From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Fri, 9 Jan 2009 21:51:56 +0000 (-0800)
Subject: Fix a system livelock when ^C'ing a program sleeping in the console
X-Git-Tag: v2.3.0~60^2~3
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/f3628b8631c318c4df61b8ead7e60eb632a22a01

Fix a system livelock when ^C'ing a program sleeping in the console
driver.  ERESTART must be propagated back to userland so the signal can
be processed.  Trying to loop on it livelocks the machine.

Reported-by: Hasso Tepper
---

diff --git a/sys/dev/misc/syscons/syscons.c b/sys/dev/misc/syscons/syscons.c
index 36b6c477ab..59ec308c61 100644
--- a/sys/dev/misc/syscons/syscons.c
+++ b/sys/dev/misc/syscons/syscons.c
@@ -987,8 +987,8 @@ scioctl(struct dev_ioctl_args *ap)
 	scp = SC_STAT(SC_DEV(sc, i));
 	if (scp == scp->sc->cur_scp)
 	    return 0;
-	while ((error=tsleep((caddr_t)&scp->smode, PCATCH,
-			     "waitvt", 0)) == ERESTART) ;
+	error = tsleep((caddr_t)&scp->smode, PCATCH, "waitvt", 0);
+	/* May return ERESTART */
 	return error;
 
     case VT_GETACTIVE:		/* get active vty # */
@@ -2021,8 +2021,9 @@ wait_scrn_saver_stop(sc_softc_t *sc)
 	    break;
 	}
 	error = tsleep((caddr_t)&scrn_blanked, PCATCH, "scrsav", 0);
-	if ((error != 0) && (error != ERESTART))
-	    break;
+	/* May return ERESTART */
+	if (error)
+		break;
     }
     run_scrn_saver = FALSE;
     return error;