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

[Colin King (gmail)]

Hi,

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

commit 8b645922b22303cec4628dbbbf6c8553d1cdec87
Author: Takashi Iwai <tiwai@xxxxxxx>
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