On Thu, 24 Mar 2005, Patrick Mochel wrote: > > On Thu, 24 Mar 2005, Alan Stern wrote: > > > On Wed, 23 Mar 2005, Patrick Mochel wrote: > > > > It would make it potentially very hard to debug and add a lot of > > > time to the process. > > > > Hard to debug, maybe... we can't tell without actually trying. Adding a > > lot of time to the suspend process, no. Acquiring the locks would block > > only for things that should cause you to block anyway, like trying to > > suspend a device while it's being probed. > > It would change the locking from an O(1) operation to an O(n) operation, > where n is the number of devices. Taking any lock is not cheap, so taking > N locks, when is N is large is going to be grossly inefficient. Ok, I'm a hypocrit. :) The first patch in the series that I posted adds a semaphore to struct device that is taken before each driver operation, including suspend and resume. It is dropped, though, when the operation is complete. I think that's the right way to do it, and I'm interested to hear if that will work for what you guys want to do. I *do* realize that it is equivalent in terms of time spent acquiring and releasing locks that I bashed above. I will eat my words now. Thanks, Pat
