- @cport: cport id
- @hdr: greybus operation header
- @payload: greybus message payload
- */
+struct hdlc_greybus_frame {
- __le16 cport;
- struct gb_operation_msg_hdr hdr;
- u8 payload[];
+} __packed;
- static void hdlc_rx_greybus_frame(struct gb_beagleplay *bg, u8 *buf, u16 len) {
- u16 cport_id;
- struct gb_operation_msg_hdr *hdr = (struct gb_operation_msg_hdr *)buf;
- struct hdlc_greybus_frame *gb_frame = (struct hdlc_greybus_frame *)buf;
- u16 cport_id = le16_to_cpu(gb_frame->cport);
- memcpy(&cport_id, hdr->pad, sizeof(cport_id));
- /* Ensure that the greybus message is valid */
- if (le16_to_cpu(gb_frame->hdr.size) > len - sizeof(cport_id)) {
dev_warn_ratelimited(&bg->sd->dev, "Invalid/Incomplete greybus message");Don't spam the kernel log for corrupted data on the line, that would be a mess. Use a tracepoint?
return;- }
dev_dbg(&bg->sd->dev, "Greybus Operation %u type %X cport %u status %u received",
hdr->operation_id, hdr->type, le16_to_cpu(cport_id), hdr->result);
gb_frame->hdr.operation_id, gb_frame->hdr.type, cport_id, gb_frame->hdr.result);Better yet, put the error in the debug message?
Shouldn't corrupt data be a warning rather than debug message, since it indicates something wrong with the transport?
- greybus_data_rcvd(bg->gb_hd, le16_to_cpu(cport_id), buf, len);
- greybus_data_rcvd(bg->gb_hd, cport_id, &buf[sizeof(cport_id)],
Fun with pointer math. This feels really fragile, why not just point to the field instead?
It seems that taking address of members of packed structures is not valid. I get the `address-of-packed-member` warnings. Is it fine to ignore those in kernel?
} static void hdlc_rx_dbg_frame(const struct gb_beagleplay *bg, const char *buf, u16 len) @@ -339,7 +357,7 @@ static struct serdev_device_ops gb_beagleplay_ops = { static int gb_message_send(struct gb_host_device *hd, u16 cport, struct gb_message *msg, gfp_t mask) { struct gb_beagleplay *bg = dev_get_drvdata(&hd->dev);
- struct hdlc_payload payloads[2];
- struct hdlc_payload payloads[3];
why 3?
It's ok to put this on the stack?
Well, the HDLC payload is just to store the length of the payload along with a pointer to its data. (kind of emulate a fat pointer). The reason for doing it this way is to avoid having to create a temp buffer for each message when sending data over UART (which was done in the initial version of the driver).
Ayush Singh