QMI fails to release client

Sai Chaitanya msaichaitanya at gmail.com
Thu Apr 8 12:41:32 UTC 2021

Hej, sorry for the delayed reply. I am using libqmi 1.26. Here are some
more details about the client allocation issue.

Setup: A usb-modem is plugged in and a data connection is started with
qmi_client_wds_start_network(). It succeeds and can ping. Now, if the
module is suddenly pulled out, the application
calls qmi_device_release_client() and qmi_client_wds_stop_network() as a
part of exit process and ends up here:

error: couldn't release client: Cannot write message: Error writing to file
descriptor: No such device

error: operation failed: Cannot write message: Error writing to file
descriptor: No such device

And when we try to fresh start the data connection after plugging the
module back again with qmi_client_wds_start_network()

error: couldn't create client for the  the 'WDS' service: CID allocation
failed in the CTL client: Transaction timed out

So, it looks like some context is not cleaned up smoothly on the modem in
this sudden power off situation? Or is there any other exit APIs required
to be called in such situations?


On Mon, Mar 29, 2021 at 3:32 PM Aleksander Morgado <aleksander at aleksander.es>

> Hey,
> >
> > Yes it happened after qmi_client_wds_stop_network().
> > If I try to use QMI_DEVICE_OPEN_FLAGS_PROXY, it crashes. So I removed it
> for now. I may be missing some pre-condition when using this flag.
> >
> > Setup is Linux based, cdc-wdm+qmi_wwan.
> >
> Can you debug that crash?, e.g building with debug symbols and running
> under gdb
> Also, what libqmi version are you using?
> --
> Aleksander
> https://aleksander.es

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