linux-kernel - [PATCH v4] mtd: cfi: fix deadloop in cfi_cmdset_0002.c do_write

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Date:   Wed, 27 Mar 2019 23:03:53 +0800
From:   Liu Jian <liujian56@...wei.com>
To:     <dwmw2@...radead.org>, <computersforpeace@...il.com>,
        <bbrezillon@...nel.org>, <marek.vasut@...il.com>, <richard@....at>,
        <joakim.tjernlund@...inera.com>, <ikegami@...ied-telesis.co.jp>,
        <keescook@...omium.org>, <vigneshr@...com>
CC:     <liujian56@...wei.com>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v4] mtd: cfi: fix deadloop in cfi_cmdset_0002.c do_write_buffer

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
not good status for a while.

Fixes: dfeae1073583("mtd: cfi_cmdset_0002: Change write buffer to check correct value")
Signed-off-by: Yi Huaijie <yihuaijie@...wei.com>
Signed-off-by: Liu Jian <liujian56@...wei.com>
Reviewed-by: Tokunori Ikegami <ikegami_to@...oo.co.jp>
---
v3-v4:
1. add "mtd: " prefix to subject
2. add some comment suggested by reviewers

I forgot to resend this patch, I am very sorry.

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

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index 72428b6..bcabc50 100644
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -1876,7 +1876,11 @@ 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" && "!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)) {
-- 
2.7.4