Hi John, On Dec 17, 2007 5:47 PM, John Reiser <[EMAIL PROTECTED]> wrote: > In mm/slab.c, the DEBUG variant of cache_alloc_debugcheck_after > might call cachep->ctor(objp, cachep, 0); but the non-DEBUG > variant does absolutely nothing. idr_pre_get is a routine > which notices the difference.
How does ipr_pre_get notice this? On Dec 17, 2007 5:47 PM, John Reiser <[EMAIL PROTECTED]> wrote: > Even when cache_alloc_debugcheck_after does invoke the ctor, > then it is conditional upon cachep->flags & SLAB_POISON. This > assumes that the only two states are poisoned and all-zero > (from .bss static, or via a cleared new page frame.) > So if SLAB_POISON is not specified, then a ctor which > does anything other than memset(,0,) is out of luck. > Instead: if a ctor is specified then it should be called > for each successful allocation. Sorry, I don't understand at all what's the problem is here. For the common (non-poison) case, we initialize all objects *once* whenever a cache is grown (see cache_grow calling cache_init_objs) which is the whole point of having constructors. When poisoning is enabled, we obviously cannot do this which is why we call the constructor for every allocation. Pekka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/