umstc_intr is not in process context when adjusting wscons brightness. When brightness

is pushed to 0, the backlight is disabled by some backend code which happens to sleep.
Solve this by bouncing to process context via a task.
ok kettenis

1 files changed, 31 insertions, 4 deletions

diff --git a/sys/dev/usb/umstc.c b/sys/dev/usb/umstc.c
index bb992757a03..71cd2d2b829 100644
--- a/sys/dev/usb/umstc.c
+++ b/sys/dev/usb/umstc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: umstc.c,v 1.2 2020/08/23 11:08:02 mglocker Exp $ */
+/*	$OpenBSD: umstc.c,v 1.3 2020/09/14 15:21:08 deraadt Exp $ */
 
 /*
  * Copyright (c) 2020 joshua stein <jcs@jcs.org>
@@ -26,6 +26,8 @@
 #include <sys/systm.h>
 #include <sys/kernel.h>
 #include <sys/device.h>
+#include <sys/atomic.h>
+#include <sys/task.h>
 
 #include <dev/usb/usb.h>
 #include <dev/usb/usbhid.h>
@@ -41,13 +43,16 @@
 #include "wsdisplay.h"
 
 struct umstc_softc {
-	struct uhidev sc_hdev;
+	struct uhidev	sc_hdev;
+	struct task	sc_brightness_task;
+	int		sc_brightness_steps;
 };
 
 void	umstc_intr(struct uhidev *addr, void *ibuf, u_int len);
 int	umstc_match(struct device *, void *, void *);
 void	umstc_attach(struct device *, struct device *, void *);
 int	umstc_detach(struct device *, int flags);
+void	umstc_brightness_task(void *);
 
 extern int wskbd_set_mixervolume(long, long);
 
@@ -110,6 +115,8 @@ umstc_attach(struct device *parent, struct device *self, void *aux)
 
 	uhidev_open(&sc->sc_hdev);
 
+	task_set(&sc->sc_brightness_task, umstc_brightness_task, sc);
+
 	printf("\n");
 }
 
@@ -118,6 +125,8 @@ umstc_detach(struct device *self, int flags)
 {
 	struct umstc_softc *sc = (struct umstc_softc *)self;
 
+	task_del(systq, &sc->sc_brightness_task);
+
 	uhidev_close(&sc->sc_hdev);
 
 	return 0;
@@ -156,12 +165,14 @@ umstc_intr(struct uhidev *addr, void *buf, u_int len)
 		break;
 	case 0x70: /* brightness down */
 #if NWSDISPLAY > 0
-		wsdisplay_brightness_step(NULL, -1);
+		atomic_sub_int(&sc->sc_brightness_steps, 1);
+		task_add(systq, &sc->sc_brightness_task);
 #endif
 		break;
 	case 0x6f: /* brightness up */
 #if NWSDISPLAY > 0
-		wsdisplay_brightness_step(NULL, 1);
+		atomic_add_int(&sc->sc_brightness_steps, 1);
+		task_add(systq, &sc->sc_brightness_task);
 #endif
 		break;
 	case 0:
@@ -173,3 +184,19 @@ umstc_intr(struct uhidev *addr, void *buf, u_int len)
 		printf("\n");
 	}
 }
+
+void
+umstc_brightness_task(void *arg)
+{
+	struct umstc_softc *sc = arg;
+	int steps = atomic_swap_uint(&sc->sc_brightness_steps, 0);
+	int dir = 1;
+
+	if (steps < 0) {
+		steps = -steps;
+		dir = -1;
+	}
+	
+	while (steps--)
+		wsdisplay_brightness_step(NULL, dir);
+}