* Ingo Molnar <[EMAIL PROTECTED]> wrote: > hm, another thing: i think call_rcu() needs to take the read-lock. > Right now it assumes that it has the data structure private, but > that's only statistically true on PREEMPT_RT: another CPU may have > this CPU's RCU control structure in use. So IRQs-off (or preempt-off) > is not a guarantee to have the data structure, the read lock has to be > taken.
i've reworked the code to use the read-lock to access the per-CPU data RCU structures, and it boots with 2 CPUs and PREEMPT_RT now. The -40-05 patch can be downloaded from the usual place: http://redhat.com/~mingo/realtime-preempt/ had to add two hacks though: static void rcu_advance_callbacks(struct rcu_data *rdp) { if (rdp->batch != rcu_ctrlblk.batch) { if (rdp->donetail) // HACK *rdp->donetail = rdp->waitlist; ... void fastcall call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) [...] rcu_advance_callbacks(rdp); if (rdp->waittail) // HACK *rdp->waittail = head; ... without them it crashes during bootup. maybe we are better off with the completely unlocked read path and the long grace periods. Ingo - 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/
