[PATCH v2] net: core: annotate socks of struct sock_reuseport with __counted_by

[Dmitry Antipov]

According to '__reuseport_alloc()', annotate flexible array member
'sock' of 'struct sock_reuseport' with '__counted_by()' and use
convenient 'struct_size()' to simplify the math used in 'kzalloc()'.

Signed-off-by: Dmitry Antipov <dmanti...@yandex.ru>
---
v2: style (Jakub), title and commit message (Gustavo) adjustments
---
 include/net/sock_reuseport.h | 2 +-
 net/core/sock_reuseport.c    | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/net/sock_reuseport.h b/include/net/sock_reuseport.h
index 6ec140b0a61b..6e4faf3ee76f 100644
--- a/include/net/sock_reuseport.h
+++ b/include/net/sock_reuseport.h
@@ -26,7 +26,7 @@ struct sock_reuseport {
        unsigned int            bind_inany:1;
        unsigned int            has_conns:1;
        struct bpf_prog __rcu   *prog;          /* optional BPF sock selector */
-       struct sock             *socks[];       /* array of sock pointers */
+       struct sock             *socks[] __counted_by(max_socks);
 };
 
 extern int reuseport_alloc(struct sock *sk, bool bind_inany);
diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
index 5a165286e4d8..79f2456e27a5 100644
--- a/net/core/sock_reuseport.c
+++ b/net/core/sock_reuseport.c
@@ -173,9 +173,9 @@ static bool __reuseport_detach_closed_sock(struct sock *sk,
 
 static struct sock_reuseport *__reuseport_alloc(unsigned int max_socks)
 {
-       unsigned int size = sizeof(struct sock_reuseport) +
-                     sizeof(struct sock *) * max_socks;
-       struct sock_reuseport *reuse = kzalloc(size, GFP_ATOMIC);
+       struct sock_reuseport *reuse;
+
+       reuse = kzalloc(struct_size(reuse, socks, max_socks), GFP_ATOMIC);
 
        if (!reuse)
                return NULL;
-- 
2.45.2