| From 4fc6aef56c50f1209600ba0b3009a48880d98b86 Mon Sep 17 00:00:00 2001 |
| From: Ian Abbott <abbotti@mev.co.uk> |
| Date: Tue, 14 Jan 2020 18:25:32 +0000 |
| Subject: [PATCH] staging: comedi: ni_routes: allow partial routing information |
| |
| commit 9fea3a40f6b07de977a2783270c8c3bc82544d45 upstream. |
| |
| 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> |
| Link: https://lore.kernel.org/r/20200114182532.132058-3-abbotti@mev.co.uk |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/staging/comedi/drivers/ni_routes.c b/drivers/staging/comedi/drivers/ni_routes.c |
| index fe96c4ee90b3..88beb0d6c42b 100644 |
| --- a/drivers/staging/comedi/drivers/ni_routes.c |
| +++ b/drivers/staging/comedi/drivers/ni_routes.c |
| @@ -74,9 +74,6 @@ 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, |
| @@ -86,12 +83,12 @@ 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; |
| } |
| |
| -- |
| 2.7.4 |
| |