Locking and cleanup of tty netgraph node. Tty stack is Giant-locked,

so we need to acquire Giant in netgraph methods, so that we don't
race with line discipline methods. Remove NET_NEEDS_GIANT.

- Packets coming into node from netgraph are queued in ifqueue
  attached to node private data.
- Mutex in struct ifqueue is used to lock not only the queue, but
  the whole private data, and tp->t_lsc field.
- tp->t_lsc pointer is used to indicate whether line discipline is
  attached to netgraph or not.
- Use FLG_DIE flag to indicate that node may be destroyed.
  (This protection doesn't work, and it didn't before. Must be redesigned.)
- Increment ngt_unit atomically, removing mutex.
- Acquire Giant, when executing ngt_start() from netgraph context.
- Acquire Giant, when {,de}registering line discipline.
- Uncomment forcing queue mode on peers hook, since this is reasonable.
- Force queue mode on our hook, to avoid acquiring Giant when coming from
  network stack. We may already hold some mutexes at this point.

Cleanups:
- Use callout_pending() instead of our own flag.
- Remove spl(9) calls. Now we can use return() instead of ERROUT().

style(9):
- Sort includes.
- Sparse initializer for struct linesw.
- Remove some empty lines, sort declarations.

Reviewed by:	julian, phk
MFC after:	1 month

0 files changed, 0 insertions, 0 deletions