[PATCH net-next 1/6] mptcp: open code mptcp variant for lock_sock

[Paolo Abeni]

This allows invoking an additional callback under the
socket spin lock.

Will be used by the next patches to avoid additional
spin lock contention.

Acked-by: Florian Westphal <f...@strlen.de>
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
 include/net/sock.h   |  1 +
 net/core/sock.c      |  2 +-
 net/mptcp/protocol.h | 13 +++++++++++++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 80469c2c448d..f59764614e30 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1590,6 +1590,7 @@ static inline void lock_sock(struct sock *sk)
        lock_sock_nested(sk, 0);
 }
 
+void __lock_sock(struct sock *sk);
 void __release_sock(struct sock *sk);
 void release_sock(struct sock *sk);
 
diff --git a/net/core/sock.c b/net/core/sock.c
index 9badbe7bb4e4..f0f096852876 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2486,7 +2486,7 @@ bool sk_page_frag_refill(struct sock *sk, struct 
page_frag *pfrag)
 }
 EXPORT_SYMBOL(sk_page_frag_refill);
 
-static void __lock_sock(struct sock *sk)
+void __lock_sock(struct sock *sk)
        __releases(&sk->sk_lock.slock)
        __acquires(&sk->sk_lock.slock)
 {
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 82d5626323b1..6abac8238de3 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -253,6 +253,19 @@ struct mptcp_sock {
        } rcvq_space;
 };
 
+#define mptcp_lock_sock(___sk, cb) do {                                        
\
+       struct sock *__sk = (___sk); /* silence macro reuse warning */  \
+       might_sleep();                                                  \
+       spin_lock_bh(&__sk->sk_lock.slock);                             \
+       if (__sk->sk_lock.owned)                                        \
+               __lock_sock(__sk);                                      \
+       cb;                                                             \
+       __sk->sk_lock.owned = 1;                                        \
+       spin_unlock(&__sk->sk_lock.slock);                              \
+       mutex_acquire(&__sk->sk_lock.dep_map, 0, 0, _RET_IP_);          \
+       local_bh_enable();                                              \
+} while (0)
+
 #define mptcp_for_each_subflow(__msk, __subflow)                       \
        list_for_each_entry(__subflow, &((__msk)->conn_list), node)
 
-- 
2.26.2