tcp: fix lockdep splat in tcp_snd_una_update()

tcp_snd_una_update() and tcp_rcv_nxt_update() call
u64_stats_update_begin() either from process context or BH handler.

This triggers a lockdep splat on 32bit & SMP builds.

We could add u64_stats_update_begin_bh() variant but this would
slow down 32bit builds with useless local_disable_bh() and
local_enable_bh() pairs, since we own the socket lock at this point.

I add sock_owned_by_me() helper to have proper lockdep support
even on 64bit builds, and new u64_stats_update_begin_raw()
and u64_stats_update_end_raw methods.

Fixes: c10d9310edf5 ("tcp: do not assume TCP code is non preemptible")
Reported-by: Fabio Estevam <festevam@gmail.com>
Diagnosed-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 1 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 45f5b492c658..c9c8b19df27c 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1421,11 +1421,16 @@ static inline void unlock_sock_fast(struct sock *sk, bool slow)
  * accesses from user process context.
  */
 
-static inline bool sock_owned_by_user(const struct sock *sk)
+static inline void sock_owned_by_me(const struct sock *sk)
 {
 #ifdef CONFIG_LOCKDEP
         WARN_ON_ONCE(!lockdep_sock_is_held(sk) && debug_locks);
 #endif
+}
+
+static inline bool sock_owned_by_user(const struct sock *sk)
+{
+        sock_owned_by_me(sk);
         return sk->sk_lock.owned;
 }