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  1. 24 5月, 2008 2 次提交
  3. 30 4月, 2008 1 次提交
    • T
      infrastructure to debug (dynamic) objects · 3ac7fe5a
      由 Thomas Gleixner 提交于 
      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>
      3ac7fe5a
  5. 29 4月, 2008 1 次提交
  7. 27 4月, 2008 1 次提交
    • A
      x86: generic versions of find_first_(zero_)bit, convert i386 · 77b9bd9c
      由 Alexander van Heukelum 提交于 
      Generic versions of __find_first_bit and __find_first_zero_bit
are introduced as simplified versions of __find_next_bit and
__find_next_zero_bit. Their compilation and use are guarded by
a new config variable GENERIC_FIND_FIRST_BIT.

The generic versions of find_first_bit and find_first_zero_bit
are implemented in terms of the newly introduced __find_first_bit
and __find_first_zero_bit.

This patch does not remove the i386-specific implementation,
but it does switch i386 to use the generic functions by setting
GENERIC_FIND_FIRST_BIT=y for X86_32.
Signed-off-by: NAlexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      77b9bd9c
  9. 17 4月, 2008 1 次提交
  11. 29 3月, 2008 1 次提交
  13. 14 2月, 2008 1 次提交
  15. 09 2月, 2008 1 次提交
  17. 06 2月, 2008 1 次提交
  19. 29 1月, 2008 1 次提交
  21. 28 1月, 2008 1 次提交
  23. 15 11月, 2007 1 次提交
  25. 20 10月, 2007 1 次提交
    • P
      Fix cpusets update_cpumask · 8707d8b8
      由 Paul Menage 提交于 
      Cause writes to cpuset "cpus" file to update cpus_allowed for member tasks:

- collect batches of tasks under tasklist_lock and then call
  set_cpus_allowed() on them outside the lock (since this can sleep).

- add a simple generic priority heap type to allow efficient collection
  of batches of tasks to be processed without duplicating or missing any
  tasks in subsequent batches.

- make "cpus" file update a no-op if the mask hasn't changed

- fix race between update_cpumask() and sched_setaffinity() by making
  sched_setaffinity() post-check that it's not running on any cpus outside
  cpuset_cpus_allowed().

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NPaul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8707d8b8
  27. 17 10月, 2007 1 次提交
  29. 13 10月, 2007 1 次提交
  31. 08 10月, 2007 1 次提交
  33. 23 8月, 2007 1 次提交
  35. 01 8月, 2007 1 次提交
  37. 18 7月, 2007 2 次提交
  39. 17 7月, 2007 2 次提交
  41. 11 7月, 2007 1 次提交
  43. 11 5月, 2007 2 次提交
    • R
      lib/hexdump · 99eaf3c4
      由 Randy Dunlap 提交于 
      Based on ace_dump_mem() from Grant Likely for the Xilinx SystemACE
CompactFlash interface.

Add print_hex_dump() & hex_dumper() to lib/hexdump.c and linux/kernel.h.

This patch adds the functions print_hex_dump() & hex_dumper().
print_hex_dump() can be used to perform a hex + ASCII dump of data to
syslog, in an easily viewable format, thus providing a common text hex dump
format.

hex_dumper() provides a dump-to-memory function.  It converts one "line" of
output (16 bytes of input) at a time.

Example usages:
	print_hex_dump(KERN_DEBUG, DUMP_PREFIX_ADDRESS, frame->data, frame->len);
	hex_dumper(frame->data, frame->len, linebuf, sizeof(linebuf));

Example output using %DUMP_PREFIX_OFFSET:
0009ab42: 40414243 44454647 48494a4b 4c4d4e4f-@ABCDEFG HIJKLMNO
Example output using %DUMP_PREFIX_ADDRESS:
ffffffff88089af0: 70717273 74757677 78797a7b 7c7d7e7f-pqrstuvw xyz{|}~.

[akpm@linux-foundation.org: cleanups, add export]
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      99eaf3c4
    • I
      CRC ITU-T V.41 · 3e7cbae7
      由 Ivo van Doorn 提交于 
      This will add the CRC calculation according
to the CRC ITU-T V.41 to the kernel lib/ folder.

