----- On Jul 13, 2020, at 9:47 AM, Nicholas Piggin npiggin@xxxxxxxxx wrote: > Excerpts from Nicholas Piggin's message of July 13, 2020 2:45 pm: >> Excerpts from Andy Lutomirski's message of July 11, 2020 3:04 am: >>> Also, as it stands, I can easily see in_irq() ceasing to promise to >>> serialize. There are older kernels for which it does not promise to >>> serialize. And I have plans to make it stop serializing in the >>> nearish future. >> >> You mean x86's return from interrupt? Sounds fun... you'll konw where to >> update the membarrier sync code, at least :) > > Oh, I should actually say Mathieu recently clarified a return from > interrupt doesn't fundamentally need to serialize in order to support > membarrier sync core. Clarification to your statement: Return from interrupt to kernel code does not need to be context serializing as long as kernel serializes before returning to user-space. However, return from interrupt to user-space needs to be context serializing. Thanks, Mathieu > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-July/214171.html > > So you may not need to do anything more if you relaxed it. > > Thanks, > Nick -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
