On Wed, 29 Oct 2008, Alan Stern wrote: > On Wed, 29 Oct 2008, Miklos Szeredi wrote: > > > Actually I was thinking of an rw-semaphore, not a mutex. But yeah > > that still has scalability problems. But it could be done with custom > > locking primitives, optimized for this case: > > > > suspend_disable(); > > /* driver stuff */ > > suspend_enable(); > > Yes, it could be done. And the overhead could be minimized by using > per-CPU variables. It would still be an awful lot of work, and easy to > get wrong. OK, getting back to this, as it seems to be the only way that we agree is doable. How about this, a) identify syscalls that may make drivers do I/O: - read - write - ioctl ??? b) add the suspend_disable/enable() primitives to these syscalls c) push primitives inside the implementation c) is slightly tricky, but could be done for example by setting a flag on open: FMODE_NO_SUSPEND_DISABLE (better name required), saying that implementation is responsible for getting the suspend disable magic right. For starters this flag could be set for all non-device opens (maybe all non-char-dev opens?), solving the fuse vs. freezer issues without any complicated trickery. Miklos _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
