On Sun, Nov 10, 2019 at 01:10:39PM -0800, Linus Torvalds wrote: > On Sun, Nov 10, 2019 at 12:44 PM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote: > > > > But will "one size fits all" be practical and useful? > > Oh, I do agree that if KCSAN has some mode where it says "I'll ignore > repeated writes with the same value" (or whatever), it could/should > likely be behind some flag. > > I don't think it should be a subsystem flag, though. More of a "I'm > willing to actually analyze and ignore false positives" flag. Because > I don't think it's so much about the code, as it is about the person > who looks at the results. > > For example, we're already getting push-back from people on some of > the KCSAN-inspired patches. If we have people sending patches to add > READ_ONCE/WRITE_ONCE to random places to shut up KCSAN reports, I > don't think that's good. > > But if we have people who _work_ on memory ordering issues etc, and > want to see a strict mode, knowing there are false positives and able > to handle them, that's a completely different thing.. > > No? Understood on the pushback! And I especially agree that it is bad to automatically add *_ONCE() just to shut up KCSAN. For one thing, doing that inconveniences people later on who might want to take a closer look. As long as I can get the full-up reports for RCU. And as long as the others who want the full-up reports can also get them. ;-) And agreed, if the results are adjusted based on who is processing them, that should be good. Thanx, Paul
