[PATCH] driver core: dd: fix return value of __setup handler

[Randy Dunlap <rdunlap@infradead.org>]

When "driver_async_probe=nulltty" is used on the kernel boot command line,
it causes an Unknown parameter message and the string is added to init's
environment strings, polluting them.

  Unknown kernel command line parameters "BOOT_IMAGE=/boot/bzImage-517rc6
  driver_async_probe=nulltty", will be passed to user space.

 Run /sbin/init as init process
   with arguments:
     /sbin/init
   with environment:
     HOME=/
     TERM=linux
     BOOT_IMAGE=/boot/bzImage-517rc6
     driver_async_probe=nulltty

Change the return value of the __setup function to 1 to indicate
that the __setup option has been handled.

Fixes: 1ea61b68d0f8 ("async: Add cmdline option to specify drivers to be async probed")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Cc: Feng Tang <feng.tang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
---
 drivers/base/dd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-next-20220228.orig/drivers/base/dd.c
+++ linux-next-20220228/drivers/base/dd.c
@@ -810,7 +810,7 @@ static int __init save_async_options(cha
 		pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 
 	strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
-	return 0;
+	return 1;
 }
 __setup("driver_async_probe=", save_async_options);