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Message-Id: <20220412202613.234896-4-axboe@kernel.dk> Date: Tue, 12 Apr 2022 14:26:12 -0600 From: Jens Axboe <axboe@...nel.dk> To: io-uring@...r.kernel.org, netdev@...r.kernel.org Cc: Jens Axboe <axboe@...nel.dk> Subject: [PATCH 3/4] net: add support for socket no-lock If we have a guaranteed single user of a socket, then we can optimize the lock/release of it. Signed-off-by: Jens Axboe <axboe@...nel.dk> --- include/net/sock.h | 10 ++++++++-- net/core/sock.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 2 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 99fcc4d7eed9..aefc94677c94 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1674,7 +1674,7 @@ do { \ static inline bool lockdep_sock_is_held(const struct sock *sk) { - return lockdep_is_held(&sk->sk_lock) || + return sk->sk_no_lock || lockdep_is_held(&sk->sk_lock) || lockdep_is_held(&sk->sk_lock.slock); } @@ -1774,18 +1774,20 @@ static inline void unlock_sock_fast(struct sock *sk, bool slow) static inline void sock_owned_by_me(const struct sock *sk) { #ifdef CONFIG_LOCKDEP - WARN_ON_ONCE(!lockdep_sock_is_held(sk) && debug_locks); + WARN_ON_ONCE(!sk->sk_no_lock && !lockdep_sock_is_held(sk) && debug_locks); #endif } static inline bool sock_owned_by_user(const struct sock *sk) { sock_owned_by_me(sk); + smp_rmb(); return sk->sk_lock.owned; } static inline bool sock_owned_by_user_nocheck(const struct sock *sk) { + smp_rmb(); return sk->sk_lock.owned; } @@ -1794,6 +1796,10 @@ static inline void sock_release_ownership(struct sock *sk) if (sock_owned_by_user_nocheck(sk)) { sk->sk_lock.owned = 0; + if (sk->sk_no_lock) { + smp_wmb(); + return; + } /* The sk_lock has mutex_unlock() semantics: */ mutex_release(&sk->sk_lock.dep_map, _RET_IP_); } diff --git a/net/core/sock.c b/net/core/sock.c index fec892b384a4..d7eea29c5699 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2764,6 +2764,9 @@ void __lock_sock(struct sock *sk) { DEFINE_WAIT(wait); + if (WARN_ON_ONCE(sk->sk_no_lock)) + return; + for (;;) { prepare_to_wait_exclusive(&sk->sk_lock.wq, &wait, TASK_UNINTERRUPTIBLE); @@ -3307,8 +3310,21 @@ void sock_init_data(struct socket *sock, struct sock *sk) } EXPORT_SYMBOL(sock_init_data); +static inline bool lock_sock_nolock(struct sock *sk) +{ + if (sk->sk_no_lock) { + sk->sk_lock.owned = 1; + smp_wmb(); + return true; + } + return false; +} + void lock_sock_nested(struct sock *sk, int subclass) { + if (lock_sock_nolock(sk)) + return; + /* The sk_lock has mutex_lock() semantics here. */ mutex_acquire(&sk->sk_lock.dep_map, subclass, 0, _RET_IP_); @@ -3321,8 +3337,23 @@ void lock_sock_nested(struct sock *sk, int subclass) } EXPORT_SYMBOL(lock_sock_nested); +static inline bool release_sock_nolock(struct sock *sk) +{ + if (!sk->sk_no_lock) + return false; + if (READ_ONCE(sk->sk_backlog.tail)) + return false; + if (sk->sk_prot->release_cb) + sk->sk_prot->release_cb(sk); + sock_release_ownership(sk); + return true; +} + void release_sock(struct sock *sk) { + if (release_sock_nolock(sk)) + return; + spin_lock_bh(&sk->sk_lock.slock); if (sk->sk_backlog.tail) __release_sock(sk); -- 2.35.1
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