Use locks to prevent race conditions in HCICordioTransport

[swnf]

Sometimes my BLE connections to my nrf52840 randomly stopped working. I've noticed that with BLE.debug(Serial) the HCI transport returned truncated packets in these situations. I suspect that this issue might be caused by concurrent access to the rx buffer in the cordio HCI transport. The Arduino core seems to use critical section locks while interacting with the ring buffers.

This MR introduces a lockForRead and unlockForRead method on the HCITransport to aquire a critical section lock. A Mutex might make more sense, but requires additional build flags and might not be available if handleRxData is called from an interrupt handler.

I've considered the following alternatives to the new methods:

• Just lock/unlock during read(). This naive approach works, but is very inefficient.
• Introduce a readBytes() method similar to Arduino's stream method which handles the lock/unlock. This approach is more difficult to implement because you don't know beforehand how large a packet is. You will still need multiple calls to readBytes() (including unnecessary lock/unlock calls).

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Project coverage is 15.25%. Comparing base (9263b3a) to head (b14172f).

Files with missing lines	Patch %	Lines
src/utility/HCI.cpp	0.00%	10 Missing ⚠️
src/utility/HCITransport.h	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #402      +/-   ##
==========================================
- Coverage   15.30%   15.25%   -0.05%     
==========================================
  Files          28       29       +1     
  Lines        3666     3678      +12     
==========================================
  Hits          561      561              
- Misses       3105     3117      +12     

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[github-actions]

Memory usage change @ b14172f

Board	flash	%	RAM for global variables	%
arduino:mbed_nano:nano33ble	🔺 +136 - +200	+0.01 - +0.02	0 - 0	0.0 - 0.0
arduino:mbed_nano:nanorp2040connect	🔺 +76 - +76	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:megaavr:uno2018:mode=on	🔺 +6 - +6	+0.01 - +0.01	0 - 0	0.0 - 0.0
arduino:renesas_uno:unor4wifi	🔺 +88 - +88	+0.03 - +0.03	0 - 0	0.0 - 0.0
arduino:samd:mkrwifi1010	🔺 +72 - +80	+0.03 - +0.03	0 - 0	0.0 - 0.0
arduino:samd:nano_33_iot	🔺 +72 - +80	+0.03 - +0.03	0 - 0	0.0 - 0.0

Click for full report table

Board	examples/Central/LedControl flash	%	examples/Central/LedControl RAM for global variables	%	examples/Central/PeripheralExplorer flash	%	examples/Central/PeripheralExplorer RAM for global variables	%	examples/Central/Scan flash	%	examples/Central/Scan RAM for global variables	%	examples/Central/ScanCallback flash	%	examples/Central/ScanCallback RAM for global variables	%	examples/Central/SensorTagButton flash	%	examples/Central/SensorTagButton RAM for global variables	%	examples/Peripheral/Advertising/EnhancedAdvertising flash	%	examples/Peripheral/Advertising/EnhancedAdvertising RAM for global variables	%	examples/Peripheral/Advertising/RawDataAdvertising flash	%	examples/Peripheral/Advertising/RawDataAdvertising RAM for global variables	%	examples/Peripheral/BatteryMonitor flash	%	examples/Peripheral/BatteryMonitor RAM for global variables	%	examples/Peripheral/ButtonLED flash	%	examples/Peripheral/ButtonLED RAM for global variables	%	examples/Peripheral/CallbackLED flash	%	examples/Peripheral/CallbackLED RAM for global variables	%	examples/Peripheral/EncryptedBatteryMonitor flash	%	examples/Peripheral/EncryptedBatteryMonitor RAM for global variables	%	examples/Peripheral/LED flash	%	examples/Peripheral/LED RAM for global variables	%
arduino:mbed_nano:nano33ble	136	0.01	0	0.0	200	0.02	0	0.0	200	0.02	0	0.0	136	0.01	0	0.0	136	0.01	0	0.0	136	0.01	0	0.0	200	0.02	0	0.0	136	0.01	0	0.0	136	0.01	0	0.0	136	0.01	0	0.0	136	0.01	0	0.0	136	0.01	0	0.0
arduino:mbed_nano:nanorp2040connect	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0	76	0.0	0	0.0
arduino:megaavr:uno2018:mode=on	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0	6	0.01	0	0.0
arduino:renesas_uno:unor4wifi	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0	88	0.03	0	0.0
arduino:samd:mkrwifi1010	72	0.03	0	0.0	80	0.03	0	0.0	80	0.03	0	0.0	80	0.03	0	0.0	72	0.03	0	0.0	80	0.03	0	0.0	72	0.03	0	0.0	72	0.03	0	0.0	72	0.03	0	0.0	72	0.03	0	0.0	80	0.03	0	0.0	80	0.03	0	0.0
arduino:samd:nano_33_iot	72	0.03	0	0.0	80	0.03	0	0.0	80	0.03	0	0.0	80	0.03	0	0.0	72	0.03	0	0.0	80	0.03	0	0.0	72	0.03	0	0.0	72	0.03	0	0.0	72	0.03	0	0.0	72	0.03	0	0.0	80	0.03	0	0.0	80	0.03	0	0.0

