> ---
> include/linux/slab.h | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> Index: linux-2.6/include/linux/slab.h
> ===================================================================
> --- linux-2.6.orig/include/linux/slab.h
> +++ linux-2.6/include/linux/slab.h
> @@ -23,6 +23,32 @@
> #define SLAB_CACHE_DMA 0x00004000UL /* Use GFP_DMA memory */
> #define SLAB_STORE_USER 0x00010000UL /* DEBUG: Store the last owner for bug hunting */
> #define SLAB_PANIC 0x00040000UL /* Panic if kmem_cache_create() fails */
> +/*
> + * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
> + *
> + * This delays freeing the SLAB page by a grace period, it does _NOT_
> + * delay object freeing. This means that if you do kmem_cache_free()
> + * that memory location is free to be reused at any time. Thus it may
> + * be possible to see another object there in the same RCU grace period.
> + *
> + * This feature only ensures the memory location backing the object
> + * stays valid, the trick to using this is relying on an independent
> + * object validation pass. Something like:
> + *
> + * rcu_read_lock()
> + * again:
> + * obj = lockless_lookup(key);
> + * if (obj) {
> + * if (!try_get_ref(obj)) // might fail for free objects
> + * goto again;
> + *
> + * if (obj->key != key) { // not the object we expected
> + * put_ref(obj);
> + * goto again;
> + * }
> + * }
> + * rcu_read_unlock();
> + */
> #define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */
> #define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */
> #define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */
>
> --
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