[PATCH] qmi: Allow qmi_qmux_device_discover be called from callback

When the gobi modem plugin performs discovery, it checks whether the WMS
service is present in the callback function provided to
qmi_qmux_device_discover().  If the WMS service isn't present (likely
due to a timeout from the modem firmware), device discovery is
re-attempted from within the callback.  This functionality was broken
since the qmux->discover.tid was not set to 0 until after the callback
function returned.  Allow such re-entrant behavior by making a copy of
device discovery func/user_data/destroy members and de-initializing the
discovery structure prior to invoking the callbacks.

Fixes: 217b57328473 ("qmi: Rename and refactor qmi_device_discover")
---
 drivers/qmimodem/qmi.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/qmimodem/qmi.c b/drivers/qmimodem/qmi.c
index b8f46a5b4a0e..0ba2e8b9e352 100644
--- a/drivers/qmimodem/qmi.c
+++ b/drivers/qmimodem/qmi.c
@@ -1152,13 +1152,17 @@ static struct qmi_request *find_control_request(struct qmi_qmux_device *qmux,
 
 static void __qmux_discovery_finished(struct qmi_qmux_device *qmux)
 {
+	qmi_qmux_device_discover_func_t func = qmux->discover.func;
+	void *user_data = qmux->discover.user_data;
+	qmi_destroy_func_t destroy = qmux->discover.destroy;
+
 	l_timeout_remove(qmux->discover.timeout);
-	qmux->discover.func(qmux->discover.user_data);
+	memset(&qmux->discover, 0, sizeof(qmux->discover));
 
-	if (qmux->discover.destroy)
-		qmux->discover.destroy(qmux->discover.user_data);
+	func(user_data);
 
-	memset(&qmux->discover, 0, sizeof(qmux->discover));
+	if (destroy)
+		destroy(user_data);
 }
 
 static void qmux_sync_callback(struct qmi_request *req, uint16_t message,
-- 
2.45.2