This conversion is unfortunate in the sense that Unix local domain sockets are relatively lightweight. LocalHost UDP sockets are much heavier weight since they rely on the full UDP stack. If anyone is up for a complete redesign, then using some shared memory and a POSIX message queue would be lightweight again.
This commit also fixes several bugs that were not testable before the inode tree deadlock. I cannot say that the logic is 100% stable but it does not have basic functionality.
Squashed commit of the following:
fs/userfs: Order locking so that access to the shared I/O buffer is also locked.
fs/userfs: Converts to use LocalHost UDP loopback for IPC.
As a policy, all internal OS implementations must use "detached" files which are valid in any context and do not depend on the validity of a file descriptor at any point in time. This commit converts the usage of file descriptors to detached files throughout the local socket implementation.
Squashed commit of the following:
net/local: Finish change to eliminate use of file descriptors.
net/local: A little more of the conversion.
net/local: Beginning of chnages to eliminate use of file descriptors in the local socket implementeation. poll() will be a problem.
