udp: make busylock per socket

While having all spinlocks packed into an array was a space saver,
this also caused NUMA imbalance and hash collisions.

UDPv6 socket size becomes 1600 after this patch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250916160951.541279-10-edumazet@google.com
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 6ed008ab166557e868c1918daaaa5d551b7989a7..e554890c4415b411f35007d3ece9e6042db7a544 100644 (file)
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -109,6 +109,7 @@ struct udp_sock {
         */
        struct hlist_node       tunnel_list;
        struct numa_drop_counters drop_counters;
+       spinlock_t              busylock ____cacheline_aligned_in_smp;
 };
 
 #define udp_test_bit(nr, sk)                   \

diff --git a/include/net/udp.h b/include/net/udp.h
index a08822e294b038c0d00d4a5f5cac62286a207926..eecd64097f91196897f45530540b9c9b68c5ba4e 100644 (file)
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -289,6 +289,7 @@ static inline void udp_lib_init_sock(struct sock *sk)
        struct udp_sock *up = udp_sk(sk);
 
        sk->sk_drop_counters = &up->drop_counters;
+       spin_lock_init(&up->busylock);
        skb_queue_head_init(&up->reader_queue);
        INIT_HLIST_NODE(&up->tunnel_list);
        up->forward_threshold = sk->sk_rcvbuf >> 2;

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 25143f932447df2a84dd113ca33e1ccf15b3503c..7d1444821ee51a19cd5fd0dd5b8d096104c9283c 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1689,17 +1689,11 @@ static void udp_skb_dtor_locked(struct sock *sk, struct sk_buff *skb)
  * to relieve pressure on the receive_queue spinlock shared by consumer.
  * Under flood, this means that only one producer can be in line
  * trying to acquire the receive_queue spinlock.
- * These busylock can be allocated on a per cpu manner, instead of a
- * per socket one (that would consume a cache line per socket)
  */
-static int udp_busylocks_log __read_mostly;
-static spinlock_t *udp_busylocks __read_mostly;
-
-static spinlock_t *busylock_acquire(void *ptr)
+static spinlock_t *busylock_acquire(struct sock *sk)
 {
-       spinlock_t *busy;
+       spinlock_t *busy = &udp_sk(sk)->busylock;
 
-       busy = udp_busylocks + hash_ptr(ptr, udp_busylocks_log);
        spin_lock(busy);
        return busy;
 }
@@ -3997,7 +3991,6 @@ static void __init bpf_iter_register(void)
 void __init udp_init(void)
 {
        unsigned long limit;
-       unsigned int i;
 
        udp_table_init(&udp_table, "UDP");
        limit = nr_free_buffer_pages() / 8;
@@ -4006,15 +3999,6 @@ void __init udp_init(void)
        sysctl_udp_mem[1] = limit;
        sysctl_udp_mem[2] = sysctl_udp_mem[0] * 2;
 
-       /* 16 spinlocks per cpu */
-       udp_busylocks_log = ilog2(nr_cpu_ids) + 4;
-       udp_busylocks = kmalloc(sizeof(spinlock_t) << udp_busylocks_log,
-                               GFP_KERNEL);
-       if (!udp_busylocks)
-               panic("UDP: failed to alloc udp_busylocks\n");
-       for (i = 0; i < (1U << udp_busylocks_log); i++)
-               spin_lock_init(udp_busylocks + i);
-
        if (register_pernet_subsys(&udp_sysctl_ops))
                panic("UDP: failed to init sysctl parameters.\n");