Protect G_freeUsrBufList context switches / SMP
Internal PRs: MAIN_PR006856 MDIS5 for Linux multithreading issue in MDIS Kernel MAIN_PR006854 F75P IOP - F215 frequently lose frame in multi-thread receive mode
This problem was observed with the MSCAN driver (https://github.com/MEN-Mikro-Elektronik/13Z015-06) but can probably be reproduce with any other driver.
I will create a corresponding issue.