Messages in this thread | | | Date | Sun, 23 Sep 2018 16:55:12 -0700 | From | "Paul E. McKenney" <> | Subject | Re: Question about ->head field of rcu_segcblist |
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On Sun, Sep 23, 2018 at 07:31:37PM -0400, Joel Fernandes wrote: > On Sun, Sep 23, 2018 at 7:30 PM Joel Fernandes <joel@joelfernandes.org> wrote: > > > > Hi Paul, > > > > I was parsing the Data-Structures document and had a question about > > the following "Important note" text. > > > > Could it be clarified in the below text better why "remaining > > callbacks are placed back on the RCU_DONE_TAIL segment", is a reason > > for not depending on ->head for determining if no callbacks are > > associated with the rcu_segcblist? If callbacks are added back to the > > DONE_TAIL segment, then I would think rcu_head should be != NULL. > > Infact the "rsclp->head = *rsclp->tails[RCU_DONE_TAIL];" in > > rcu_segcblist_extract_done_cbs should set the ->head to NULL if I > > understand correctly. > > Just to clarify, I meant set to NULL assuming all cbs were done > waiting and ready to be invoked.
Ah, good, then that is correct. But even then, being NULL doesn't mean no callbacks because they might be temporarily held by rcu_do_batch().
Thanx, Paul
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