While emulating the bell, wsdisplay could end up sleeping when reaching

down to wsmux. This does not work since we're in interrupt context, as
pointed out by witness.

Instead, defer the work to a task which in turn will execute in process
context.

Problem reported by beck@

ok visa@

diff --git a/sys/dev/wscons/wsdisplay.c b/sys/dev/wscons/wsdisplay.c
index cc6f100..15e54fa 100644 (file)
--- a/sys/dev/wscons/wsdisplay.c
+++ b/sys/dev/wscons/wsdisplay.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: wsdisplay.c,v 1.149 2022/07/15 17:57:27 kettenis Exp $ */
+/* $OpenBSD: wsdisplay.c,v 1.150 2022/11/26 06:20:18 anton Exp $ */
 /* $NetBSD: wsdisplay.c,v 1.82 2005/02/27 00:27:52 perry Exp $ */
 
 /*
@@ -39,6 +39,7 @@
 #include <sys/malloc.h>
 #include <sys/syslog.h>
 #include <sys/systm.h>
+#include <sys/task.h>
 #include <sys/tty.h>
 #include <sys/signalvar.h>
 #include <sys/errno.h>
@@ -83,6 +84,8 @@ struct wsscreen_internal {
 struct wsscreen {
        struct wsscreen_internal *scr_dconf;
 
+       struct task     scr_emulbell_task;
+
        struct tty *scr_tty;
        int     scr_hold_screen;                /* hold tty output */
 
@@ -165,6 +168,8 @@ struct wsdisplay_softc {
        int sc_focusidx;        /* available only if sc_focus isn't null */
        struct wsscreen *sc_focus;
 
+       struct taskq *sc_taskq;
+
 #ifdef HAVE_BURNER_SUPPORT
        struct timeout sc_burner;
        int     sc_burnoutintvl;        /* delay before blanking (ms) */
@@ -204,6 +209,8 @@ int wsdisplay_emul_detach(struct device *, int);
 
 int    wsdisplay_activate(struct device *, int);
 
+void   wsdisplay_emulbell_task(void *);
+
 struct cfdriver wsdisplay_cd = {
        NULL, "wsdisplay", DV_TTY
 };
@@ -304,6 +311,7 @@ wsscreen_attach(struct wsdisplay_softc *sc, int console, const char *emul,
                dconf->scrdata = type;
        }
 
+       task_set(&scr->scr_emulbell_task, wsdisplay_emulbell_task, scr);
        scr->scr_dconf = dconf;
        scr->scr_tty = ttymalloc(0);
        scr->sc = sc;
@@ -327,6 +335,7 @@ wsscreen_detach(struct wsscreen *scr)
        }
        (*scr->scr_dconf->wsemul->detach)(scr->scr_dconf->wsemulcookie,
            &ccol, &crow);
+       taskq_del_barrier(scr->sc->sc_taskq, &scr->scr_emulbell_task);
        free(scr->scr_dconf, M_DEVBUF, sizeof(*scr->scr_dconf));
        free(scr, M_DEVBUF, sizeof(*scr));
 }
@@ -653,6 +662,8 @@ wsdisplay_common_detach(struct wsdisplay_softc *sc, int flags)
        }
 #endif
 
+       taskq_destroy(sc->sc_taskq);
+
        return (0);
 }
 
@@ -721,6 +732,8 @@ wsdisplay_common_attach(struct wsdisplay_softc *sc, int console, int kbdmux,
        sc->sc_isconsole = console;
        sc->sc_resumescreen = WSDISPLAY_NULLSCREEN;
 
+       sc->sc_taskq = taskq_create(sc->sc_dv.dv_xname, 1, IPL_TTY, 0);
+
        if (console) {
                KASSERT(wsdisplay_console_initted);
                KASSERT(wsdisplay_console_device == NULL);
@@ -1588,7 +1601,15 @@ wsdisplay_emulbell(void *v)
        if (scr->scr_flags & SCR_GRAPHICS) /* can this happen? */
                return;
 
-       (void) wsdisplay_internal_ioctl(scr->sc, scr, WSKBDIO_BELL, NULL,
+       task_add(scr->sc->sc_taskq, &scr->scr_emulbell_task);
+}
+
+void
+wsdisplay_emulbell_task(void *v)
+{
+       struct wsscreen *scr = v;
+
+       (void)wsdisplay_internal_ioctl(scr->sc, scr, WSKBDIO_BELL, NULL,
            FWRITE, NULL);
 }