arch/um/os-Linux/sys-i386/task_size.c: improve a bit

Improve this code a bit: check sigaction's return value and remove a useless
fflush().
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: WANG Cong <wangcong@zeuux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/os-Linux/sys-i386/task_size.c

@@ -88,7 +88,10 @@ unsigned long os_get_task_size(void)
 	sa.sa_handler = segfault;
 	sigemptyset(&sa.sa_mask);
 	sa.sa_flags = SA_NODEFER;
-	sigaction(SIGSEGV, &sa, &old);
+	if (sigaction(SIGSEGV, &sa, &old)) {
+		perror("os_get_task_size");
+		exit(1);
+	}
 
 	if (!page_ok(bottom)) {
 		fprintf(stderr, "Address 0x%x no good?\n",
@@ -110,11 +113,12 @@ unsigned long os_get_task_size(void)
 
 out:
 	/* Restore the old SIGSEGV handling */
-	sigaction(SIGSEGV, &old, NULL);
-
+	if (sigaction(SIGSEGV, &old, NULL)) {
+		perror("os_get_task_size");
+		exit(1);
+	}
 	top <<= UM_KERN_PAGE_SHIFT;
 	printf("0x%x\n", top);
-	fflush(stdout);
 
 	return top;
 }