[PATCH] mtd: spi-nor: reduce stack usage in spi_nor_parse_sfdp()

[Arnd Bergmann]

From: Arnd Bergmann <arnd@xxxxxxxx>

Two large spi_nor_flash_parameter structures on a function stack
is really too much, and this can exceed an otherwise reasonable
frame limit:

drivers/mtd/spi-nor/sfdp.c: In function 'spi_nor_parse_sfdp':
drivers/mtd/spi-nor/sfdp.c:1717:1: error: the frame size of 1600 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]

Change one of them to a dynamic allocation to make this more reasonable.

Fixes: d20029474a76 ("mtd: spi-nor: push the rollback mechanism into the sfdp module")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 drivers/mtd/spi-nor/sfdp.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index c21a6953db96..5d0901074f50 100644
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -1520,7 +1520,7 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
 {
 	const struct sfdp_parameter_header *param_header, *bfpt_header;
 	struct sfdp_parameter_header *param_headers = NULL;
-	struct spi_nor_flash_parameter params, params2;
+	struct spi_nor_flash_parameter __free(kfree) *params = NULL;
 	struct sfdp_header header;
 	struct device *dev = nor->dev;
 	struct sfdp *sfdp;
@@ -1532,7 +1532,9 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
 	 * Get a backup of all the parameter to roll back to in case of an
 	 * error.
 	 */
-	memcpy(&params, nor->params, sizeof(params));
+	params = kmemdup(nor->params, sizeof(*params), GFP_KERNEL);
+	if (!params)
+		return -ENOMEM;
 
 	/* Get the SFDP header. */
 	err = spi_nor_read_sfdp_dma_unsafe(nor, 0, sizeof(header), &header);
@@ -1652,6 +1654,8 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
 
 	/* Parse optional parameter tables. */
 	for (i = 0; i < header.nph; i++) {
+		struct spi_nor_flash_parameter params2;
+
 		memcpy(&params2, nor->params, sizeof(params2));
 		param_header = &param_headers[i];
 
@@ -1711,7 +1715,7 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
 free_param_headers:
 	kfree(param_headers);
 	if (err)
-		memcpy(nor->params, &params, sizeof(*nor->params));
+		memcpy(nor->params, params, sizeof(*nor->params));
 
 	return err;
 }
-- 
2.53.0