[PATCH 5.15 119/230] tty: n_gsm: Save dlci address open status when config requester

Greg Kroah-Hartman
2022-07-11T09:51:27Z

From: Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>

[ Upstream commit 0b91b5332368f2fb0c3e5cfebc6aff9e167acd8b ]

When n_gsm config "initiator=0",as requester ,receive SABM frame,n_gsm
register gsmtty dev,and save dlci open address status,if receive DLC0
DISC or CLD frame,it can unregister the gsmtty dev by saving dlci address.

Signed-off-by: Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>
Link: https://lore.kernel.org/r/1629461872-26965-8-git-send-email-zhenguo6858@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/n_gsm.c | 57 +++++++++++++++++++++++++++++++++++++++++----
1 file changed, 53 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 91ce8e6e889a..3038e5631be5 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -274,6 +274,10 @@ static DEFINE_SPINLOCK(gsm_mux_lock);

static struct tty_driver *gsm_tty_driver;

+/* Save dlci open address */
+static int addr_open[256] = { 0 };
+/* Save dlci open count */
+static int addr_cnt;
/*
* This section of the driver logic implements the GSM encodings
* both the basic and the 'advanced'. Reliable transport is not
@@ -1191,6 +1195,7 @@ static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
}

static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
+static void gsm_dlci_close(struct gsm_dlci *dlci);

/**
* gsm_control_message - DLCI 0 control processing
@@ -1209,15 +1214,28 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
{
u8 buf[1];
unsigned long flags;
+ struct gsm_dlci *dlci;
+ int i;
+ int address;

switch (command) {
case CMD_CLD: {
- struct gsm_dlci *dlci = gsm->dlci[0];
+ if (addr_cnt > 0) {
+ for (i = 0; i < addr_cnt; i++) {
+ address = addr_open[i];
+ dlci = gsm->dlci[address];
+ gsm_dlci_close(dlci);
+ addr_open[i] = 0;
+ }
+ }
/* Modem wishes to close down */
+ dlci = gsm->dlci[0];
if (dlci) {
dlci->dead = true;
gsm->dead = true;
- gsm_dlci_begin_close(dlci);
+ gsm_dlci_close(dlci);
+ addr_cnt = 0;
+ gsm_response(gsm, 0, UA|PF);
}
}
break;
@@ -1780,6 +1798,7 @@ static void gsm_queue(struct gsm_mux *gsm)
struct gsm_dlci *dlci;
u8 cr;
int address;
+ int i, j, k, address_tmp;
/* We have to sneak a look at the packet body to do the FCS.
A somewhat layering violation in the spec */

@@ -1822,6 +1841,11 @@ static void gsm_queue(struct gsm_mux *gsm)
else {
gsm_response(gsm, address, UA|PF);
gsm_dlci_open(dlci);
+ /* Save dlci open address */
+ if (address) {
+ addr_open[addr_cnt] = address;
+ addr_cnt++;
+ }
}
break;
case DISC|PF:
@@ -1832,8 +1856,33 @@ static void gsm_queue(struct gsm_mux *gsm)
return;
}
/* Real close complete */
- gsm_response(gsm, address, UA|PF);
- gsm_dlci_close(dlci);
+ if (!address) {
+ if (addr_cnt > 0) {
+ for (i = 0; i < addr_cnt; i++) {
+ address = addr_open[i];
+ dlci = gsm->dlci[address];
+ gsm_dlci_close(dlci);
+ addr_open[i] = 0;
+ }
+ }
+ dlci = gsm->dlci[0];
+ gsm_dlci_close(dlci);
+ addr_cnt = 0;
+ gsm_response(gsm, 0, UA|PF);
+ } else {
+ gsm_response(gsm, address, UA|PF);
+ gsm_dlci_close(dlci);
+ /* clear dlci address */
+ for (j = 0; j < addr_cnt; j++) {
+ address_tmp = addr_open[j];
+ if (address_tmp == address) {
+ for (k = j; k < addr_cnt; k++)
+ addr_open[k] = addr_open[k+1];
+ addr_cnt--;
+ break;
+ }
+ }
+ }
break;
case UA|PF:
if (cr == 0 || dlci == NULL)
--
2.35.1