This code has been derived from the rt2x00 driver,
currently found only in the wireless-dev tree, but
this library is generic and could be used by more
drivers who currently use their own implementation.
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>

Also useful for the new firewire stack.
Signed-off-by: NKristian Hoegsberg <krh@redhat.com>
Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>
      3e7cbae7
  45. 26 4月, 2007 1 次提交
  47. 12 2月, 2007 2 次提交
  49. 10 2月, 2007 2 次提交
    • T
      iomap: iomap should be in obj-y not in lib-y · ca299788
      由 Tejun Heo 提交于 
      devres change moved iomap.o from obj-$(CONFIG_GENERIC_IOMAP) to lib-y
making it not linked if no in-kernel driver uses it.  Fix it.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>
      ca299788
    • T
      devres: device resource management · 9ac7849e
      由 Tejun Heo 提交于 
      Implement device resource management, in short, devres.  A device
driver can allocate arbirary size of devres data which is associated
with a release function.  On driver detach, release function is
invoked on the devres data, then, devres data is freed.

devreses are typed by associated release functions.  Some devreses are
better represented by single instance of the type while others need
multiple instances sharing the same release function.  Both usages are
supported.

devreses can be grouped using devres group such that a device driver
can easily release acquired resources halfway through initialization
or selectively release resources (e.g. resources for port 1 out of 4
ports).

This patch adds devres core including documentation and the following
managed interfaces.

* alloc/free	: devm_kzalloc(), devm_kzfree()
* IO region	: devm_request_region(), devm_release_region()
* IRQ		: devm_request_irq(), devm_free_irq()
* DMA		: dmam_alloc_coherent(), dmam_free_coherent(),
		  dmam_declare_coherent_memory(), dmam_pool_create(),
		  dmam_pool_destroy()
* PCI		: pcim_enable_device(), pcim_pin_device(), pci_is_managed()
* iomap		: devm_ioport_map(), devm_ioport_unmap(), devm_ioremap(),
		  devm_ioremap_nocache(), devm_iounmap(), pcim_iomap_table(),
		  pcim_iomap(), pcim_iounmap()
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>
      9ac7849e
  51. 14 12月, 2006 2 次提交
    • A
      [PATCH] uml problems with linux/io.h · ee36c2bf
      由 Al Viro 提交于 
      Remove useless includes of linux/io.h, don't even try to build iomap_copy
on uml (it doesn't have readb() et.al., so...)
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Acked-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      ee36c2bf
    • E
      [PATCH] SLAB: use a multiply instead of a divide in obj_to_index() · 6a2d7a95
      由 Eric Dumazet 提交于 
      When some objects are allocated by one CPU but freed by another CPU we can
consume lot of cycles doing divides in obj_to_index().

(Typical load on a dual processor machine where network interrupts are
handled by one particular CPU (allocating skbufs), and the other CPU is
running the application (consuming and freeing skbufs))

Here on one production server (dual-core AMD Opteron 285), I noticed this
divide took 1.20 % of CPU_CLK_UNHALTED events in kernel.  But Opteron are
quite modern cpus and the divide is much more expensive on oldest
architectures :

On a 200 MHz sparcv9 machine, the division takes 64 cycles instead of 1
cycle for a multiply.

Doing some math, we can use a reciprocal multiplication instead of a divide.

If we want to compute V = (A / B)  (A and B being u32 quantities)
we can instead use :

V = ((u64)A * RECIPROCAL(B)) >> 32 ;

where RECIPROCAL(B) is precalculated to ((1LL << 32) + (B - 1)) / B

Note :

I wrote pure C code for clarity. gcc output for i386 is not optimal but
acceptable :

mull   0x14(%ebx)
mov    %edx,%eax // part of the >> 32
xor     %edx,%edx // useless
mov    %eax,(%esp) // could be avoided
mov    %edx,0x4(%esp) // useless
mov    (%esp),%ebx

[akpm@osdl.org: small cleanups]
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      6a2d7a95
  53. 09 12月, 2006 3 次提交
    • A
      [PATCH] fault-injection capabilities infrastructure · 6ff1cb35
      由 Akinobu Mita 提交于 
      This patch provides base functions implement to fault-injection
capabilities.

