firmware: arm_scmi: Fix signed error return values handling

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@linaro.org>
Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/20230718085529.258899-1-sukrut.bellary@linux.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scmi/raw_mode.c b/drivers/firmware/arm_scmi/raw_mode.c
index 6971dcf..0493aa3 100644 (file)
--- 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;