[PATCH v2] atmodem: fix crash during context deactivation

[Kalle Valo <kalle.valo@canonical.com>]

[-- Attachment #1: Type: text/plain, Size: 3886 bytes --]

Ofono either crashed or busy looped with my Huawei E1552 3G modem when I
tried to deactivate GPRS context. The reason was that gcd->chat was
unreferenced already in setup_ppp() but the chat was still accessed
later in at_gprs_deactivate_primary().

To fix the problem, change the logic instead to suspend chat session
for PPP and resume when PPP has disconnected. Now it doesn't crash
anymore.

Also remove the CGACT=0 command during deactivation, it's enough to shutdown
ppp.

Deactivation still doesn't work properly with Huawei E1552, and most
probably with other Huawei modems, because the modem hangs up the chat
line after PPP deactivation. This needs to be fixed separately. The
workaround is to reboot the modem, for example physically unplug and plug
it in again.
---

 drivers/atmodem/gprs-context.c |   56 +++++++++++++---------------------------
 1 files changed, 18 insertions(+), 38 deletions(-)

diff --git a/drivers/atmodem/gprs-context.c b/drivers/atmodem/gprs-context.c
index ba5f0c0..794db8a 100644
--- a/drivers/atmodem/gprs-context.c
+++ b/drivers/atmodem/gprs-context.c
@@ -65,22 +65,6 @@ struct gprs_context_data {
 	void *cb_data;                                  /* Callback data */
 };
 
-static void at_cgact_down_cb(gboolean ok, GAtResult *result, gpointer user_data)
-{
-	struct cb_data *cbd = user_data;
-	ofono_gprs_context_cb_t cb = cbd->cb;
-	struct ofono_gprs_context *gc = cbd->user;
-	struct gprs_context_data *gcd = ofono_gprs_context_get_data(gc);
-	struct ofono_error error;
-
-	if (ok)
-		gcd->active_context = 0;
-
-	decode_at_error(&error, g_at_result_final_response(result));
-
-	cb(&error, cbd->data);
-}
-
 static void ppp_connect(const char *interface, const char *ip,
 			const char *dns1, const char *dns2,
 			gpointer user_data)
@@ -104,13 +88,19 @@ static void ppp_disconnect(GAtPPPDisconnectReason reason, gpointer user_data)
 	struct ofono_gprs_context *gc = user_data;
 	struct gprs_context_data *gcd = ofono_gprs_context_get_data(gc);
 
+	DBG("");
+
+	g_at_chat_resume(gcd->chat);
+
 	if (gcd->state == STATE_ENABLING) {
 		CALLBACK_WITH_FAILURE(gcd->up_cb, NULL, FALSE, NULL,
 					NULL, NULL, NULL, gcd->cb_data);
-		return;
+	} else if (gcd->state == STATE_DISABLING) {
+		CALLBACK_WITH_SUCCESS(gcd->down_cb, gcd->cb_data);
+	} else {
+		ofono_gprs_context_deactivated(gc, gcd->active_context);
 	}
 
-	ofono_gprs_context_deactivated(gc, gcd->active_context);
 	gcd->active_context = 0;
 	gcd->state = STATE_IDLE;
 }
@@ -118,13 +108,14 @@ static void ppp_disconnect(GAtPPPDisconnectReason reason, gpointer user_data)
 static gboolean setup_ppp(struct ofono_gprs_context *gc)
 {
 	struct gprs_context_data *gcd = ofono_gprs_context_get_data(gc);
-	GIOChannel *channel;
+	GAtIO *io;
+
+	io = g_at_chat_get_io(gcd->chat);
 
-	channel = g_at_chat_get_channel(gcd->chat);
-	g_at_chat_unref(gcd->chat);
+	g_at_chat_suspend(gcd->chat);
 
 	/* open ppp */
-	gcd->ppp = g_at_ppp_new(channel);
+	gcd->ppp = g_at_ppp_new_from_io(io);
 
 	if (gcd->ppp == NULL)
 		return FALSE;
@@ -227,25 +218,14 @@ static void at_gprs_deactivate_primary(struct ofono_gprs_context *gc,
 					ofono_gprs_context_cb_t cb, void *data)
 {
 	struct gprs_context_data *gcd = ofono_gprs_context_get_data(gc);
-	struct cb_data *cbd = cb_data_new(cb, data);
-	char buf[64];
-
-	if (!cbd)
-		goto error;
-
-	cbd->user = gc;
 
-	snprintf(buf, sizeof(buf), "AT+CGACT=0,%u", id);
+	DBG("");
 
-	if (g_at_chat_send(gcd->chat, buf, none_prefix,
-				at_cgact_down_cb, cbd, g_free) > 0)
-		return;
-
-error:
-	if (cbd)
-		g_free(cbd);
+	gcd->state = STATE_DISABLING;
+	gcd->down_cb = cb;
+	gcd->cb_data = data;
 
-	CALLBACK_WITH_FAILURE(cb, data);
+	g_at_ppp_shutdown(gcd->ppp);
 }
 
 static int at_gprs_context_probe(struct ofono_gprs_context *gc,