- The function should_fail() is taken from failmalloc-1.0
  (http://www.nongnu.org/failmalloc/)

[akpm@osdl.org: cleanups, comments, add __init]
Cc: <okuji@enbug.org>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NDon Mullis <dwm@meer.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      6ff1cb35
    • A
      [PATCH] bit reverse library · a5cfc1ec
      由 Akinobu Mita 提交于 
      This patch provides two bit reverse functions and bit reverse table.

- reverse the order of bits in a u32 value

	u8 bitrev8(u8 x);

- reverse the order of bits in a u32 value

	u32 bitrev32(u32 x);

- byte reverse table

	const u8 byte_rev_table[256];
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      a5cfc1ec
    • J
      [PATCH] Generic BUG implementation · 7664c5a1
      由 Jeremy Fitzhardinge 提交于 
      This patch adds common handling for kernel BUGs, for use by architectures as
they wish.  The code is derived from arch/powerpc.

The advantages of having common BUG handling are:
 - consistent BUG reporting across architectures
 - shared implementation of out-of-line file/line data
 - implement CONFIG_DEBUG_BUGVERBOSE consistently

This means that in inline impact of BUG is just the illegal instruction
itself, which is an improvement for i386 and x86-64.

A BUG is represented in the instruction stream as an illegal instruction,
which has file/line information associated with it.  This extra information is
stored in the __bug_table section in the ELF file.

When the kernel gets an illegal instruction, it first confirms it might
possibly be from a BUG (ie, in kernel mode, the right illegal instruction).
It then calls report_bug().  This searches __bug_table for a matching
instruction pointer, and if found, prints the corresponding file/line
information.  If report_bug() determines that it wasn't a BUG which caused the
trap, it returns BUG_TRAP_TYPE_NONE.

Some architectures (powerpc) implement WARN using the same mechanism; if the
illegal instruction was the result of a WARN, then report_bug(Q) returns
CONFIG_DEBUG_BUGVERBOSE; otherwise it returns BUG_TRAP_TYPE_BUG.

lib/bug.c keeps a list of loaded modules which can be searched for __bug_table
entries.  The architecture must call
module_bug_finalize()/module_bug_cleanup() from its corresponding
module_finalize/cleanup functions.

Unsetting CONFIG_DEBUG_BUGVERBOSE will reduce the kernel size by some amount.
At the very least, filename and line information will not be recorded for each
but, but architectures may decide to store no extra information per BUG at
all.

Unfortunately, gcc doesn't have a general way to mark an asm() as noreturn, so
architectures will generally have to include an infinite loop (or similar) in
the BUG code, so that gcc knows execution won't continue beyond that point.
gcc does have a __builtin_trap() operator which may be useful to achieve the
same effect, unfortunately it cannot be used to actually implement the BUG
itself, because there's no way to get the instruction's address for use in
generating the __bug_table entry.

[randy.dunlap@oracle.com: Handle BUG=n, GENERIC_BUG=n to prevent build errors]
[bunk@stusta.de: include/linux/bug.h must always #include <linux/module.h]
Signed-off-by: NJeremy Fitzhardinge <jeremy@goop.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Hugh Dickens <hugh@veritas.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      7664c5a1
  55. 08 12月, 2006 1 次提交
    • R
      [PATCH] lib functions: always build hweight for loadable modules · 702a28b1
      由 Randy Dunlap 提交于 
      Always build hweight8/16/32/64() functions into the kernel so that loadable
modules may use them.

I didn't remove GENERIC_HWEIGHT since ALPHA_EV67, ia64, and some variants
of UltraSparc(64) provide their own hweight functions.

Fixes config/build problems with NTFS=m and JOYSTICK_ANALOG=m.

  Kernel: arch/x86_64/boot/bzImage is ready  (#19)
    Building modules, stage 2.
    MODPOST 94 modules
  WARNING: "hweight32" [fs/ntfs/ntfs.ko] undefined!
  WARNING: "hweight16" [drivers/input/joystick/analog.ko] undefined!
  WARNING: "hweight8" [drivers/input/joystick/analog.ko] undefined!
  make[1]: *** [__modpost] Error 1
  make: *** [modules] Error 2
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      702a28b1
  57. 17 10月, 2006 2 次提交
  59. 12 10月, 2006 1 次提交