linux-kernel - Re: [PATCH] n_gsm: Fix write handling for zero bytes written

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Date:   Tue, 18 Aug 2020 10:24:22 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Tony Lindgren <tony@...mide.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Gregory CLEMENT <gregory.clement@...tlin.com>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] n_gsm: Fix write handling for zero bytes written

On 17. 08. 20, 15:54, Tony Lindgren wrote:
> If write returns zero we currently end up removing the message
> from the queue. Instead of removing the message, we want to just
> break out of the loop just like we already do for error codes.

When exactly does the only writer (gsmld_output) return zero for
non-zero len parameter?

> Signed-off-by: Tony Lindgren <tony@...mide.com>
> ---
>  drivers/tty/n_gsm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -691,7 +691,8 @@ static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
>  			print_hex_dump_bytes("gsm_data_kick: ",
>  					     DUMP_PREFIX_OFFSET,
>  					     gsm->txframe, len);
> -		if (gsm->output(gsm, gsm->txframe, len) < 0)
> +
> +		if (gsm->output(gsm, gsm->txframe, len) <= 0)
>  			break;
>  		/* FIXME: Can eliminate one SOF in many more cases */
>  		gsm->tx_bytes -= msg->len;
> 

thanks,
-- 
js