On Friday, 6 July 2007 00:59, Benjamin Herrenschmidt wrote: > On Thu, 2007-07-05 at 10:23 -0400, Alan Stern wrote: > > > > How will that help? Block the kernel thread in the freezer or block it > > in the driver -- either way it is blocked. So how do your deadlocks > > get resolved? > > Because nobody is waiting on that kernel thread anyway without a freezer > so there is no deadlock anymore. I'm not sure what you mean. The freezer doesn't wait for threads that are already frozen ... > > I disagree with your analysis -- not that it's completely wrong, but it > > points out an existing basic problem in the kernel. The kernel should > > never depend on userspace! More correctly, a task executing in the > > kernel should never block with any sort of mutex or other lock held (in > > a way that would preclude it from being frozen, let's say) while > > waiting for a response from userspace. > > > > Then the dependency graph would be easy to construct: User tasks can > > depend on whatever they want, and kernel threads never depend on a user > > task. > > In an idea world, there would be no hunger... > > > If this contradicts the existing implementations and APIs for userspace > > filesystems, then so be it. My conclusion would be that the > > implementations and APIs should be changed. > > Why are you guys working so hard and spending so much energy to try to > avoid doing the right thing is beyond my understanding... > > > It _does_ apply to kernel threads. That's exactly why I wrote above > > that kernel threads which try to do I/O during a suspend will need > > extra attention. > > Ok none at all if you don't have a freezer. Provided that drivers can handle that. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
