Commit 7a121247 authored by Daniel Starke's avatar Daniel Starke Committed by Greg Kroah-Hartman
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tty: n_gsm: introduce macro for minimal unit size 



n_gsm has a minimal protocol overhead of 7 bytes. The current code already
checks whether the configured MRU/MTU size is at least one byte more than
this.

Introduce the macro MIN_MTU to make this value more obvious.

Signed-off-by: default avatarDaniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20221103091743.2119-1-daniel.starke@siemens.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d85bf510

drivers/tty/n_gsm.c

+5 −2
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ module_param(debug, int, 0600); 
 */

#define MAX_MRU 1500

#define MAX_MTU 1500

#define MIN_MTU (PROT_OVERHEAD + 1)

/* SOF, ADDR, CTRL, LEN1, LEN2, ..., FCS, EOF */

#define PROT_OVERHEAD 7

#define	GSM_NET_TX_TIMEOUT (HZ*10)
@@ -2712,7 +2713,9 @@ static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c) 
	if ((c->adaption != 1 && c->adaption != 2) || c->k)

		return -EOPNOTSUPP;

	/* Check the MRU/MTU range looks sane */

	if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)

	if (c->mru < MIN_MTU || c->mtu < MIN_MTU)

		return -EINVAL;

	if (c->mru > MAX_MRU || c->mtu > MAX_MTU)

		return -EINVAL;

	if (c->n2 > 255)

		return -EINVAL;
@@ -3296,7 +3299,7 @@ static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc) 
		return -ENOMEM;

	}

	net->mtu = dlci->gsm->mtu;

	net->min_mtu = 8;

	net->min_mtu = MIN_MTU;

	net->max_mtu = dlci->gsm->mtu;

	mux_net = netdev_priv(net);

	mux_net->dlci = dlci;