Fix buggy kmem_{v}asprintf() functions

When the kvasprintf() call fails they should reset the arguments
by calling va_start()/va_copy() and va_end() inside the loop,
otherwise they'll try to read more arguments rather than starting
over and reading them from the beginning.

Signed-off-by: Ricardo M. Correia <ricardo.correia@oracle.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

module/spl/spl-kmem.c

@@ -245,11 +245,11 @@ kmem_vasprintf(const char *fmt, va_list ap)
 	va_list aq;
 	char *ptr;
 
-	va_copy(aq, ap);
 	do {
+		va_copy(aq, ap);
 		ptr = kvasprintf(GFP_KERNEL, fmt, aq);
+		va_end(aq);
 	} while (ptr == NULL);
-	va_end(aq);
 
 	return ptr;
 }
@@ -261,11 +261,11 @@ kmem_asprintf(const char *fmt, ...)
 	va_list ap;
 	char *ptr;
 
-	va_start(ap, fmt);
 	do {
+		va_start(ap, fmt);
 		ptr = kvasprintf(GFP_KERNEL, fmt, ap);
+		va_end(ap);
 	} while (ptr == NULL);
-	va_end(ap);
 
 	return ptr;
 }