On Sat, Apr 15, 2023 at 11:46 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > On Sat, 15 Apr 2023 22:33:17 +0800 > Yafang Shao <laoar.shao@xxxxxxxxx> wrote: > > > > > I don't have a clear idea why TRACE_CTX_TRANSITION must be needed, but > > it seems we have to do below code for the fentry test case, > > The issue is that there's still cases that we can trace when > preempt_count hasn't been updated to the new context. That is, > preempt_count is used to determine if we are in softirq, hardirq or NMI > context. But there's some places that have: > > normal context: > func_a() --> traced > --> interrupt > func_b() --> traced > preempt_count_add(HARDIRQ_OFFSET) > > Now we drop the second trace because it is flagged as a recursion when > in reality it is in a new context, but the preempt_count has not been > updated yet. > > We are currently fixing these locations, but it's not there yet. And > since there's tools that relies on not dropping these locations, the > transition bit needs to be there until this situation is dealt with. > Got it. Thanks for your explanation. > Can you change the tests to allow a single recursion? > I think one single recursion should be acceptable. I will change it. -- Regards Yafang
