[PATCH] firmware: arm_scmi: Fix signed error return values handling

[Sukrut Bellary]

Handle signed error return values returned by simple_write_to_buffer().
In case of an error, return the error code.

Fixes: 3c3d818a9317 ("firmware: arm_scmi: Add core raw transmission support")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Sukrut Bellary <sukrut.bellary@xxxxxxxxx>
---
This is based on static analysis. Compilation tested.
---
 drivers/firmware/arm_scmi/raw_mode.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scmi/raw_mode.c b/drivers/firmware/arm_scmi/raw_mode.c
index 6971dcf72fb9..0493aa3c12bf 100644
--- a/drivers/firmware/arm_scmi/raw_mode.c
+++ b/drivers/firmware/arm_scmi/raw_mode.c
@@ -818,10 +818,13 @@ static ssize_t scmi_dbg_raw_mode_common_write(struct file *filp,
 	 * before sending it with a single RAW xfer.
 	 */
 	if (rd->tx_size < rd->tx_req_size) {
-		size_t cnt;
+		ssize_t cnt;
 
 		cnt = simple_write_to_buffer(rd->tx.buf, rd->tx.len, ppos,
 					     buf, count);
+		if (cnt < 0)
+			return cnt;
+
 		rd->tx_size += cnt;
 		if (cnt < count)
 			return cnt;
-- 
2.34.1