[PATCH 4.9 61/80] mtd: cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer

[Greg Kroah-Hartman]

From: Liu Jian <liujian56@xxxxxxxxxx>

commit d9b8a67b3b95a5c5aae6422b8113adc1c2485f2b 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: dfeae1073583("mtd: cfi_cmdset_0002: Change write buffer to check correct value")
Signed-off-by: Yi Huaijie <yihuaijie@xxxxxxxxxx>
Signed-off-by: Liu Jian <liujian56@xxxxxxxxxx>
Reviewed-by: Tokunori Ikegami <ikegami_to@xxxxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/mtd/chips/cfi_cmdset_0002.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -1879,7 +1879,11 @@ static int __xipram do_write_buffer(stru
 			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)) {