usb: gadget: Add support for USB MIDI 2.0 function driver

Hi,

Static analysis has found a minor issue in the following commit:

commit 8b645922b22303cec4628dbbbf6c8553d1cdec87

Author: Takashi Iwai <[email protected]>
Date:   Tue Jul 25 08:22:00 2023 +0200

usb: gadget: Add support for USB MIDI 2.0 function driver

The issue is in function f_midi2_set_alt in drivers/usb/gadget/function/f_midi2.c as follows:

        if (intf != midi2->midi_if || alt > 1)
                return 0;

        if (alt == 0)
                op_mode = MIDI_OP_MODE_MIDI1;
        else if (alt == 1)
                op_mode = MIDI_OP_MODE_MIDI2;
        else
                op_mode = MIDI_OP_MODE_UNSET;

the first if statement will return if alt is 2 or more, so at the following cascaded if/else if/else statement alt is either 0 or 1, hence the final else that sets op_mode = MIDI_OP_MODE_UNSET can never be reached.

Either the last else statement is redundant and can be removed, or the first if statement needs to check for alt > 2 rather than > 1. I'm not sure which one is the valid fix to make. Any ideas?

Colin

We can fix in either way, as it won't happen practically :) I guess I thought of alt < 0, but it's an unsigned int, so this is nonsense. I'd rather drop the redundant else statement.

thanks,

Takashi