kmod: correct documentation of return status of request_module

If request_module() successfully runs modprobe, but modprobe exits with a
non-zero status, then the return value from request_module() will be that
(positive) error status.  So the return from request_module can be:

 negative errno
 zero for success
 positive exit code.

Signed-off-by: NeilBrown <neilb@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/kmod.c

@@ -114,10 +114,11 @@ out:
  * @...: arguments as specified in the format string
  *
  * Load a module using the user mode module loader. The function returns
- * zero on success or a negative errno code on failure. Note that a
+ * zero on success or a negative errno code or positive exit code from
- * successful module load does not mean the module did not then unload
+ * "modprobe" on failure. Note that a successful module load does not mean
- * and exit on an error of its own. Callers must check that the service
+ * the module did not then unload and exit on an error of its own. Callers
- * they requested is now available not blindly invoke it.
+ * must check that the service they requested is now available not blindly
+ * invoke it.
  *
  * If module auto-loading support is disabled then this function
  * becomes a no-operation.