On Wed, 2005-03-23 at 08:16 +0100, Ingo Molnar wrote: > * Ingo Molnar <[EMAIL PROTECTED]> wrote: > > > That callback will be queued on CPU#2 - while the task still keeps > > current->rcu_data of CPU#1. It also means that CPU#2's read counter > > did _not_ get increased - and a too short grace period may occur. > > > > it seems to me that that only safe method is to pick an 'RCU CPU' when > > first entering the read section, and then sticking to it, no matter > > where the task gets migrated to. Or to 'migrate' the +1 read count > > from one CPU to the other, within the scheduler. > > i think the 'migrate read-count' method is not adequate either, because > all callbacks queued within an RCU read section must be called after the > lock has been dropped - while with the migration method CPU#1 would be > free to process callbacks queued in the RCU read section still active on > CPU#2. > how about keeping the rcu callback list in process context and only splice it to a global (per cpu) list on rcu_read_unlock?
Kind regrads, Peter Zijlstra -- Peter Zijlstra <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
