Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 2/4] rcu/nocb: Prepare to change nocb cpumask from CPU-hotplug protected cpuset caller | Date | Thu, 26 May 2022 00:10:53 +0200 |
| |
cpusets is going to use the NOCB (de-)offloading interface while holding hotplug lock. Therefore pull out the responsibility of protecting against concurrent CPU-hotplug changes to the callers of rcu_nocb_cpumask_update().
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Zefan Li <lizefan.x@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Phil Auld <pauld@redhat.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Waiman Long <longman@redhat.com> Cc: Daniel Bristot de Oliveira <bristot@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> --- kernel/rcu/rcutorture.c | 2 ++ kernel/rcu/tree_nocb.h | 4 ++-- 2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index f912ff4869b3..5a3029550e83 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1886,6 +1886,7 @@ static int rcu_nocb_toggle(void *arg) do { r = torture_random(&rand); cpu = (r >> 4) % (maxcpu + 1); + cpus_read_lock(); if (r & 0x1) { rcu_nocb_cpumask_update(cpumask_of(cpu), true); atomic_long_inc(&n_nocb_offload); @@ -1893,6 +1894,7 @@ static int rcu_nocb_toggle(void *arg) rcu_nocb_cpumask_update(cpumask_of(cpu), false); atomic_long_inc(&n_nocb_deoffload); } + cpus_read_unlock(); toggle_delay = torture_random(&rand) % toggle_fuzz + toggle_interval; set_current_state(TASK_INTERRUPTIBLE); schedule_hrtimeout(&toggle_delay, HRTIMER_MODE_REL); diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index 428571ad11e3..6396af6c765a 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -1182,12 +1182,13 @@ int rcu_nocb_cpumask_update(struct cpumask *cpumask, bool offload) int err_cpu; cpumask_var_t saved_nocb_mask; + lockdep_assert_cpus_held(); + if (!alloc_cpumask_var(&saved_nocb_mask, GFP_KERNEL)) return -ENOMEM; cpumask_copy(saved_nocb_mask, rcu_nocb_mask); - cpus_read_lock(); mutex_lock(&rcu_state.barrier_mutex); for_each_cpu(cpu, cpumask) { if (offload) { @@ -1221,7 +1222,6 @@ int rcu_nocb_cpumask_update(struct cpumask *cpumask, bool offload) } mutex_unlock(&rcu_state.barrier_mutex); - cpus_read_unlock(); free_cpumask_var(saved_nocb_mask); -- 2.25.1
| |