[PATCH] uml: error handling fixes

Blairsorblade noticed some confusion between our use of a system
call's return value and errno.  This patch fixes a number of related
bugs -
	using errno instead of a return value
	using a return value instead of errno
	forgetting to negate a error return to get a positive error code

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
index 34bfc1b..362db05 100644
--- a/arch/um/os-Linux/umid.c
+++ b/arch/um/os-Linux/umid.c
@@ -178,14 +178,14 @@
 	fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644);
 	if(fd < 0){
 		printk("Open of machine pid file \"%s\" failed: %s\n",
-		       file, strerror(-fd));
+		       file, strerror(errno));
 		return;
 	}
 
 	snprintf(pid, sizeof(pid), "%d\n", getpid());
 	n = write(fd, pid, strlen(pid));
 	if(n != strlen(pid))
-		printk("Write of pid file failed - err = %d\n", -n);
+		printk("Write of pid file failed - err = %d\n", errno);
 
 	close(fd);
 }