the cb_data can be used by creating the structure with cb_data_new, and then there are two possibilities: - use it in a single callback function, and destroy it with a call to g_free. Example: - calling function: struct cb_data *cbd = cb_data_new(cb, data); if (g_at_chat_send(chat, buf, NULL, at_cgatt_cb, cbd, g_free) > 0) return; g_free(cbd); - called function (here at_cgatt_cb): static void at_cgatt_cb(gboolean ok, GAtResult *result, gpointer user_data) { struct cb_data *cbd = user_data; ofono_gprs_cb_t cb = cbd->cb; struct ofono_error error; decode_at_error(&error, g_at_result_final_response(result)); cb(&error, cbd->data); } note the absence of explicit g_free(cbd); - pass it through a train of callback functions, adding a reference at each pass cb_data_ref, and removing it with cb_data_unref. the use of cb_data_ref would replace a new object creation, while the use of cb_data_unref the use of g_free. Example: - calling function: struct cb_data *cbd = cb_data_new(cb, data); // no cb_ref at the creation if (g_at_chat_send(chat, buf, NULL, at_lte_set_default_attach_info_cb, cbd, cb_data_unref) > 0) goto end; cb_data_unref(cbd); - called function 1 (at_lte_set_default_attach_info_cb): static void at_lte_set_default_attach_info_cb(gboolean ok, GAtResult *result, gpointer user_data) { struct cb_data *cbd = user_data; cbd = cb_data_ref(cbd); if (g_at_chat_send(chat, buf, NULL, at_cgatt_cb, cbd, cb_data_unref) > 0) return; cb_data_unref(cbd); } - called function 2 (at_cgatt_cb): like above. no call to g_free or cb_data_unref. The terminal function doesn't need to know about the reference scheme. v2: fixed prototype for cb_data_unref to be compatible with g_free --- drivers/atmodem/atutil.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/drivers/atmodem/atutil.h b/drivers/atmodem/atutil.h index f1389a94..aa8b619c 100644 --- a/drivers/atmodem/atutil.h +++ b/drivers/atmodem/atutil.h @@ -104,6 +104,7 @@ char *at_util_get_cgdcont_command(guint cid, enum ofono_gprs_proto proto, const char *apn); struct cb_data { + gint ref_count; void *cb; void *data; void *user; @@ -114,12 +115,37 @@ static inline struct cb_data *cb_data_new(void *cb, void *data) struct cb_data *ret; ret = g_new0(struct cb_data, 1); + ret->ref_count = 1; ret->cb = cb; ret->data = data; return ret; } +static inline struct cb_data *cb_data_ref(struct cb_data *cbd) +{ + if (cbd == NULL) + return NULL; + + g_atomic_int_inc(&cbd->ref_count); + + return cbd; +} + +static inline void cb_data_unref(gpointer user_data) +{ + struct cb_data *cbd = user_data; + gboolean is_zero; + + if (cbd == NULL) + return; + + is_zero = g_atomic_int_dec_and_test(&cbd->ref_count); + + if (is_zero == TRUE) + g_free(cbd); +} + static inline int at_util_convert_signal_strength(int strength) { int result; -- 2.17.1