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| author |   Pavel Begunkov <asml.silence@gmail.com> | 2022-04-28 11:58:18 +0100 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2022-05-01 12:19:01 +0100 |
| commit | 052ada096842a910327936b4ed203048906eb2c3 (patch) | |
| tree | 531ce98d0886f25915c1be699660ad04a0bfd31f /net/core/sock.c | |
| parent | sock: dedup sock_def_write_space wmem_alloc checks (diff) | |
| download | linux-dev-052ada096842a910327936b4ed203048906eb2c3.tar.xz linux-dev-052ada096842a910327936b4ed203048906eb2c3.zip | |
sock: optimise UDP sock_wfree() refcounting
For non SOCK_USE_WRITE_QUEUE sockets, sock_wfree() (atomically) puts
->sk_wmem_alloc twice. It's needed to keep the socket alive while
calling ->sk_write_space() after the first put.
However, some sockets, such as UDP, are freed by RCU
(i.e. SOCK_RCU_FREE) and use already RCU-safe sock_def_write_space().
Carve a fast path for such sockets, put down all refs in one go before
calling sock_def_write_space() but guard the socket from being freed
by an RCU read section.
note: because TCP sockets are marked with SOCK_USE_WRITE_QUEUE it
doesn't add extra checks in its path.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/sock.c')
| -rw-r--r-- | net/core/sock.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/net/core/sock.c b/net/core/sock.c index 6ad22fc2eb81..ab865b04130b 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -146,6 +146,8 @@ static DEFINE_MUTEX(proto_list_mutex); static LIST_HEAD(proto_list); +static void sock_def_write_space(struct sock *sk); + /** * sk_ns_capable - General socket capability test * @sk: Socket to use a capability on or through @@ -2324,8 +2326,20 @@ void sock_wfree(struct sk_buff *skb) { struct sock *sk = skb->sk; unsigned int len = skb->truesize; + bool free; if (!sock_flag(sk, SOCK_USE_WRITE_QUEUE)) { + if (sock_flag(sk, SOCK_RCU_FREE) && + sk->sk_write_space == sock_def_write_space) { + rcu_read_lock(); + free = refcount_sub_and_test(len, &sk->sk_wmem_alloc); + sock_def_write_space(sk); + rcu_read_unlock(); + if (unlikely(free)) + __sk_free(sk); + return; + } + /* * Keep a reference on sk_wmem_alloc, this will be released * after sk_write_space() call |