Click for full report CSV

Board,examples/Central/LedControl<br>flash,%,examples/Central/LedControl<br>RAM for global variables,%,examples/Central/PeripheralExplorer<br>flash,%,examples/Central/PeripheralExplorer<br>RAM for global variables,%,examples/Central/Scan<br>flash,%,examples/Central/Scan<br>RAM for global variables,%,examples/Central/ScanCallback<br>flash,%,examples/Central/ScanCallback<br>RAM for global variables,%,examples/Central/SensorTagButton<br>flash,%,examples/Central/SensorTagButton<br>RAM for global variables,%,examples/Peripheral/Advertising/EnhancedAdvertising<br>flash,%,examples/Peripheral/Advertising/EnhancedAdvertising<br>RAM for global variables,%,examples/Peripheral/Advertising/RawDataAdvertising<br>flash,%,examples/Peripheral/Advertising/RawDataAdvertising<br>RAM for global variables,%,examples/Peripheral/BatteryMonitor<br>flash,%,examples/Peripheral/BatteryMonitor<br>RAM for global variables,%,examples/Peripheral/ButtonLED<br>flash,%,examples/Peripheral/ButtonLED<br>RAM for global variables,%,examples/Peripheral/CallbackLED<br>flash,%,examples/Peripheral/CallbackLED<br>RAM for global variables,%,examples/Peripheral/EncryptedBatteryMonitor<br>flash,%,examples/Peripheral/EncryptedBatteryMonitor<br>RAM for global variables,%,examples/Peripheral/LED<br>flash,%,examples/Peripheral/LED<br>RAM for global variables,%
arduino:mbed_nano:nano33ble,136,0.01,0,0.0,200,0.02,0,0.0,200,0.02,0,0.0,136,0.01,0,0.0,136,0.01,0,0.0,136,0.01,0,0.0,200,0.02,0,0.0,136,0.01,0,0.0,136,0.01,0,0.0,136,0.01,0,0.0,136,0.01,0,0.0,136,0.01,0,0.0
arduino:mbed_nano:nanorp2040connect,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0,76,0.0,0,0.0
arduino:megaavr:uno2018:mode=on,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0,6,0.01,0,0.0
arduino:renesas_uno:unor4wifi,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0,88,0.03,0,0.0
arduino:samd:mkrwifi1010,72,0.03,0,0.0,80,0.03,0,0.0,80,0.03,0,0.0,80,0.03,0,0.0,72,0.03,0,0.0,80,0.03,0,0.0,72,0.03,0,0.0,72,0.03,0,0.0,72,0.03,0,0.0,72,0.03,0,0.0,80,0.03,0,0.0,80,0.03,0,0.0
arduino:samd:nano_33_iot,72,0.03,0,0.0,80,0.03,0,0.0,80,0.03,0,0.0,80,0.03,0,0.0,72,0.03,0,0.0,80,0.03,0,0.0,72,0.03,0,0.0,72,0.03,0,0.0,72,0.03,0,0.0,72,0.03,0,0.0,80,0.03,0,0.0,80,0.03,0,0.0

[facchinm]

LGTM! @gbr1 can you test this PR?

[gbr1]

Hi @swnf could you provide your test sketch? Thank you in advance

[swnf]

Hi @gbr1, I'm afraid I don't have any test sketch for this PR. I've tested this PR in a really large and complicated PlatformIO project and the issue only occurred randomly after multiple hours of data transmission. It's probably best if you just test any of the peripheral example sketches and make sure it is still working. I'm not aware of a way to trigger the issue.