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SubjectRe: [patch 2/5] infrastructure to debug (dynamic) objects
On Fri, 21 Mar 2008 20:26:18 -0000 Thomas Gleixner wrote:

> Documentation/kernel-parameters.txt | 2
> include/linux/debugobjects.h | 90 +++
> init/main.c | 3
> lib/Kconfig.debug | 23
> lib/Makefile | 1
> lib/debugobjects.c | 890 ++++++++++++++++++++++++++++++++++++
> mm/page_alloc.c | 10
> mm/slab.c | 10
> mm/slub.c | 3
> mm/vmalloc.c | 2
> 10 files changed, 1030 insertions(+), 4 deletions(-)
>
> Index: linux-2.6/lib/Kconfig.debug
> ===================================================================
> --- linux-2.6.orig/lib/Kconfig.debug
> +++ linux-2.6/lib/Kconfig.debug
> @@ -183,6 +183,29 @@ config TIMER_STATS
> (it defaults to deactivated on bootup and will only be activated
> if some application like powertop activates it explicitly).
>
> +config DEBUG_OBJECTS
> + bool "Debug object operations"
> + depends on DEBUG_KERNEL
> + help
> + If you say Y here, additional code will be inserted into the
> + kernel to track the life time of various objects and validate

lifetime

> + the operations on those objects.
> +
> +config DEBUG_OBJECTS_SELFTEST
> + bool "Debug objects selftest"
> + depends on DEBUG_OBJECTS
> + help
> + This enables the selftest of the object debug code.
> +
> +config DEBUG_OBJECTS_FREE
> + bool "Debug objects in freed memory"
> + depends on DEBUG_OBJECTS
> + help
> + This enables checks whether a k/v free operation frees an area

Please say "kfree/vfree" so that we (I, others) don't have to think
"what the heck is a k/v free operation?".

> + which contains an object which has not been deactivated
> + properly. This can make kmalloc/kfree-intensive workloads
> + much slower.
> +
> config DEBUG_SLAB
> bool "Debug slab memory allocations"
> depends on DEBUG_KERNEL && SLAB

> Index: linux-2.6/lib/debugobjects.c
> ===================================================================
> --- /dev/null
> +++ linux-2.6/lib/debugobjects.c
> @@ -0,0 +1,890 @@
...

> +/*
> + * We run out of memory. That means we probably have tons of objects

ran

> + * allocated.
> + */
> +static void debug_objects_oom(void)
> +{
> + struct debug_bucket *db = obj_hash;
> + struct hlist_node *node, *tmp;
> + struct debug_obj *obj;
> + unsigned long flags;
> + int i;
> +
> + printk(KERN_WARNING "ODEBUG: Out of memory. ODEBUG disabled\n");
> +
> + for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
> + spin_lock_irqsave(&db->lock, flags);
> + hlist_for_each_entry_safe(obj, node, tmp, &db->list, node) {
> + hlist_del(&obj->node);
> + free_object(obj);
> + }
> + spin_unlock_irqrestore(&db->lock, flags);
> + }
> +}

> +/**
> + * debug_object_init_on_stack - debug checks when an object on stack is
> + * initialized

Unfortunately the first line of kernel-doc notation ("short description")
is limited to one line. Even if it exceeds 80 columns. :(

> + * @addr: address of the object
> + * @descr: pointer to an object specific debug description structure
> + */
> +void debug_object_init_on_stack(void *addr, struct debug_obj_descr *descr)
> +{
> + if (!debug_objects_enabled)
> + return;
> +
> + __debug_object_init(addr, descr, 1);
> +}


---
~Randy

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