linux-kernel - Re: [Outreachy kernel] [PATCH] :staging: rtl8723bs: Remove useless led_blink

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Message-ID: <20210413194844.GR2531743@casper.infradead.org>
Date:   Tue, 13 Apr 2021 20:48:44 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Cc:     Julia Lawall <julia.lawall@...ia.fr>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        outreachy-kernel@...glegroups.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [Outreachy kernel] [PATCH] :staging: rtl8723bs: Remove useless
 led_blink_hdl()

On Tue, Apr 13, 2021 at 09:45:03PM +0200, Fabio M. De Francesco wrote:
> 1) The driver doesn't call that function from anywhere else than the macro.
> 2) You have explained that the macro add its symbol to a slot in an array 
> that would shift all the subsequent elements down if that macro is not used 
> exactly in the line where it is.
> 3) Dan Carpenter said that that array is full of null functions (or empty 
> slots?).
> 
> Unless that function is called anonymously dereferencing its address from 
> the position it occupies in the array, I'm not able to see what else means 
> can any caller use.
> 
> I know I have much less experience than you with C: what can go wrong?

Here's where the driver calls that function:

$ git grep wlancmds drivers/staging/rtl8723bs/
drivers/staging/rtl8723bs/core/rtw_cmd.c:static struct cmd_hdl wlancmds[] = {
drivers/staging/rtl8723bs/core/rtw_cmd.c:               if (pcmd->cmdcode < ARRAY_SIZE(wlancmds)) {
drivers/staging/rtl8723bs/core/rtw_cmd.c:                       cmd_hdl = wlancmds[pcmd->cmdcode].h2cfuns;