Amit Shah <amit.shah@xxxxxxxxxx> writes: > On (Mon) 22 Jul 2013 [15:26:22], Rusty Russell wrote: >> Amit Shah <amit.shah@xxxxxxxxxx> writes: >> > The removal functions act on the vqs, and the vq operations need to be >> > locked. >> > >> > Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx> >> >> How can userspace access the port now? By the time we are cleaning up >> buffers, there should be no possibility of such accesses. > > close(), can happen when the port is being unplugged. We're just > making sure here that port_fops_release() and unplug_port() don't try > to free up the same data at the same time. Why doesn't reference counting help us here? Surely the last one should clean up? >> The number of bugfixes here is deeply disturbing. > > Yes, the first three fix a bug - close() after unplug. However, the > others are inadequate locking fixes which I noticed while fixing that > bug. > > Port unplug isn't a frequently-used or tested path, so these were > lying unnoticed so far. > >> I wonder if it's be >> easier to rewrite it all with a lock per port, and one global to protect >> ports_driver_data. > > Hm, with this series, I don't see anything that might need extra > locking. Though I'll take a look at this afresh in a while -- and see > if we could simplify something. > > Given that this was necessary only for unplug operations, (and they > aren't a 'regular operation', so we could drop the stable@ for the > series?), are you OK with this series for now? Let's skip stable@ for theoretical bugs. Please repost. Cheers, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
