On Fri 2020-10-30 10:48:58, Miroslav Benes wrote: > > > > > + bit = ftrace_test_recursion_trylock(); > > > > > + if (bit < 0) > > > > > + return; > > > > > > > > This means that the original function will be called in case of recursion. > > > > That's probably fair, but I'm wondering if we should at least WARN about > > > > it. > > > > > > Yeah, the early return might break the consistency model and > > > unexpected things might happen. We should be aware of it. > > > Please use: > > > > > > if (WARN_ON_ONCE(bit < 0)) > > > return; > > > > > > WARN_ON_ONCE() might be part of the recursion. But it should happen > > > only once. IMHO, it is worth the risk. > > > > > > Otherwise it looks good. > > > > Perhaps we can add that as a separate patch, because this patch doesn't add > > any real functionality change. It only moves the recursion testing from the > > helper function (which ftrace wraps all callbacks that do not have the > > RECURSION flags set, including this one) down to your callback. > > > > In keeping with one patch to do one thing principle, the added of > > WARN_ON_ONCE() should be a separate patch, as that will change the > > functionality. > > > > If that WARN_ON_ONCE() breaks things, I'd like it to be bisected to another > > patch other than this one. > > Works for me. +1 So, with the updated commit message: Reviewed-by: Petr Mladek <pmladek@xxxxxxxx> Best Regards, Petr
