From b3483bc7a1f2673b35331e60668104ba2be46510 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 25 Feb 2022 08:18:55 -0800 Subject: [PATCH] net/sysctl: avoid two synchronize_rcu() calls Both rps_sock_flow_sysctl() and flow_limit_cpu_sysctl() are using synchronize_rcu() right before freeing memory either by vfree() or kfree() They can switch to kvfree_rcu(ptr) and kfree_rcu(ptr) to benefit from asynchronous mode, instead of blocking the current thread. Note that kvfree_rcu(ptr) and kfree_rcu(ptr) eventually can have to use synchronize_rcu() in some memory pressure cases. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/sysctl_net_core.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index dbeb8ec..7123fe7 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -103,8 +103,7 @@ static int rps_sock_flow_sysctl(struct ctl_table *table, int write, if (orig_sock_table) { static_branch_dec(&rps_needed); static_branch_dec(&rfs_needed); - synchronize_rcu(); - vfree(orig_sock_table); + kvfree_rcu(orig_sock_table); } } } @@ -142,8 +141,7 @@ static int flow_limit_cpu_sysctl(struct ctl_table *table, int write, lockdep_is_held(&flow_limit_update_mutex)); if (cur && !cpumask_test_cpu(i, mask)) { RCU_INIT_POINTER(sd->flow_limit, NULL); - synchronize_rcu(); - kfree(cur); + kfree_rcu(cur); } else if (!cur && cpumask_test_cpu(i, mask)) { cur = kzalloc_node(len, GFP_KERNEL, cpu_to_node(i)); -- 2.7.4