Module Name: src
Committed By: jmcneill
Date: Sun Jan 17 16:51:12 UTC 2021
Modified Files:
src/sys/dev/wscons: wsdisplay_vcons.c
Log Message:
The change from config_interrupts to a kthread for VCONS_DRAW_INTR init
unfortunately makes it easier to trigger a race that results in characters
not being erased properly at boot. Work around the original issue a
different way by creating a fake device_t and defer initialization until
we are sure that config_interrupt threads are done. This is not ideal and
the race is still present but fixing this properly would require a rewrite
to make this code MP-safe.
To generate a diff of this commit:
cvs rdiff -u -r1.45 -r1.46 src/sys/dev/wscons/wsdisplay_vcons.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/wscons/wsdisplay_vcons.c
diff -u src/sys/dev/wscons/wsdisplay_vcons.c:1.45 src/sys/dev/wscons/wsdisplay_vcons.c:1.46
--- src/sys/dev/wscons/wsdisplay_vcons.c:1.45 Sat Jan 2 03:00:56 2021
+++ src/sys/dev/wscons/wsdisplay_vcons.c Sun Jan 17 16:51:12 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: wsdisplay_vcons.c,v 1.45 2021/01/02 03:00:56 macallan Exp $ */
+/* $NetBSD: wsdisplay_vcons.c,v 1.46 2021/01/17 16:51:12 jmcneill Exp $ */
/*-
* Copyright (c) 2005, 2006 Michael Lorenz
@@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: wsdisplay_vcons.c,v 1.45 2021/01/02 03:00:56 macallan Exp $");
+__KERNEL_RCSID(0, "$NetBSD: wsdisplay_vcons.c,v 1.46 2021/01/17 16:51:12 jmcneill Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -121,7 +121,7 @@ static void vcons_unlock(struct vcons_sc
#ifdef VCONS_DRAW_INTR
static void vcons_intr(void *);
static void vcons_softintr(void *);
-static void vcons_init_thread(void *);
+static int vcons_intr_enable(device_t);
#endif
int
@@ -180,11 +180,16 @@ vcons_init(struct vcons_data *vd, void *
callout_setfunc(&vd->intr, vcons_intr, vd);
vd->intr_valid = 1;
- if (kthread_create(PRI_NONE, 0, NULL, vcons_init_thread, vd, NULL,
- "vcons_init") != 0) {
- printf("%s: unable to create thread.\n", __func__);
- return -1;
- }
+ /*
+ * Defer intr drawing until after autoconfiguration has completed
+ * to serialize device attachment messages w/ the initial screen
+ * redraw as a workaround for the lack of MP-safeness in this
+ * subsystem. To register with autoconf, we need to create a fake
+ * device_t and pass that in as a handle to config_interrupts.
+ */
+ snprintf(vd->fake_dev.dv_xname, sizeof(vd->fake_dev.dv_xname), "vcons");
+ vd->fake_dev.dv_private = vd;
+ config_finalize_register(&vd->fake_dev, vcons_intr_enable);
#endif
return 0;
}
@@ -1493,14 +1498,15 @@ vcons_softintr(void *cookie)
callout_schedule(&vd->intr, mstohz(33));
}
-static void
-vcons_init_thread(void *cookie)
+static int
+vcons_intr_enable(device_t fake_dev)
{
- struct vcons_data *vd = (struct vcons_data *)cookie;
+ struct vcons_data *vd = device_private(fake_dev);
vd->use_intr = 2;
callout_schedule(&vd->intr, mstohz(33));
- kthread_exit(0);
+
+ return 0;
}
#endif /* VCONS_DRAW_INTR */
