linux-kernel - Re: [PATCH] taging: speakup: remove volatile

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Date:   Fri, 22 May 2020 11:21:46 +0200
From:   Samuel Thibault <samuel.thibault@...-lyon.org>
To:     MugilRaj <dmugil2000@...il.com>
Cc:     William Hubbs <w.d.hubbs@...il.com>,
        Chris Brannon <chris@...-brannons.com>,
        Kirk Reiser <kirk@...sers.ca>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        speakup@...ux-speakup.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] taging: speakup: remove volatile

Hello,

MugilRaj, le ven. 22 mai 2020 14:46:28 +0530, a ecrit:
> fix checkpatch.pl warning, which is Use of volatile is usually wrong: see
> Documentation/process/volatile-considered-harmful.rst

Yes, but the proper fix is usually not to just remove the volatile
qualifier, which will not fix anything and potentially break things.

Fixing this requires really understanding what is at stake here, between
the read_buff_add function and the use of synth_full(). That goes
through interrupt handlers, tty disciplines, and the actual behavior
expected by speakup. Not a simple task, henceforth :)

> Signed-off-by: MugilRaj <dmugil2000@...il.com>
> ---
>  drivers/staging/speakup/speakup_decext.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/speakup/speakup_decext.c b/drivers/staging/speakup/speakup_decext.c
> index ddbb7e9..22baaeb 100644
> --- a/drivers/staging/speakup/speakup_decext.c
> +++ b/drivers/staging/speakup/speakup_decext.c
> @@ -21,7 +21,7 @@
>  #define SYNTH_CLEAR 0x03
>  #define PROCSPEECH 0x0b
>  
> -static volatile unsigned char last_char;
> +static unsigned char last_char;
>  
>  static void read_buff_add(u_char ch)
>  {
> -- 
> 2.7.4
>