* Pekka Enberg ([EMAIL PROTECTED]) wrote: > Hi Mathieu, > > On Feb 19, 2008 4:02 PM, Mathieu Desnoyers <[EMAIL PROTECTED]> wrote: > > - stat(c, ALLOC_FASTPATH); seems to be using a var++, therefore > > indicating it is not reentrant if IRQs are disabled. Since those are > > only stats, I guess it's ok, but still weird. > > What is not re-entrant? >
incrementing the variable with a "++" when interrupts are not disabled. It's not an atomic add and it's racy. The code within stat() does exactly this. > On Feb 19, 2008 4:02 PM, Mathieu Desnoyers <[EMAIL PROTECTED]> wrote: > > Since this shows mostly with network card drivers, I think the most > > plausible cause would be an IRQ nesting over kmem_cache_alloc_node and > > calling it. > > Yes, this can happen. Are you saying it is not safe to be in the > lockless path when an IRQ triggers? It should be safe, but I think Eric pointed the correct problem in his reply. Thanks, Mathieu -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- 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/
