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Date: Tue, 13 Apr 2021 20:48:44 +0100
From: Matthew Wilcox <willy@infradead.org>
To: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Julia Lawall <julia.lawall@inria.fr>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	outreachy-kernel@googlegroups.com,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [Outreachy kernel] [PATCH] :staging: rtl8723bs: Remove useless
 led_blink_hdl()
Message-ID: <20210413194844.GR2531743@casper.infradead.org>
References: <20210413155908.8691-1-fmdefrancesco@gmail.com>
 <2400087.QbMOWSuNhY@linux.local>
 <alpine.DEB.2.22.394.2104132123180.14108@hadrien>
 <7008359.Jy8utYDuns@linux.local>
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In-Reply-To: <7008359.Jy8utYDuns@linux.local>

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;