we no longer need to guard against access from hardware interrupt handlers.
Additionally, if cloning a process with CLONE_SIGHAND, arrange to have the
child process share the parent's lock so that signal state may be kept in
sync. Partially addresses PR kern/37437.
- Redo reference counting to be sane. LWPs accessing files take a short
term reference on the local file descriptor. This is the most common
case. While a file is in a process descriptor table, a reference is
held to the file. The file reference count only changes during control
operations like open() or close(). Code that comes at files from an
unusual direction (i.e. foreign to the process) like procfs or sysctl
takes a reference on the file (f_count), and not on a descriptor.
- Remove knowledge of reference counting and locking from most code that
deals with files.
- Make the usual case of file descriptor lookup lockless.
- Make kqueue MP and MT safe. PR kern/38098, PR kern/38137.
- Fix numerous file handling bugs, and bugs in the descriptor code that
affected multithreaded processes.
- Split descriptor system calls out into sys_descrip.c.
- A few stylistic changes: KNF, remove unused casts now that caddr_t is
gone. Replace dumb gotos with loop control in a few places.
- Don't do redundant pointer passing (struct proc, lwp, filedesc *) unless
the routine is likely to be inlined. Most of the time it's about the
current process.
rmind