Lock struct pgrp, session and sigio.

New locks are:

- pgrpsess_lock which locks the whole pgrps and sessions,
- pg_mtx which protects the pgrp members, and
- s_mtx which protects the session members.

Please refer to sys/proc.h for the coverage of these locks.

Changes on the pgrp/session interface:

- pgfind() needs the pgrpsess_lock held.

- The caller of enterpgrp() is responsible to allocate a new pgrp and
  session.

- Call enterthispgrp() in order to enter an existing pgrp.

- pgsignal() requires a pgrp lock held.

Reviewed by:	jhb, alfred
Tested on:	cvsup.jp.FreeBSD.org
		(which is a quad-CPU machine running -current)

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 6b698e470413..6de34efa2a03 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -305,12 +305,14 @@ proc0_init(void *dummy __unused)
 	 */
 	LIST_INSERT_HEAD(&allproc, p, p_list);
 	LIST_INSERT_HEAD(PIDHASH(0), p, p_hash);
+	mtx_init(&pgrp0.pg_mtx, "process group", MTX_DEF);
 	p->p_pgrp = &pgrp0;
 	LIST_INSERT_HEAD(PGRPHASH(0), &pgrp0, pg_hash);
 	LIST_INIT(&pgrp0.pg_members);
 	LIST_INSERT_HEAD(&pgrp0.pg_members, p, p_pglist);
 
 	pgrp0.pg_session = &session0;
+	mtx_init(&session0.s_mtx, "session", MTX_DEF);
 	session0.s_count = 1;
 	session0.s_leader = p;