On Fri, 2011-11-04 at 13:53 +0800, Rakib Mullick wrote: > On Thu, Nov 3, 2011 at 11:40 PM, Srivatsa S. Bhat > <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> wrote: > > Hi, > > > > On 11/03/2011 05:32 PM, Lin Ming wrote: > >> On Thu, 2011-11-03 at 18:48 +0800, Rakib Mullick wrote: > >>> Calling pm-suspend might trigger a recursive lock in it's code path. In function acpi_hw_clear_acpi_status, > >> > >> As I replied at https://lkml.org/lkml/2011/9/22/6, I still don't think > >> there is a recursive lock. > >> > > > > At first look, it definitely doesn't look like a recursive lock, as Lin said. > > But, quoting Documentation/lockdep-design.txt: > > > > "Multi-lock dependency rules: > > ---------------------------- > > > > The same lock-class must not be acquired twice, because this could lead > > to lock recursion deadlocks." > > > > So, Rakib, do the 2 locks belong to the same lock-class? If yes, then I think > > that is the reason for the lockdep splat. Could you show the lockdep warning? > > > Yes, same lock-class. And as per "Multi-lock dependency rules:", it > leads to lock recursion deadlocks. > Lockdep warning attached. > > > By the way, another way to look at this patch is as an optimization.. > > i.e., if acpi_gbl_hardware_lock doesn't need to be held to call > > acpi_ev_walk_gpe_list(), then we can move from the coarse-grained locking > > to finer-grained locking by releasing it earlier, as you did in your patch. > > [Note that you will have to update the goto label also, i.e., rename it as > > 'exit' or something like that] > > > I can do it, thanks for suggestions. But, what does Lin thinks? Lin > are you okay? I'm OK. We need to figure out why the dead lock happens. Could you also paste the patch which trigger this dead lock? Thanks, Lin Ming > > Thanks, > Rakib -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
