On Mon, Oct 06, 2014 at 05:01:18PM -0400, Tejun Heo wrote: > Hello, > > On Mon, Oct 06, 2014 at 10:36:27PM +0200, Luis R. Rodriguez wrote: > > > Do we intend to keep this param permanently? Isn't this more of a > > > temp tool to be used during development? If so, maybe we should make > > > that clear with __DEVEL__ too? > > > > As its designed right now no, its not a temp tool, its there to > > require compatibility with old userspace. For modules we can require > > the module parameter but for built-in we need something else and this > > is what came to mind. It is also what would allow the prefer_async_probe > > flag too as otherwise we won't know if userspace is prepared. > > I don't get it. By prepared I meant that userspace can handle async probe, but you're right that we don't need to know that. I don't see how we'd be breaking old userspace by doing async probe of a driver is built-in right now... unless of course built-in always assumes all possible devices would be present after right before userspace init. > For in-kernel stuff, we already have a clear > synchronization point where we already synchronize all async calls. > Shouldn't we be flushing these async probes there too? This seems to be addressing if what I meant by prepared, "ready", so let me address this as I do think its important. By async calls do you mean users of async_schedule()? I see it also uses system_unbound_wq as well but I do not see anyone calling flush_workqueue(system_unbound_wq) on the kernel. We do use async_synchronize_full() on kernel_init() but that just waits. As it is we don't wait on init then, should we? Must we? Could / should we use bus.enable_kern_async=1 to enable avoiding having to wait ? At this point I'd prefer to address what we must do only. > insmod'ing is > userland visible but there's no reason this has to be for the built-in > drivers. Good point. bus.enable_kern_async=1 would still also serve as a helper for the driver core to figure out if it should use async probe then on modules if prefer_async_probe was enabled. Let me know if you figure out a way to avoid it. Luis -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
