linux-kernel - [PATCH v3] mtd: rawnand: Fix return value check of wait_for_completion

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Message-Id: <20220412083435.29254-1-linmq006@gmail.com>
Date:   Tue, 12 Apr 2022 08:34:31 +0000
From:   Miaoqian Lin <linmq006@...il.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Paul Cercueil <paul@...pouillou.net>,
        Miaoqian Lin <linmq006@...il.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Pratyush Yadav <p.yadav@...com>,
        Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
        Bastian Hecht <hechtb@...glemail.com>,
        Guennadi Liakhovetski <g.liakhovetski@....de>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3] mtd: rawnand: Fix return value check of wait_for_completion_timeout

wait_for_completion_timeout() returns unsigned long not int.
It returns 0 if timed out, and positive if completed.
The check for <= 0 is ambiguous and should be == 0 here
indicating timeout which is the only error case.

Fixes: 83738d87e3a0 ("mtd: sh_flctl: Add DMA capabilty")
Signed-off-by: Miaoqian Lin <linmq006@...il.com>
---
change in v2:
- initialize ret to 1.
---
changes in v3:
- initialize ret to 0, now ret==0 means success.
- update condition check in caller.
---
 drivers/mtd/nand/raw/sh_flctl.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/raw/sh_flctl.c b/drivers/mtd/nand/raw/sh_flctl.c
index b85b9c6fcc42..a278829469d6 100644
--- a/drivers/mtd/nand/raw/sh_flctl.c
+++ b/drivers/mtd/nand/raw/sh_flctl.c
@@ -384,7 +384,8 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
 	dma_addr_t dma_addr;
 	dma_cookie_t cookie;
 	uint32_t reg;
-	int ret;
+	int ret = 0;
+	unsigned long time_left;
 
 	if (dir == DMA_FROM_DEVICE) {
 		chan = flctl->chan_fifo0_rx;
@@ -425,13 +426,14 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
 		goto out;
 	}
 
-	ret =
+	time_left =
 	wait_for_completion_timeout(&flctl->dma_complete,
 				msecs_to_jiffies(3000));
 
-	if (ret <= 0) {
+	if (time_left == 0) {
 		dmaengine_terminate_all(chan);
 		dev_err(&flctl->pdev->dev, "wait_for_completion_timeout\n");
+		ret = -ETIMEDOUT;
 	}
 
 out:
@@ -441,7 +443,7 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
 
 	dma_unmap_single(chan->device->dev, dma_addr, len, dir);
 
-	/* ret > 0 is success */
+	/* ret == 0 is success */
 	return ret;
 }
 
@@ -465,7 +467,7 @@ static void read_fiforeg(struct sh_flctl *flctl, int rlen, int offset)
 
 	/* initiate DMA transfer */
 	if (flctl->chan_fifo0_rx && rlen >= 32 &&
-		flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_FROM_DEVICE) > 0)
+		!flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_FROM_DEVICE))
 			goto convert;	/* DMA success */
 
 	/* do polling transfer */
@@ -524,7 +526,7 @@ static void write_ec_fiforeg(struct sh_flctl *flctl, int rlen,
 
 	/* initiate DMA transfer */
 	if (flctl->chan_fifo0_tx && rlen >= 32 &&
-		flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_TO_DEVICE) > 0)
+		!flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_TO_DEVICE))
 			return;	/* DMA success */
 
 	/* do polling transfer */
-- 
2.17.1