On Tue, Jan 16, 2007 at 12:54:46AM +0530, Dipankar Sarma wrote: > > > Fix rcu_barrier() to work properly in preemptive kernel environment. > Also, the ordering of callback must be preserved while moving > callbacks to another CPU during CPU hotplug.
Acked-by: Paul E. McKenney <[EMAIL PROTECTED]> > Signed-off-by: Dipankar Sarma <[EMAIL PROTECTED]> > --- > > > > diff -puN kernel/rcuclassic.c~rcu-fix-barriers kernel/rcuclassic.c > --- linux-2.6.20-rc3-mm1-rcu/kernel/rcuclassic.c~rcu-fix-barriers > 2007-01-15 15:36:47.000000000 +0530 > +++ linux-2.6.20-rc3-mm1-rcu-dipankar/kernel/rcuclassic.c 2007-01-15 > 15:36:47.000000000 +0530 > @@ -350,9 +350,9 @@ static void __rcu_offline_cpu(struct rcu > if (rcp->cur != rcp->completed) > cpu_quiet(rdp->cpu, rcp); > spin_unlock_bh(&rcp->lock); > + rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail); > rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail); > rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail); > - rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail); > } > > static void rcu_offline_cpu(int cpu) > diff -puN kernel/rcupdate.c~rcu-fix-barriers kernel/rcupdate.c > --- linux-2.6.20-rc3-mm1-rcu/kernel/rcupdate.c~rcu-fix-barriers > 2007-01-15 15:36:47.000000000 +0530 > +++ linux-2.6.20-rc3-mm1-rcu-dipankar/kernel/rcupdate.c 2007-01-15 > 15:36:47.000000000 +0530 > @@ -117,7 +117,18 @@ void rcu_barrier(void) > mutex_lock(&rcu_barrier_mutex); > init_completion(&rcu_barrier_completion); > atomic_set(&rcu_barrier_cpu_count, 0); > + /* > + * The queueing of callbacks in all CPUs must be > + * atomic with respect to RCU, otherwise one cpu may > + * queue a callback, wait for a grace period, decrement > + * barrier count and call complete(), while other CPUs > + * haven't yet queued anything. So, we need to make sure > + * that no grace period happens until all the callbacks > + * are queued. > + */ > + rcu_read_lock(); > on_each_cpu(rcu_barrier_func, NULL, 0, 1); > + rcu_read_unlock(); > wait_for_completion(&rcu_barrier_completion); > mutex_unlock(&rcu_barrier_mutex); > } > > _ - 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/
