> I have a couple questions. > Is there some friendly documentation on memory locking and DMA to > userspace in 2.4 somewhere (besides the source code)? No (I don't know any). > What if a malicious or buggy program free()s the buffers while the > driver still has them? Can it crash the system? If the driver takes care (i.e. check return values etc) it will not crash. If you try to create/lock kiobuf's for a invalid userspace pointer you should get back -EINVAL, -EFAULT or something like that. Catch that, and you are fine. The lock will pin down the physical pages in memory. They will stay even if the application free's them while they are locked. So the DMA transfer can complete, the driver will unlock them, then they will be freed. Gerd -- Get back there in front of the computer NOW. Christmas can wait. -- Linus "the Grinch" Torvalds, 24 Dec 2000 on linux-kernel
