X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fum%2Fdrivers%2Fnet_user.c;h=0a7786e00cfb80da658f6474f562eca1b9d5c067;hb=43bc926fffd92024b46cafaf7350d669ba9ca884;hp=3730d4f1271368e43ee147303973b8490ab153ea;hpb=cee37fe97739d85991964371c1f3a745c00dd236;p=linux-2.6.git

diff --git a/arch/um/drivers/net_user.c b/arch/um/drivers/net_user.c
index 3730d4f12..0a7786e00 100644
--- a/arch/um/drivers/net_user.c
+++ b/arch/um/drivers/net_user.c
@@ -16,7 +16,6 @@
 #include "user_util.h"
 #include "kern_util.h"
 #include "net_user.h"
-#include "helper.h"
 #include "os.h"
 
 int tap_open_common(void *dev, char *gate_addr)
@@ -48,10 +47,12 @@ void tap_check_ips(char *gate_addr, unsigned char *eth_addr)
 	}
 }
 
+/* Do reliable error handling as this fails frequently enough. */
 void read_output(int fd, char *output, int len)
 {
-	int remain, n, actual;
+	int remain, ret, expected;
 	char c;
+	char *str;
 
 	if(output == NULL){
 		output = &c;
@@ -59,23 +60,31 @@ void read_output(int fd, char *output, int len)
 	}
 		
 	*output = '\0';
-	n = os_read_file(fd, &remain, sizeof(remain));
-	if(n != sizeof(remain)){
-		printk("read_output - read of length failed, err = %d\n", -n);
-		return;
+	ret = os_read_file(fd, &remain, sizeof(remain));
+
+	if (ret != sizeof(remain)) {
+		expected = sizeof(remain);
+		str = "length";
+		goto err;
 	}
 
 	while(remain != 0){
-		n = (remain < len) ? remain : len;
-		actual = os_read_file(fd, output, n);
-		if(actual != n){
-			printk("read_output - read of data failed, "
-			       "err = %d\n", -actual);
-			return;
+		expected = (remain < len) ? remain : len;
+		ret = os_read_file(fd, output, expected);
+		if (ret != expected) {
+			str = "data";
+			goto err;
 		}
-		remain -= actual;
+		remain -= ret;
 	}
+
 	return;
+
+err:
+	if (ret < 0)
+		printk("read_output - read of %s failed, errno = %d\n", str, -ret);
+	else
+		printk("read_output - read of %s failed, read only %d of %d bytes\n", str, ret, expected);
 }
 
 int net_read(int fd, void *buf, int len)
@@ -173,7 +182,9 @@ static int change_tramp(char **argv, char *output, int output_len)
 	pe_data.stdout = fds[1];
 	pid = run_helper(change_pre_exec, &pe_data, argv, NULL);
 
-	read_output(fds[0], output, output_len);
+	if (pid > 0)	/* Avoid hang as we won't get data in failure case. */
+		read_output(fds[0], output, output_len);
+
 	os_close_file(fds[0]);
 	os_close_file(fds[1]);