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From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To:     Jia-Ju Bai <baijiaju1990@gmail.com>
CC:     "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Subject: RE: [PATCH] usb: renesas_usbhs: fix error return code of
 usbhsf_pkt_handler()
Thread-Topic: [PATCH] usb: renesas_usbhs: fix error return code of
 usbhsf_pkt_handler()
Thread-Index: AQHXEzBZLDVGGgTzcUG+Bf2pWnAADap7i1zw
Date:   Tue, 9 Mar 2021 11:59:39 +0000
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References: <20210307090030.22369-1-baijiaju1990@gmail.com>
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Hi Jia-Ju,

Thank you for the patch!

> From: Jia-Ju Bai, Sent: Sunday, March 7, 2021 6:01 PM
>=20
> When __usbhsf_pkt_get() returns NULL to pkt, no error return code of
> usbhsf_pkt_handler() is assigned.

Yes. Also I realized that no error return code of usbhsf_pkt_handler()
was assigned if the type value was unexpected value. So, I'm thinking
initial value of ret should be -EINVAL instead of 0.
---
        int ret =3D 0;  // should be -EINVAL
        int is_done =3D 0;

        /********************  spin lock ********************/
        usbhs_lock(priv, flags);

        pkt =3D __usbhsf_pkt_get(pipe);
        if (!pkt)
                goto __usbhs_pkt_handler_end;

        switch (type) {
        case USBHSF_PKT_PREPARE:
                func =3D pkt->handler->prepare;
                break;
        case USBHSF_PKT_TRY_RUN:
                func =3D pkt->handler->try_run;
                break;
        case USBHSF_PKT_DMA_DONE:
                func =3D pkt->handler->dma_done;
                break;
        default:
                dev_err(dev, "unknown pkt handler\n");
                goto __usbhs_pkt_handler_end;    /// here
        }

        if (likely(func))  /// [1]
                ret =3D func(pkt, &is_done);

[1] This is always true here, so ret is always assigned by the func().
---

> To fix this bug, ret is assigned with -EINVAL in this case.

Just a record: After fixed this, actual behavior is almost the same
except printing error message.

Best regards,
Yoshihiro Shimoda