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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-06-11 21:50:22 (GMT) |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-07-17 21:58:42 (GMT) |
| commit | 9b683874504a57cfa97558d403c75e286e20c9ce (patch) | |
| tree | 7feefb3d2a33e5bf0a6ff9b96c06fdf5db215eba /kernel/rcu | |
| parent | 13bd64947f53ba8d7199922be94b6626b8e222d7 (diff) | |
| download | linux-9b683874504a57cfa97558d403c75e286e20c9ce.tar.xz | |
rcu: Stop disabling CPU hotplug in synchronize_rcu_expedited()
The fact that tasks could be migrated from leaf to root rcu_node
structures meant that synchronize_rcu_expedited() had to disable
CPU hotplug. However, tasks now stay put, so this commit removes the
CPU-hotplug disabling from synchronize_rcu_expedited().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 25 |
1 files changed, 2 insertions, 23 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 5dac0a1..7234f03 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -728,42 +728,23 @@ void synchronize_rcu_expedited(void) smp_mb(); /* Above access cannot bleed into critical section. */ /* - * Block CPU-hotplug operations. This means that any CPU-hotplug - * operation that finds an rcu_node structure with tasks in the - * process of being boosted will know that all tasks blocking - * this expedited grace period will already be in the process of - * being boosted. This simplifies the process of moving tasks - * from leaf to root rcu_node structures. - */ - if (!try_get_online_cpus()) { - /* CPU-hotplug operation in flight, fall back to normal GP. */ - wait_rcu_gp(call_rcu); - return; - } - - /* * Acquire lock, falling back to synchronize_rcu() if too many * lock-acquisition failures. Of course, if someone does the * expedited grace period for us, just leave. */ while (!mutex_trylock(&sync_rcu_preempt_exp_mutex)) { if (ULONG_CMP_LT(snap, - READ_ONCE(sync_rcu_preempt_exp_count))) { - put_online_cpus(); + READ_ONCE(sync_rcu_preempt_exp_count))) goto mb_ret; /* Others did our work for us. */ - } if (trycount++ < 10) { udelay(trycount * num_online_cpus()); } else { - put_online_cpus(); wait_rcu_gp(call_rcu); return; } } - if (ULONG_CMP_LT(snap, READ_ONCE(sync_rcu_preempt_exp_count))) { - put_online_cpus(); + if (ULONG_CMP_LT(snap, READ_ONCE(sync_rcu_preempt_exp_count))) goto unlock_mb_ret; /* Others did our work for us. */ - } /* force all RCU readers onto ->blkd_tasks lists. */ synchronize_sched_expedited(); @@ -779,8 +760,6 @@ void synchronize_rcu_expedited(void) rcu_for_each_leaf_node(rsp, rnp) sync_rcu_preempt_exp_init2(rsp, rnp); - put_online_cpus(); - /* Wait for snapshotted ->blkd_tasks lists to drain. */ rnp = rcu_get_root(rsp); wait_event(sync_rcu_preempt_exp_wq, |