1) Add non-blocking I/O on read

2) Add checks to make sure we do not dereference the softc when not found
because the device has been removed.

1 files changed, 32 insertions, 6 deletions

diff --git a/sys/dev/usb/ums.c b/sys/dev/usb/ums.c
index a97adb4..c8ec14e 100644
--- a/sys/dev/usb/ums.c
+++ b/sys/dev/usb/ums.c
@@ -397,6 +397,7 @@ ums_detach(device_t self)
 	 * the time the process gets a chance to notice. *_close and friends
 	 * should be fixed to handle this case.
 	 * Or we should do a delayed detach for this.
+	 * Does this delay now force tsleep to exit with an error?
 	 */
 
 #if 0
@@ -627,7 +628,7 @@ ums_close(dev_t dev, int flag, int fmt, struct proc *p)
 {
 	USB_GET_SC(ums, UMSUNIT(dev), sc);
 
-	if (sc == NULL)
+	if (!sc)
 		return 0;
 
 	if (sc->sc_enabled)
@@ -646,14 +647,18 @@ ums_read(dev_t dev, struct uio *uio, int flag)
 	int error;
 
 	s = splusb();
+	if (!sc) {
+		splx(s);
+		return EIO;
+	}
+
 	while (sc->qcount == 0 )  {
-		/* NWH XXX non blocking I/O ??
-		if (non blocking I/O ) {
+		if (flag & IO_NDELAY) {		/* non-blocking I/O */
 			splx(s);
 			return EWOULDBLOCK;
-		} else {
-		*/
-		sc->state |= UMS_ASLEEP;
+		}
+		
+		sc->state |= UMS_ASLEEP;	/* blocking I/O */
 		error = tsleep(sc, PZERO | PCATCH, "umsrea", 0);
 		if (error) {
 			splx(s);
@@ -662,8 +667,23 @@ ums_read(dev_t dev, struct uio *uio, int flag)
 			splx(s);
 			return EINTR;
 		}
+#if defined(__FreeBSD__)
+		/* check whether the device is still there */
+
+		sc = devclass_get_softc(ums_devclass, UMSUNIT(dev));
+		if (!sc) {
+			splx(s);
+			return EIO;
+		}
+#endif
 	}
 
+	/*
+	 * XXX we could optimise the use of splx/splusb somewhat. The writer
+	 * process only extends qcount and qtail. We could copy them and use the copies
+	 * to do the copying out of the queue.
+	 */
+
 	while ((sc->qcount > 0) && (uio->uio_resid > 0)) {
 		l = (sc->qcount < uio->uio_resid? sc->qcount:uio->uio_resid);
 		if (l > sizeof(buf))
@@ -694,6 +714,9 @@ ums_poll(dev_t dev, int events, struct proc *p)
 	int revents = 0;
 	int s;
 
+	if (!sc)
+		return 0;
+
 	s = splusb();
 	if (events & (POLLIN | POLLRDNORM)) {
 		if (sc->qcount) {
@@ -716,6 +739,9 @@ ums_ioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, struct proc *p)
 	int s;
 	mousemode_t mode;
 
+	if (!sc)
+		return EIO;
+
 	switch(cmd) {
 	case MOUSE_GETHWINFO:
 		*(mousehw_t *)addr = sc->hw;