On Wed, Feb 28, 2018 at 10:17:50PM +0200, Andy Shevchenko wrote:
> On Wed, Feb 28, 2018 at 8:43 PM, Rodrigo Rivas Costa
> <rodrigorivascosta@xxxxxxxxx> wrote:
> > This device has a feature report to send and receive commands.
> > Use it to get the serial number and set the device's uniq value.
>
> > #include <linux/module.h>
> > #include <linux/workqueue.h>
> > #include <linux/rcupdate.h>
>
> > +#include <linux/delay.h>
>
> Better to keep it somehow sorted (yes, I see it's not originally, but
> better to squeeze new header to the most ordered part).
Do you mean alphabetically? Or by topic/submodule? I just added it to
the end of the include list.
>
>
> > @@ -41,8 +42,99 @@ struct steam_device {
> > unsigned long quirks;
> > struct work_struct work_connect;
> > bool connected;
>
> > + char serial_no[11];
>
> 11 is a magic.
Magic indeed, it is 10 because the Valve protocol says so, and +1 for
the NUL. I'll add a #define for that 10.
>
> > };
> >
> > +static int steam_recv_report(struct steam_device *steam,
> > + u8 *data, int size)
> > +{
> > + struct hid_report *r;
> > + u8 *buf;
> > + int ret;
> > +
> > + r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];
> > + if (hid_report_len(r) < 64)
> > + return -EINVAL;
>
> + empty line.
Ok.
>
> > + buf = hid_alloc_report_buf(r, GFP_KERNEL);
> > + if (!buf)
> > + return -ENOMEM;
> > +
> > + /*
> > + * The report ID is always 0, so strip the first byte from the output.
> > + * hid_report_len() is not counting the report ID, so +1 to the length
> > + * or else we get a EOVERFLOW. We are safe from a buffer overflow
> > + * because hid_alloc_report_buf() allocates +7 bytes.
> > + */
> > + ret = hid_hw_raw_request(steam->hdev, 0x00,
> > + buf, hid_report_len(r) + 1,
> > + HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
> > + if (ret > 0)
> > + memcpy(data, buf + 1, min(size, ret - 1));
> > + kfree(buf);
> > + return ret;
> > +}
> > +
> > +static int steam_send_report(struct steam_device *steam,
> > + u8 *cmd, int size)
> > +{
> > + struct hid_report *r;
> > + u8 *buf;
> > + int retry;
> > + int ret;
> > +
> > + r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];
> > + if (hid_report_len(r) < 64)
> > + return -EINVAL;
>
> +empty line.
Ok.
>
> > + buf = hid_alloc_report_buf(r, GFP_KERNEL);
> > + if (!buf)
> > + return -ENOMEM;
> > +
> > + /* The report ID is always 0 */
> > + memcpy(buf + 1, cmd, size);
> > +
> > + /*
> > + * Sometimes the wireless controller fails with EPIPE
> > + * when sending a feature report.
> > + * Doing a HID_REQ_GET_REPORT and waiting for a while
> > + * seems to fix that.
> > + */
>
> > + for (retry = 0; retry < 10; ++retry) {
> > + ret = hid_hw_raw_request(steam->hdev, 0,
> > + buf, size + 1,
> > + HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
> > + if (ret != -EPIPE)
> > + break;
> > + steam_recv_report(steam, NULL, 0);
> > + msleep(50);
> > + }
>
> Personally I consider do{}while in case of "timeout loops" much easier to parse.
>
> unsigned int retry = 10;
> ...
>
> do {
> ...
> } while (--retry);
>
Ok, it looks like it is done this way in most places. Also renamed to 'retries'.
> > + kfree(buf);
> > + if (ret < 0)
> > + hid_err(steam->hdev, "%s: error %d (%*ph)\n", __func__,
> > + ret, size, cmd);
> > + return ret;
> > +}
> > +
> > +static int steam_get_serial(struct steam_device *steam)
> > +{
> > + /*
> > + * Send: 0xae 0x15 0x01
> > + * Recv: 0xae 0x15 0x01 serialnumber (10 chars)
> > + */
> > + int ret;
> > + u8 cmd[] = {0xae, 0x15, 0x01};
>
> > + u8 reply[14];
> > +
> > + ret = steam_send_report(steam, cmd, sizeof(cmd));
> > + if (ret < 0)
> > + return ret;
> > + ret = steam_recv_report(steam, reply, sizeof(reply));
> > + if (ret < 0)
> > + return ret;
>
>
> > + reply[13] = 0;
> > + strcpy(steam->serial_no, reply + 3);
>
> strlcpy()
Well, I've set a NUL byte at the end so the overflow is impossible.
I'll change it anyway, for extra safety.
>
> > + return 0;
> > +}
>
>
> --
> With Best Regards,
> Andy Shevchenko
Regards.
Rodrigo
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