Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > But I know - we *have* one of those. There's already a system call for > it, and has been forever. One that we then extended to allow people to > change the buffer size, and do a lot of other things with. > > It's called "pipe()". And you can give the writing side to other user > space processes too, in case you are running an older kernel that > didn't have some "event pipe support". It comes with resource > management, because people already use those things. Can you write into a pipe from softirq context and/or with spinlocks held and/or with the RCU read lock held? That is a requirement. Another is that messages get inserted whole or not at all (or if they are truncated, the size field gets updated). Since one end would certainly be attached to an fd, it looks on the face of it that writing into the pipe would require taking pipe->mutex. David
