diff options
| author | Uladzislau Rezki (Sony) <urezki@gmail.com> | 2022-11-29 18:58:21 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2023-01-04 04:48:41 +0300 |
| commit | 8fc5494ad5face62747a3937db66b00db1e5d80b (patch) | |
| tree | db67cb2fdc0efa66885c3c7dad99ba8a2e5a8a11 /kernel/rcu | |
| parent | 8c15a9e8086508962b2b69456ed22dc517d91b15 (diff) | |
| download | linux-8fc5494ad5face62747a3937db66b00db1e5d80b.tar.xz | |
rcu/kvfree: Move need_offload_krc() out of krcp->lock
The need_offload_krc() function currently holds the krcp->lock in order
to safely check krcp->head. This commit removes the need for this lock
in that function by updating the krcp->head pointer using WRITE_ONCE()
macro so that readers can carry out lockless loads of that pointer.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 839e617f6c37..0c42fce4efe3 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3194,7 +3194,7 @@ static void kfree_rcu_monitor(struct work_struct *work) // objects queued on the linked list. if (!krwp->head_free) { krwp->head_free = krcp->head; - krcp->head = NULL; + WRITE_ONCE(krcp->head, NULL); } WRITE_ONCE(krcp->count, 0); @@ -3208,6 +3208,8 @@ static void kfree_rcu_monitor(struct work_struct *work) } } + raw_spin_unlock_irqrestore(&krcp->lock, flags); + // If there is nothing to detach, it means that our job is // successfully done here. In case of having at least one // of the channels that is still busy we should rearm the @@ -3215,8 +3217,6 @@ static void kfree_rcu_monitor(struct work_struct *work) // still in progress. if (need_offload_krc(krcp)) schedule_delayed_monitor_work(krcp); - - raw_spin_unlock_irqrestore(&krcp->lock, flags); } static enum hrtimer_restart @@ -3386,7 +3386,7 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr) head->func = ptr; head->next = krcp->head; - krcp->head = head; + WRITE_ONCE(krcp->head, head); success = true; } @@ -3463,15 +3463,12 @@ static struct shrinker kfree_rcu_shrinker = { void __init kfree_rcu_scheduler_running(void) { int cpu; - unsigned long flags; for_each_possible_cpu(cpu) { struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); - raw_spin_lock_irqsave(&krcp->lock, flags); if (need_offload_krc(krcp)) schedule_delayed_monitor_work(krcp); - raw_spin_unlock_irqrestore(&krcp->lock, flags); } } |