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, 20 insertions, 3 deletions

diff --git a/sys/dev/syscons/scvidctl.c b/sys/dev/syscons/scvidctl.c
index b28752b..9e142d0 100644
--- a/sys/dev/syscons/scvidctl.c
+++ b/sys/dev/syscons/scvidctl.c
@@ -36,6 +36,11 @@
 #include <sys/kernel.h>
 #include <sys/fbio.h>
 #include <sys/consio.h>
+#include <sys/filedesc.h>
+#include <sys/lock.h>
+#include <sys/sx.h>
+#include <sys/mutex.h>
+#include <sys/proc.h>
 
 #include <dev/fb/fbreg.h>
 #include <dev/syscons/syscons.h>
@@ -228,7 +233,11 @@ sc_set_text_mode(scr_stat *scp, struct tty *tp, int mode, int xsize, int ysize,
 	|| tp->t_winsize.ws_row != scp->ysize) {
 	tp->t_winsize.ws_col = scp->xsize;
 	tp->t_winsize.ws_row = scp->ysize;
-	pgsignal(tp->t_pgrp, SIGWINCH, 1);
+	if (tp->t_pgrp != NULL) {
+	    PGRP_LOCK(tp->t_pgrp);
+	    pgsignal(tp->t_pgrp, SIGWINCH, 1);
+	    PGRP_UNLOCK(tp->t_pgrp);
+	}
     }
 
     return 0;
@@ -291,7 +300,11 @@ sc_set_graphics_mode(scr_stat *scp, struct tty *tp, int mode)
 	|| tp->t_winsize.ws_ypixel != scp->ypixel) {
 	tp->t_winsize.ws_xpixel = scp->xpixel;
 	tp->t_winsize.ws_ypixel = scp->ypixel;
-	pgsignal(tp->t_pgrp, SIGWINCH, 1);
+	if (tp->t_pgrp != NULL) {
+	    PGRP_LOCK(tp->t_pgrp);
+	    pgsignal(tp->t_pgrp, SIGWINCH, 1);
+	    PGRP_UNLOCK(tp->t_pgrp);
+	}
     }
 
     return 0;
@@ -423,7 +436,11 @@ sc_set_pixel_mode(scr_stat *scp, struct tty *tp, int xsize, int ysize,
 	|| tp->t_winsize.ws_row != scp->ysize) {
 	tp->t_winsize.ws_col = scp->xsize;
 	tp->t_winsize.ws_row = scp->ysize;
-	pgsignal(tp->t_pgrp, SIGWINCH, 1);
+	if (tp->t_pgrp != NULL) {
+	    PGRP_LOCK(tp->t_pgrp);
+	    pgsignal(tp->t_pgrp, SIGWINCH, 1);
+	    PGRP_UNLOCK(tp->t_pgrp);
+	}
     }
 
     return 0;