mtd: cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer

BugLink: https://bugs.launchpad.net/bugs/1878098

commit d9b8a67b upstream.

In function do_write_buffer(), in the for loop, there is a case
chip_ready() returns 1 while chip_good() returns 0, so it never
break the loop.
To fix this, chip_good() is enough and it should timeout if it stay
bad for a while.

Fixes: dfeae107("mtd: cfi_cmdset_0002: Change write buffer to check correct value")
Signed-off-by: Yi Huaijie <yihuaijie@huawei.com>
Signed-off-by: Liu Jian <liujian56@huawei.com>
Reviewed-by: Tokunori Ikegami <ikegami_to@yahoo.co.jp>
Signed-off-by: Richard Weinberger <richard@nod.at>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/mtd/chips/cfi_cmdset_0002.c

@@ -1881,7 +1881,11 @@ static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
 			continue;
 		}
 
-		if (time_after(jiffies, timeo) && !chip_ready(map, adr))
+		/*
+		 * We check "time_after" and "!chip_good" before checking "chip_good" to avoid
+		 * the failure due to scheduling.
+		 */
+		if (time_after(jiffies, timeo) && !chip_good(map, adr, datum))
 			break;
 
 		if (chip_good(map, adr, datum)) {