<!DOCTYPE html> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body> Hello, I am trying to learn how to use the Python API of libqmi. I extended the simple-tester-python.py to press a key and query some information. When trying to get the revision, I get the correct revision, but afterwards I get the error message “free(): double free detected in tcache 2”. I tried the same with getting the model, and same behaviour: Model can be printed and is correct, but then same error message. When I comment out outputA.get_revision() as well as outputB.get_model() (and not print the content, of course), the error message disappears. I saw in documentation ( <a class="moz-txt-link-freetext" href="https://lazka.github.io/pgi-docs/Qmi-1.0/classes/ClientDms.html#Qmi.ClientDms.get_revision_finish">https://lazka.github.io/pgi-docs/Qmi-1.0/classes/ClientDms.html#Qmi.ClientDms.get_revision_finish</a> ) that I shall: “The returned value should be freed with Qmi.MessageDmsGetModelOutput.unref().” But this does not seem to make a difference. Can someone give me a hint, how I can debug and fix this? Where can I find the source code (python and/or C), which is executed, when a Python function like get_revision() or get_model() is called, till something is executed with/in libqmi? Or do I then directly need to debug inside libqmi? PS: I have attached the complete python source code of my current testing. Extension renamed from *.py to *.txt to avoid that mail servers perhaps filter the file. Extracts below in the email. Keypress like ‘r’ are detected to execute the get revision action. And ‘m’ to get the radio module model. All just for testing, far from cleaned up code! I prepared the Linux environment with these commands (on a Raspberry Pi 4 with latest Raspian OS from May 2023) (only one time needed) sudo apt install python3-gi sudo apt install libqmi-glib-dev I execute it like the following: sudo python3 connection-setup-bugreport.py /dev/cdc-wdm0 I assume does not matter, but I use a Quectel module connected via USB. Many thanks! Best regards, Martin Output of my program (once pressing key "r", then restarting program and pressing key "m"): $ sudo python3 connection-setup.py /dev/cdc-wdm0 new_ready wwan0 open_ready allocate_client_DMS_ready allocate_client_DMS_ready: successful CID 45 allocate_client_WDS_ready allocate_client_WDS_ready: successful <Qmi.ClientWds object at 0x7f93b22a00 (QmiClientWds at 0x3b904790)> CID 46 Call function r get_revision_ready Hallo A 2 Hallo B revision: RM520NGLAAR01A07M4G free(): double free detected in tcache 2 Aborted $ sudo python3 connection-setup.py /dev/cdc-wdm0 new_ready wwan0 open_ready allocate_client_DMS_ready allocate_client_DMS_ready: successful CID 46 allocate_client_WDS_ready allocate_client_WDS_ready: successful <Qmi.ClientWds object at 0x7f94076e00 (QmiClientWds at 0x4dd9790)> CID 47 Call function m get_model_ready Hallo A 2 Hallo B model: RM520N-GL free(): double free detected in tcache 2 Aborted $ def get_revision_ready(qmiclient,result,qmidev): print("get_revision_ready") try: outputA = qmiclient.get_revision_finish(result) errorOccured = outputA.get_result() available, revision = outputA.get_revision() # outputA.unref() print("Hallo A") print(sys.getrefcount(outputA)) print("Hallo B") if available == True: print("revision: %s" % revision) else: print("revision: -> error getting capabilities") except GLib.GError as error: sys.stderr.write("Couldn't query revision: %s\n" % error.message) # output.unref() # release_client(qmidev, qmiclient) def get_model_ready(qmiclient,result,qmidev): print("get_model_ready") try: outputB = qmiclient.get_model_finish(result) errorOccured = outputB.get_result() available, model = outputB.get_model() # outputB.unref() print("Hallo A") print(sys.getrefcount(outputB)) print("Hallo B") if available == True: print("model: %s" % model) else: print("model: -> error getting capabilities") except GLib.GError as error: sys.stderr.write("Couldn't query model: %s\n" % error.message) # output.unref() # release_client(qmidev, qmiclient) </body> </html>