 12288 2008-04-03 13:41 lost+found
# umount /mnt
# rmmod brd
Signed-off-by: NLaurent Vivier <Laurent.Vivier@bull.net>
Acked-by: NNick Piggin <nickpiggin@yahoo.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

hrtimers have now dynamic users in the network code.  Put them under
debugobjects surveillance as well.

Add calls to the generic object debugging infrastructure and provide fixup
functions which allow to keep the system alive when recoverable problems have
been detected by the object debugging core code.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add calls to the generic object debugging infrastructure and provide fixup
functions which allow to keep the system alive when recoverable problems have
been detected by the object debugging core code.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a DocBook for debugobjects.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We can see an ever repeating problem pattern with objects of any kind in the
kernel:

1) freeing of active objects
2) reinitialization of active objects

Both problems can be hard to debug because the crash happens at a point where
we have no chance to decode the root cause anymore.  One problem spot are
kernel timers, where the detection of the problem often happens in interrupt
context and usually causes the machine to panic.

While working on a timer related bug report I had to hack specialized code
into the timer subsystem to get a reasonable hint for the root cause.  This
debug hack was fine for temporary use, but far from a mergeable solution due
to the intrusiveness into the timer code.

The code further lacked the ability to detect and report the root cause
instantly and keep the system operational.

Keeping the system operational is important to get hold of the debug
information without special debugging aids like serial consoles and special
knowledge of the bug reporter.

The problems described above are not restricted to timers, but timers tend to
expose it usually in a full system crash.  Other objects are less explosive,
but the symptoms caused by such mistakes can be even harder to debug.

Instead of creating specialized debugging code for the timer subsystem a
generic infrastructure is created which allows developers to verify their code
and provides an easy to enable debug facility for users in case of trouble.

The debugobjects core code keeps track of operations on static and dynamic
objects by inserting them into a hashed list and sanity checking them on
object operations and provides additional checks whenever kernel memory is
freed.

The tracked object operations are:
- initializing an object
- adding an object to a subsystem list
- deleting an object from a subsystem list

Each operation is sanity checked before the operation is executed and the
subsystem specific code can provide a fixup function which allows to prevent
the damage of the operation.  When the sanity check triggers a warning message
and a stack trace is printed.

The list of operations can be extended if the need arises.  For now it's
limited to the requirements of the first user (timers).

The core code enqueues the objects into hash buckets.  The hash index is
generated from the address of the object to simplify the lookup for the check
on kfree/vfree.  Each bucket has it's own spinlock to avoid contention on a
global lock.

The debug code can be compiled in without being active.  The runtime overhead
is minimal and could be optimized by asm alternatives.  A kernel command line
option enables the debugging code.

Thanks to Ingo Molnar for review, suggestions and cleanup patches.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a preperatory patch for the debugobjects infrastructure.  The flag
prevents debug_free checks on kmem_caches.  This is necessary to avoid
resursive calls into a debug mechanism which uses a kmem_cache itself.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>