[ Please avoid top-posting. ] On Thu, Apr 15, 2021 at 07:09:14PM +0200, Erwan LE RAY wrote: > Hi Dillon, > > STM32MP151 is mono-core, but both STM32MP153 and STM32MP157 are > dual-core (see > https://www.st.com/content/st_com/en/products/microcontrollers-microprocessors/stm32-arm-cortex-mpus.html). > So your point is fully relevant, thanks. > > ST already fixed the same issue in st-asc.c driver in the past (see > ef49ffd8), because a systematic deadlock was detected with RT kernel. That's not the same issue. The above mentioned commit fixed an issue on *RT* where local_irq_save() should be avoided. > You proposed a first implementation in your patch, and a second one in > the discussion. It seems that your initial proposal (ie your V2 patch) > is the most standard one (implemented in 6 drivers). The second > implementation is implemented by only 1 company. > > It looks that the solution is to avoid locking in the sysrq case and > trylock in the oops_in_progress case (see detailed analysis in > 677fe555cbfb1). > > So your initial patch looks to the right proposal, but it would be safer > if Greg could confirm it. That would only fix the RT issue (and by making the sysrq one slightly worse). Using uart_unlock_and_check_sysrq() would address both issues. Johan
