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 commit 347e244884c3 ("staging: comedi: tio: implement global tio/ctr routing") and commit 56d0b826d39f ("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: 347e244884c3 ("staging: comedi: tio: implement global tio/ctr routing") Fixes: 56d0b826d39f ("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 --- drivers/staging/comedi/drivers/ni_routes.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/comedi/drivers/ni_routes.c b/drivers/staging/comedi/drivers/ni_routes.c index 9627bd1d2a78..8f398b30f5bf 100644 --- a/drivers/staging/comedi/drivers/ni_routes.c +++ b/drivers/staging/comedi/drivers/ni_routes.c @@ -72,9 +72,6 @@ static int ni_find_device_routes(const char *device_family, } }

- if (!rv) - return -ENODATA; - /* Second, find the set of routes valid for this device. */ for (i = 0; ni_device_routes_list[i]; ++i) { if (memcmp(ni_device_routes_list[i]->device, board_name, @@ -84,12 +81,12 @@ static int ni_find_device_routes(const char *device_family, } }

- if (!dr) - return -ENODATA; - tables->route_values = rv; tables->valid_routes = dr;

+ if (!rv || !dr) + return -ENODATA; + return 0; }