net: add SK_WMEM_ALLOC_BIAS constant

sk->sk_wmem_alloc is initialized to 1, and sk_wmem_alloc_get()
takes care of this initial value.

Add SK_WMEM_ALLOC_BIAS define to not spread this magic value.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20251013152234.842065-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/sock.h b/include/net/sock.h
index 60bcb13f045c3144609908a36960528b33e4f71c..2794bc5c565424491a064049d3d76c3fb7ba1ed8 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2303,6 +2303,7 @@ static inline int skb_copy_to_page_nocache(struct sock *sk, struct iov_iter *fro
        return 0;
 }
 
+#define SK_WMEM_ALLOC_BIAS 1
 /**
  * sk_wmem_alloc_get - returns write allocations
  * @sk: socket
@@ -2311,7 +2312,7 @@ static inline int skb_copy_to_page_nocache(struct sock *sk, struct iov_iter *fro
  */
 static inline int sk_wmem_alloc_get(const struct sock *sk)
 {
-       return refcount_read(&sk->sk_wmem_alloc) - 1;
+       return refcount_read(&sk->sk_wmem_alloc) - SK_WMEM_ALLOC_BIAS;
 }
 
 /**

diff --git a/net/atm/common.c b/net/atm/common.c
index 881c7f259dbd46be35d71e558a73eb2f26223963..cecc71a8bee1176518a2d63b4613dbd243543695 100644 (file)
--- a/net/atm/common.c
+++ b/net/atm/common.c
@@ -157,7 +157,7 @@ int vcc_create(struct net *net, struct socket *sock, int protocol, int family, i
        memset(&vcc->local, 0, sizeof(struct sockaddr_atmsvc));
        memset(&vcc->remote, 0, sizeof(struct sockaddr_atmsvc));
        vcc->qos.txtp.max_sdu = 1 << 16; /* for meta VCs */
-       refcount_set(&sk->sk_wmem_alloc, 1);
+       refcount_set(&sk->sk_wmem_alloc, SK_WMEM_ALLOC_BIAS);
        atomic_set(&sk->sk_rmem_alloc, 0);
        vcc->push = NULL;
        vcc->pop = NULL;

diff --git a/net/core/sock.c b/net/core/sock.c
index dc03d4b5909a2a68aee84eb9a153b2c3970f6b32..542cfa16ee125f6c8487237c9040695d42794087 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2313,7 +2313,7 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
                }
 
                sock_net_set(sk, net);
-               refcount_set(&sk->sk_wmem_alloc, 1);
+               refcount_set(&sk->sk_wmem_alloc, SK_WMEM_ALLOC_BIAS);
 
                mem_cgroup_sk_alloc(sk);
                cgroup_sk_alloc(&sk->sk_cgrp_data);
@@ -2494,8 +2494,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 
        atomic_set(&newsk->sk_rmem_alloc, 0);
 
-       /* sk_wmem_alloc set to one (see sk_free() and sock_wfree()) */
-       refcount_set(&newsk->sk_wmem_alloc, 1);
+       refcount_set(&newsk->sk_wmem_alloc, SK_WMEM_ALLOC_BIAS);
 
        atomic_set(&newsk->sk_omem_alloc, 0);
        sk_init_common(newsk);