linux-kernel - Re: [PATCH 4/4] tty: n_gsm: add ioctl to map serial device to mux'ed tty

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Message-ID: <15a4b2ad-cdb9-a679-156d-62aa6fddb85a@suse.com>
Date:   Tue, 9 Jul 2019 07:35:35 +0200
From:   Jiri Slaby <jslaby@...e.com>
To:     Martin Hundebøll <martin@...nix.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc:     Esben Haabendal <esben@...nix.com>,
        Sean Nyekjær <sean@...nix.com>
Subject: Re: [PATCH 4/4] tty: n_gsm: add ioctl to map serial device to mux'ed
 tty

On 08. 07. 19, 21:02, Martin Hundebøll  wrote:
> Guessing the base tty for a gsm0710 multiplexed serial device is not
> currently possible, which makes it racy to use with multiple modems.
> 
> Add a way to map the physical serial tty to its related mux devices
> using a ioctl.
...
> --- a/Documentation/serial/n_gsm.rst
> +++ b/Documentation/serial/n_gsm.rst
...
> @@ -58,6 +61,11 @@ Major parts of the initialization program :
>  	c.mtu = 127;
>  	/* set the new configuration */
>  	ioctl(fd, GSMIOC_SETCONF, &c);
> +	/* get and print base gsmtty device node */
> +	ioctl(fd, GSMIOC_GETBASE, &base);
> +	/* the base node is used for mux control by the driver */
> +	printf(first muxed line: /dev/gsmtty%i\n", base + 1);

Missing " there.

> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
...
> @@ -2623,6 +2624,11 @@ static int gsmld_ioctl(struct tty_struct *tty, struct file *file,
>  		if (copy_from_user(&c, (void *)arg, sizeof(c)))
>  			return -EFAULT;
>  		return gsm_config(gsm, &c);
> +	case GSMIOC_GETBASE:
> +		base = mux_num_to_base(gsm);
> +		if (copy_to_user((void *)arg, &base, sizeof(base)))

put_user would be more appropriate (and easier) for an int here.

thanks,
-- 
js
suse labs