Recursive calls to "app_sched_execute" in nRF Bootloader flow

RE: Recursive calls to "app_sched_execute" in nRF Bootloader flow

sdaexpert — Wed, 11 Oct 2017 23:02:19 GMT

I am trying to understand how exactly the problem of "recursivity" was solved in the Bootloader's implementation in SDK14. I see that, for instance, in the source code file "nrf_dfu_settings.c" the call to "wait_for_queue()" from "nrf_dfu_settings_write()" function has been removed. (That call in SDK13 was one of the reasons why the "recursive" calls to the "app_sched_execute" could have happen in SDK13).

However, it appears that without the above call to "wait_for_queue()", the calls to nrf_dfu_flash_erase() and nrf_dfu_flash_store() in SDK14 are performed without checking if there is an available room in the command queue "nrf_fstorage_sd_queue_t m_queue" in the "nrf_fstorage" module. Is is possible that the calls to nrf_dfu_flash_erase() and nrf_dfu_flash_store() might fail b/c of no room in that queue is available ? How is that prevented in SDK14 ?

RE: Recursive calls to "app_sched_execute" in nRF Bootloader flow

sdaexpert — Fri, 29 Sep 2017 06:37:13 GMT

I wanted to see if Nordic could possibly provide for the "sub-set" of the changes between SDK13 and SDK14 which actually implement the fix for the "recursivity" problem of the DFU bootloader in SDK13. The reason for the question is that we have a "production-level" DFU bootloader based on SDK13 which we would like to "patch up" to fix that problem. Porting the whole bootloader from SDK 14 is not desirable in our case given our time frame

RE: Recursive calls to "app_sched_execute" in nRF Bootloader flow

bjorn-spockeli — Thu, 28 Sep 2017 06:30:35 GMT

Yes, this have been fixed in the SDK v14.0.0 release.

RE: Recursive calls to "app_sched_execute" in nRF Bootloader flow

sdaexpert — Thu, 28 Sep 2017 00:09:48 GMT

Hello, I have noticed that in the latest SDK release nRF5_SDK_14.0.0_3bcc1f7, the nrf_dfu_wait() function has been eliminated. Does it mean that "recursivity" problem (as described in the context of this thread) has been eliminated in that SDK version ?

RE: Recursive calls to "app_sched_execute" in nRF Bootloader flow

bjorn-spockeli — Fri, 28 Jul 2017 10:47:07 GMT

You are correct that the current usage of the Application Scheduler could lead to the the behavior you're describing. This has already been discovered internally and this will be fixed in the upcoming release of the SDK.

Unfortunately, I do not have a patch that can be applied to SDK v13.x.x, so my advice would be to wait until the next release which is expected very soon.

Best regards

Bjørn