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.
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.
Invoking the ctor from within cache_alloc_debugcheck_after makes it
awkward for a dynamic checker of allocations and initializations.
Valgrind would be happier if allocation and initialization were
invoked at the same subroutine nesting level, such as in __cache_alloc:
cache_alloc_debugcheck_before(cachep, flags);
local_irq_save(save_flags);
objp = __do_cache_alloc(cachep, flags);
/* checker marks the space as allocated */
local_irq_restore(save_flags);
objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
if (objp && cachep->ctor)
cachep->ctor(objp, cachep, 0);
/* checker notes initializations during ctor [above] */
--
John Reiser, [EMAIL PROTECTED]
--
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/
