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This patch fixes a regression on setting up asynchronous commands to use external trigger sources when board-specific routing information is missing. `ni_find_device_routes()` (called via `ni_assign_device_routes()`) finds the table of register values for the device family and the set of valid routes for the specific board. If both are found, `tables->route_values` is set to point to the table of register values for the device family and `tables->valid_routes` is set to point to the list of valid routes for the specific board. If either is not found, both `tables->route_values` and `tables->valid_routes` are left set at their initial null values (initialized by `ni_assign_device_routes()`) and the function returns `-ENODATA`. Returning an error results in some routing functionality being disabled. Unfortunately, leaving `table->route_values` set to `NULL` also breaks the setting up of asynchronous commands that are configured to use external trigger sources. Calls to `ni_check_trigger_arg()` or `ni_check_trigger_arg_roffs()` while checking the asynchronous command set-up would result in a null pointer dereference if `table->route_values` is `NULL`. The null pointer dereference is fixed in another patch, but it now results in failure to set up the asynchronous command. That is a regression from the behavior prior to commit347e244884("staging: comedi: tio: implement global tio/ctr routing") and commit56d0b826d3("staging: comedi: ni_mio_common: implement new routing for TRIG_EXT"). Change `ni_find_device_routes()` to set `tables->route_values` and/or `tables->valid_routes` to valid information even if the other one can only be set to `NULL` due to missing information. The function will still return an error in that case. This should result in `tables->valid_routes` being valid for all currently supported device families even if the board-specific routing information is missing. That should be enough to fix the regression on setting up asynchronous commands to use external triggers for boards with missing routing information. Fixes:347e244884("staging: comedi: tio: implement global tio/ctr routing") Fixes:56d0b826d3("staging: comedi: ni_mio_common: implement new routing for TRIG_EXT"). Cc: <stable@vger.kernel.org> # 4.20+ Cc: Spencer E. Olson <olsonse@umich.edu> Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Link: https://lore.kernel.org/r/20200114182532.132058-3-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
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