On Mon, Sep 14, 2020 at 07:55:18AM +0000, Zhang, Qiang wrote: > Hello Paul > > I have some questions for you . > in force_qs_rnp func , if "f(rdp)" func return true we will call > rcu_report_qs_rnp func > report a quiescent state for this rnp node, and clear grpmask form > rnp->qsmask. > after that , can we make a check for this rnp->qsmask, if rnp->qsmask == > 0, > we will check blocked readers in this rnp node, instead of jumping directly > to the next node .
Could you clarify what good is this going to do? What problem are you trying to address? You could have a task that is blocked in an RCU leaf node, but the force_qs_rnp() decided to call rcu_report_qs_rnp(). This is perfectly Ok. The CPU could be dyntick-idle and a quiescent state is reported. However, the GP must not end and the rcu leaf node should still be present in its parent intermediate nodes ->qsmask. In this case, the ->qsmask == 0 does not have any relevance. Or am I missing the point of the question? thanks, - Joel
