linux/lib/Kconfig.debug, branch v2.6.26

debugobjects: add timer specific object debugging code

2008-04-30T15:29:53Z

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: Thomas Gleixner Acked-by: Ingo Molnar Cc: Greg KH Cc: Randy Dunlap Cc: Kay Sievers Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

infrastructure to debug (dynamic) objects

2008-04-30T15:29:53Z

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: Thomas Gleixner Signed-off-by: Ingo Molnar Cc: Greg KH Cc: Randy Dunlap Cc: Kay Sievers Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Add option to enable -Wframe-larger-than= on gcc 4.4

2008-04-25T18:23:47Z

Add option to enable -Wframe-larger-than= on gcc 4.4 gcc mainline (upcoming 4.4) added a new -Wframe-larger-than=... option to warn at build time about too large stack frames. Add a config option to enable this warning, since this very useful for the kernel. I choose (somewhat arbitarily) 2048 as default warning threshold for 64bit and 1024 as default for 32bit architectures. With some research and fixing all the code for smaller values these defaults should be probably lowered. With the default allyesconfigs have some new warnings, but I think that is all code that should be just fixed. At some point (when gcc 4.4 is released and widely used) this should obsolete make checkstack Signed-off-by: Andi Kleen Signed-off-by: Sam Ravnborg

[PATCH] r/o bind mounts: debugging for missed calls

2008-04-19T04:29:28Z

There have been a few oopses caused by 'struct file's with NULL f_vfsmnts. There was also a set of potentially missed mnt_want_write()s from dentry_open() calls. This patch provides a very simple debugging framework to catch these kinds of bugs. It will WARN_ON() them, but should stop us from having any oopses or mnt_writer count imbalances. I'm quite convinced that this is a good thing because it found bugs in the stuff I was working on as soon as I wrote it. [hch: made it conditional on a debug option. But it's still a little bit too ugly] [hch: merged forced remount r/o fix from Dave and akpm's fix for the fix] Signed-off-by: Dave Hansen Acked-by: Al Viro Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Al Viro

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6

2008-04-18T18:24:29Z

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6: (43 commits) firewire: cleanups firewire: fix synchronization of gap counts firewire: wait until PHY configuration packet was transmitted (fix bus reset loop) firewire: remove unused struct member firewire: use bitwise and to get reg in handle_registers firewire: replace more hex values with defined csr constants firewire: reread config ROM when device reset the bus firewire: replace static ROM cache by allocated cache firewire: fw-ohci: work around generation bug in TI controllers (fix AV/C and more) firewire: fw-ohci: extend logging of bus generations and node ID firewire: fw-ohci: conditionally log busReset interrupts firewire: fw-ohci: don't append to AT context when it's not active firewire: fw-ohci: log regAccessFail events firewire: fw-ohci: make sure HCControl register LPS bit is set firewire: fw-ohci: missing PPC PMac feature calls in failure path firewire: fw-ohci: untangle a mixed unsigned/signed expression firewire: debug interrupt events firewire: fw-ohci: catch self_id_count == 0 firewire: fw-ohci: add self ID error check firewire: fw-ohci: refactor probe, remove, suspend, resume ...

firewire: fw-ohci: add option for remote debugging

2008-04-18T15:55:33Z

This way firewire-ohci can be used for remote debugging like ohci1394. Version with amendment from Fri, 11 Apr 2008 00:08:08 +0200. Signed-off-by: Stefan Richter Acked-by: Bernhard Kaindl

Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-kgdb

2008-04-18T15:37:01Z

* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-kgdb: kgdb: always use icache flush for sw breakpoints kgdb: fix SMP NMI kgdb_handle_exception exit race kgdb: documentation fixes kgdb: allow static kgdbts boot configuration kgdb: add documentation kgdb: Kconfig fix kgdb: add kgdb internal test suite kgdb: fix several kgdb regressions kgdb: kgdboc pl011 I/O module kgdb: fix optional arch functions and probe_kernel_* kgdb: add x86 HW breakpoints kgdb: print breakpoint removed on exception kgdb: clocksource watchdog kgdb: fix NMI hangs kgdb: fix kgdboc dynamic module configuration kgdb: document parameters x86: kgdb support consoles: polling support, kgdboc kgdb: core uaccess: add probe_kernel_write()

Merge branch 'semaphore' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc

2008-04-18T15:25:29Z

* 'semaphore' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc: Remove DEBUG_SEMAPHORE from Kconfig Improve semaphore documentation Simplify semaphore implementation Add down_timeout and change ACPI to use it Introduce down_killable() Generic semaphore implementation Add semaphore.h to kernel_lock.c Fix quota.h includes

kgdb: core

2008-04-17T18:05:37Z

kgdb core code. Handles the protocol and the arch details. [ mingo@elte.hu: heavily modified, simplified and cleaned up. ] [ xemul@openvz.org: use find_task_by_pid_ns ] Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar Signed-off-by: Jan Kiszka Reviewed-by: Thomas Gleixner

Remove DEBUG_SEMAPHORE from Kconfig

2008-04-17T14:53:01Z

Alpha and FRV mutexes had an option to print lots of debugging messages in their semaphore implementation. This feature has not been carried over to the generic semaphores, so remove the stale Kconfig option. Signed-off-by: Matthew Wilcox