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| author | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-04-16 14:09:15 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-08-13 14:35:49 -0700 |
| commit | c00045be32fe13333ba8c62748ba04747c182838 (patch) | |
| tree | f62d6a3588c76d30d16e9f720fa30c5d8f4106ea /kernel/rcu | |
| parent | 750d7f6a434ff4640fa825dfb1eccb44e79fb6af (diff) | |
| download | linux-c00045be32fe13333ba8c62748ba04747c182838.tar.bz2 | |
rcu/nocb: Make rcutree_migrate_callbacks() start at leaf rcu_node structure
Because rcutree_migrate_callbacks() is invoked infrequently and because
an exact snapshot of the grace-period state might save some callbacks a
second trip through a grace period, this function has used the root
rcu_node structure. However, this safe-second-trip optimization
happens only if rcutree_migrate_callbacks() races with grace-period
initialization, so it is not worth the added mental load. This commit
therefore makes rcutree_migrate_callbacks() start with the leaf rcu_node
structures, as is done elsewhere.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 969ba292a669..ea479d81da7f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3157,8 +3157,8 @@ void rcutree_migrate_callbacks(int cpu) { unsigned long flags; struct rcu_data *my_rdp; + struct rcu_node *my_rnp; struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); - struct rcu_node *rnp_root = rcu_get_root(); bool needwake; if (rcu_segcblist_is_offloaded(&rdp->cblist) || @@ -3167,18 +3167,19 @@ void rcutree_migrate_callbacks(int cpu) local_irq_save(flags); my_rdp = this_cpu_ptr(&rcu_data); + my_rnp = my_rdp->mynode; if (rcu_nocb_adopt_orphan_cbs(my_rdp, rdp, flags)) { local_irq_restore(flags); return; } - raw_spin_lock_rcu_node(rnp_root); /* irqs already disabled. */ + raw_spin_lock_rcu_node(my_rnp); /* irqs already disabled. */ /* Leverage recent GPs and set GP for new callbacks. */ - needwake = rcu_advance_cbs(rnp_root, rdp) || - rcu_advance_cbs(rnp_root, my_rdp); + needwake = rcu_advance_cbs(my_rnp, rdp) || + rcu_advance_cbs(my_rnp, my_rdp); rcu_segcblist_merge(&my_rdp->cblist, &rdp->cblist); WARN_ON_ONCE(rcu_segcblist_empty(&my_rdp->cblist) != !rcu_segcblist_n_cbs(&my_rdp->cblist)); - raw_spin_unlock_irqrestore_rcu_node(rnp_root, flags); + raw_spin_unlock_irqrestore_rcu_node(my_rnp, flags); if (needwake) rcu_gp_kthread_wake(); WARN_ONCE(rcu_segcblist_n_cbs(&rdp->cblist) != 0 || |