On Sat, 11 May 2024, Christoph Fritz wrote:
> ...
> > > diff --git a/drivers/hid/hid-hexdev-hexlin.c b/drivers/hid/hid-hexdev-hexlin.c
> > > new file mode 100644
> > > index 0000000000000..a9ed080b3e33e
> > > --- /dev/null
> > > +++ b/drivers/hid/hid-hexdev-hexlin.c
> > >
> ...
> >
> > > +}
> > > +
> > > +#define HEXLIN_GET_CMD(name, enum_cmd) \
> > > + static int hexlin_##name(struct hexlin_priv_data *p) \
> > > + { \
> > > + u8 *req; \
> > > + int ret; \
> > > + \
> > > + req = kmalloc(sizeof(*req), GFP_KERNEL) ; \
> >
> > Extra space.
> >
> > Use:
> >
> > u8 *req __free(kfree) = kmalloc(sizeof(*req), GFP_KERNEL);
> >
> > > + if (!req) \
> > > + return -ENOMEM; \
> > > + \
> > > + *req = enum_cmd; \
> > > + \
> > > + ret = hexlin_tx_req_status(p, req, sizeof(*req)); \
> > > + if (ret) \
> > > + hid_err(p->hid_dev, "%s failed, error: %d\n", \
> > > + #name, ret); \
> > > + \
> > > + kfree(req); \
> >
> > Not needed after using __free().
> >
> > > + return ret; \
> > > + }
> > > +
> > > +HEXLIN_GET_CMD(get_version, HEXLIN_GET_VERSION)
> > > +HEXLIN_GET_CMD(reset_dev, HEXLIN_RESET)
> > > +HEXLIN_GET_CMD(get_baudrate, HEXLIN_GET_BAUDRATE)
> >
> > Could you convert the function in the macro into a helper function which
> > is just called by a simple function with the relevant parameters for
> > these 3 cases?
>
> The device actually has a lot more features that I'm using in my debug
> version and which might end up here in the future. So I would like to
> keep it. Any objections?
I don't follow, HEXLIN_GET_CMD() will always produce a copy of that same
function even if you use it 1000 times?? (Except for the enum and string
which can easily be passed as arguments to a common function).
You can still keep HEXLIN_GET_CMD() which just calls that common function
if you want to avoid giving those two parameters directly.
> > > +static int hexlin_set_baudrate(struct hexlin_priv_data *priv, u16 baudrate)
> > > +{
> > > + struct hexlin_baudrate_req *req;
> > > + int ret;
> > > +
> > > + if (baudrate < LIN_MIN_BAUDRATE || baudrate > LIN_MAX_BAUDRATE)
> > > + return -EINVAL;
> > > +
> > > + req = kmalloc(sizeof(*req), GFP_KERNEL);
> >
> > Hmm... Why do you alloc this small structure (3 bytes?) with kmalloc() and
> > not just have it in stack as a local variable?
>
> This buffer must be suitable for DMA (see docu for struct urb).
>
> So with a stack variable we would need to use kmemdup() before the
> actual sending call, but that's what you did not like since v3 so I
> changed it to this which now you also don't like.
>
> Let's dial it back to the original kmemdup() usage, ok?
I asked a question. Since you have a good reason for alloc, just keep the
alloc then.
Now I notice it's kmalloc(), why not kzalloc()?
> > > +static int hexlin_queue_frames_insert(struct hexlin_priv_data *priv,
> > > + const struct hexlin_frame *hxf)
> > > +{
> > > + struct hid_device *hdev = priv->hid_dev;
> > > + struct lin_frame lf;
> > > +
> > > + lf.len = hxf->len;
> > > + lf.lin_id = hxf->lin_id;
> > > + memcpy(lf.data, hxf->data, LIN_MAX_DLEN);
> > > + lf.checksum = hxf->checksum;
> > > + lf.checksum_mode = hxf->checksum_mode;
> > > +
> > > + hid_dbg(hdev, "id:%02x, len:%u, data:%*ph, chk:%02x (%s), flg:%08x\n",
> > > + lf.lin_id, lf.len, lf.len, lf.data, lf.checksum,
> > > + lf.checksum_mode ? "enhanced" : "classic", hxf->flags);
> > > +
> > > + lin_rx(priv->ldev, &lf);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int hexlin_raw_event(struct hid_device *hdev,
> > > + struct hid_report *report, u8 *data, int sz)
> > > +{
> > > + struct hexlin_priv_data *priv;
> > > + struct hexlin_baudrate_req *br;
> > > + struct hexlin_responder_answer_req *rar;
> > > + struct hexlin_unconditional_req *hfr;
> > > + struct hexlin_val8_req *vr;
> > > +
> > > + if (sz < 1 || sz > HEXLIN_PKGLEN_MAX)
> > > + return -EREMOTEIO;
> > > +
> > > + priv = hid_get_drvdata(hdev);
> > > +
> > > + hid_dbg(hdev, "%s, size:%i, data[0]: 0x%02x\n", __func__, sz, data[0]);
> > > +
> > > + priv->is_error = false;
> > > +
> > > + switch (data[0]) {
> > > + case HEXLIN_SUCCESS:
> > > + if (sz != HEXLIN_LEN_RETCODE)
> > > + return -EREMOTEIO;
> > > + hid_dbg(hdev, "HEXLIN_SUCCESS: 0x%02x\n", data[0]);
> > > + complete(&priv->wait_in_report);
> > > + break;
> > > + case HEXLIN_FAIL:
> > > + if (sz != HEXLIN_LEN_RETCODE)
> > > + return -EREMOTEIO;
> > > + hid_err(hdev, "HEXLIN_FAIL: 0x%02x\n", data[0]);
> > > + priv->is_error = true;
> > > + complete(&priv->wait_in_report);
> > > + break;
> > > + case HEXLIN_GET_VERSION:
> > > + if (sz != sizeof(*vr))
> > > + return -EREMOTEIO;
> > > + vr = (struct hexlin_val8_req *) data;
> > > + priv->fw_version = vr->v;
> > > + complete(&priv->wait_in_report);
> > > + break;
> > > + case HEXLIN_GET_RESPONDER_ANSWER_ID:
> > > + if (sz != sizeof(*rar))
> > > + return -EREMOTEIO;
> > > + rar = (struct hexlin_responder_answer_req *) data;
> > > + memcpy(&priv->answ, &rar->answ, sizeof(priv->answ));
> > > + complete(&priv->wait_in_report);
> > > + break;
> > > + case HEXLIN_GET_BAUDRATE:
> > > + if (sz != sizeof(*br))
> > > + return -EREMOTEIO;
> > > + br = (struct hexlin_baudrate_req *) data;
> > > + le16_to_cpus(br->baudrate);
> > > + priv->baudrate = br->baudrate;
> > > + complete(&priv->wait_in_report);
> > > + break;
> > > + /* following cases not initiated by us, so no complete() */
> > > + case HEXLIN_FRAME:
> > > + if (sz != sizeof(*hfr)) {
> > > + hid_err_once(hdev, "frame size mismatch: %i\n", sz);
> > > + return -EREMOTEIO;
> > > + }
> > > + hfr = (struct hexlin_unconditional_req *) data;
> > > + le32_to_cpus(hfr->frm.flags);
> >
> > I'm bit worried about this from endianness perspective. Perhaps there's
> > some struct reusing that shouldn't be happening because the same field
> > cannot be __le32 and u32 at the same time.
>
> Can you propose a solution?
Just do a le32_to_cpu(hfr->frm.flags) in the debug print's arguments?
--
i.
