[PATCH] uml: network driver fixes

This is from Gerd Knorr.  It fixes a network hang caused by the host side of
an interface being full when the UML interface is brought up, preventing any
SIGIOs from happening.  It also implements an ioctl needed for ethtool.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/drivers/net_kern.c

@@ -19,6 +19,8 @@
 #include "linux/inetdevice.h"
 #include "linux/ctype.h"
 #include "linux/bootmem.h"
+#include "linux/ethtool.h"
+#include "asm/uaccess.h"
 #include "user_util.h"
 #include "kern_util.h"
 #include "net_kern.h"
@@ -127,6 +129,13 @@ static int uml_net_open(struct net_device *dev)
 	spin_lock(&opened_lock);
 	list_add(&lp->list, &opened);
 	spin_unlock(&opened_lock);
+
+	/* clear buffer - it can happen that the host side of the interface
+	 * is full when we get here.  In this case, new data is never queued,
+	 * SIGIOs never arrive, and the net never works.
+	 */
+	while((err = uml_net_rx(dev)) > 0) ;
+
  out:
 	spin_unlock(&lp->lock);
 	return(err);
@@ -240,7 +249,30 @@ static int uml_net_change_mtu(struct net_device *dev, int new_mtu)
 
 static int uml_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 {
-	return(-EINVAL);
+	static const struct ethtool_drvinfo info = {
+		.cmd     = ETHTOOL_GDRVINFO,
+		.driver  = "uml virtual ethernet",
+		.version = "42",
+	};
+	void *useraddr;
+	u32 ethcmd;
+
+	switch (cmd) {
+	case SIOCETHTOOL:
+		useraddr = ifr->ifr_data;
+		if (copy_from_user(&ethcmd, useraddr, sizeof(ethcmd)))
+			return -EFAULT;
+		switch (ethcmd) {
+		case ETHTOOL_GDRVINFO:
+			if (copy_to_user(useraddr, &info, sizeof(info)))
+				return -EFAULT;
+			return 0;
+		default:
+			return -EOPNOTSUPP;
+		}
+	default:
+		return -EINVAL;
+	}
 }
 
 void uml_net_user_timer_expire(unsigned long _conn)