[PATCH] mtd: nand: raw: qcom_nandc: handle error pointer from adm prep_slave_sg

[Christian Marangi <ansuelsmth@gmail.com>]

ADM dma engine has changed to also provide error pointer instaed of
plain NULL pointer on invalid configuration of prep_slave_sg function.
Currently this is not handled and an error pointer is detected as a
valid dma_desc. This cause kernel panic as the driver doesn't fail
with an invalid dma engine configuration.

Correctly handle this case by checking if dma_desc is NULL or IS_ERR.

Fixes: 03de6b273805 ("dmaengine: qcom-adm: stop abusing slave_id config")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Cc: stable@vger.kernel.org # v5.17+
---
 drivers/mtd/nand/raw/qcom_nandc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
index 8f80019a9f01..d7eac196dde0 100644
--- a/drivers/mtd/nand/raw/qcom_nandc.c
+++ b/drivers/mtd/nand/raw/qcom_nandc.c
@@ -1054,7 +1054,7 @@ static int prep_adm_dma_desc(struct qcom_nand_controller *nandc, bool read,
 	}
 
 	dma_desc = dmaengine_prep_slave_sg(nandc->chan, sgl, 1, dir_eng, 0);
-	if (!dma_desc) {
+	if (IS_ERR_OR_NULL(dma_desc)) {
 		dev_err(nandc->dev, "failed to prepare desc\n");
 		ret = -EINVAL;
 		goto err;
-- 
2.37.2