From: Kuniyuki Iwashima kuniyu@amazon.co.jp
[ Upstream commit 5c040eaf5d1753aafe12989ca712175df0b9c436 ]
As noted in the following commit, a closed listener has to hold the reference to the reuseport group for socket migration. This patch adds a field (num_closed_socks) to struct sock_reuseport to manage closed sockets within the same reuseport group. Moreover, this and the following commits introduce some helper functions to split socks[] into two sections and keep TCP_LISTEN and TCP_CLOSE sockets in each section. Like a double-ended queue, we will place TCP_LISTEN sockets from the front and TCP_CLOSE sockets from the end.
TCP_LISTEN----------> <-------TCP_CLOSE +---+---+ --- +---+ --- +---+ --- +---+ | 0 | 1 | ... | i | ... | j | ... | k | +---+---+ --- +---+ --- +---+ --- +---+
i = num_socks - 1 j = max_socks - num_closed_socks k = max_socks - 1
This patch also extends reuseport_add_sock() and reuseport_grow() to support num_closed_socks.
Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.co.jp Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Eric Dumazet edumazet@google.com Acked-by: Martin KaFai Lau kafai@fb.com Link: https://lore.kernel.org/bpf/20210612123224.12525-3-kuniyu@amazon.co.jp Stable-dep-of: 69421bf98482 ("udp: Update reuse->has_conns under reuseport_lock.") Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/sock_reuseport.h | 5 ++- net/core/sock_reuseport.c | 75 +++++++++++++++++++++++++++--------- 2 files changed, 60 insertions(+), 20 deletions(-)
diff --git a/include/net/sock_reuseport.h b/include/net/sock_reuseport.h index 505f1e18e9bf..0e558ca7afbf 100644 --- a/include/net/sock_reuseport.h +++ b/include/net/sock_reuseport.h @@ -13,8 +13,9 @@ extern spinlock_t reuseport_lock; struct sock_reuseport { struct rcu_head rcu;
- u16 max_socks; /* length of socks */ - u16 num_socks; /* elements in socks */ + u16 max_socks; /* length of socks */ + u16 num_socks; /* elements in socks */ + u16 num_closed_socks; /* closed elements in socks */ /* The last synq overflow event timestamp of this * reuse->socks[] group. */ diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c index b065f0a103ed..f478c65a281b 100644 --- a/net/core/sock_reuseport.c +++ b/net/core/sock_reuseport.c @@ -18,6 +18,49 @@ DEFINE_SPINLOCK(reuseport_lock);
static DEFINE_IDA(reuseport_ida);
+static int reuseport_sock_index(struct sock *sk, + const struct sock_reuseport *reuse, + bool closed) +{ + int left, right; + + if (!closed) { + left = 0; + right = reuse->num_socks; + } else { + left = reuse->max_socks - reuse->num_closed_socks; + right = reuse->max_socks; + } + + for (; left < right; left++) + if (reuse->socks[left] == sk) + return left; + return -1; +} + +static void __reuseport_add_sock(struct sock *sk, + struct sock_reuseport *reuse) +{ + reuse->socks[reuse->num_socks] = sk; + /* paired with smp_rmb() in reuseport_select_sock() */ + smp_wmb(); + reuse->num_socks++; +} + +static bool __reuseport_detach_sock(struct sock *sk, + struct sock_reuseport *reuse) +{ + int i = reuseport_sock_index(sk, reuse, false); + + if (i == -1) + return false; + + reuse->socks[i] = reuse->socks[reuse->num_socks - 1]; + reuse->num_socks--; + + return true; +} + static struct sock_reuseport *__reuseport_alloc(unsigned int max_socks) { unsigned int size = sizeof(struct sock_reuseport) + @@ -72,9 +115,9 @@ int reuseport_alloc(struct sock *sk, bool bind_inany) }
reuse->reuseport_id = id; + reuse->bind_inany = bind_inany; reuse->socks[0] = sk; reuse->num_socks = 1; - reuse->bind_inany = bind_inany; rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
out: @@ -98,6 +141,7 @@ static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse) return NULL;
more_reuse->num_socks = reuse->num_socks; + more_reuse->num_closed_socks = reuse->num_closed_socks; more_reuse->prog = reuse->prog; more_reuse->reuseport_id = reuse->reuseport_id; more_reuse->bind_inany = reuse->bind_inany; @@ -105,9 +149,13 @@ static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse)
memcpy(more_reuse->socks, reuse->socks, reuse->num_socks * sizeof(struct sock *)); + memcpy(more_reuse->socks + + (more_reuse->max_socks - more_reuse->num_closed_socks), + reuse->socks + (reuse->max_socks - reuse->num_closed_socks), + reuse->num_closed_socks * sizeof(struct sock *)); more_reuse->synq_overflow_ts = READ_ONCE(reuse->synq_overflow_ts);
- for (i = 0; i < reuse->num_socks; ++i) + for (i = 0; i < reuse->max_socks; ++i) rcu_assign_pointer(reuse->socks[i]->sk_reuseport_cb, more_reuse);
@@ -158,7 +206,7 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany) return -EBUSY; }
- if (reuse->num_socks == reuse->max_socks) { + if (reuse->num_socks + reuse->num_closed_socks == reuse->max_socks) { reuse = reuseport_grow(reuse); if (!reuse) { spin_unlock_bh(&reuseport_lock); @@ -166,10 +214,7 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany) } }
- reuse->socks[reuse->num_socks] = sk; - /* paired with smp_rmb() in reuseport_select_sock() */ - smp_wmb(); - reuse->num_socks++; + __reuseport_add_sock(sk, reuse); rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
spin_unlock_bh(&reuseport_lock); @@ -183,7 +228,6 @@ EXPORT_SYMBOL(reuseport_add_sock); void reuseport_detach_sock(struct sock *sk) { struct sock_reuseport *reuse; - int i;
spin_lock_bh(&reuseport_lock); reuse = rcu_dereference_protected(sk->sk_reuseport_cb, @@ -200,16 +244,11 @@ void reuseport_detach_sock(struct sock *sk) bpf_sk_reuseport_detach(sk);
rcu_assign_pointer(sk->sk_reuseport_cb, NULL); + __reuseport_detach_sock(sk, reuse); + + if (reuse->num_socks + reuse->num_closed_socks == 0) + call_rcu(&reuse->rcu, reuseport_free_rcu);
- for (i = 0; i < reuse->num_socks; i++) { - if (reuse->socks[i] == sk) { - reuse->socks[i] = reuse->socks[reuse->num_socks - 1]; - reuse->num_socks--; - if (reuse->num_socks == 0) - call_rcu(&reuse->rcu, reuseport_free_rcu); - break; - } - } spin_unlock_bh(&reuseport_lock); } EXPORT_SYMBOL(reuseport_detach_sock); @@ -274,7 +313,7 @@ struct sock *reuseport_select_sock(struct sock *sk, prog = rcu_dereference(reuse->prog); socks = READ_ONCE(reuse->num_socks); if (likely(socks)) { - /* paired with smp_wmb() in reuseport_add_sock() */ + /* paired with smp_wmb() in __reuseport_add_sock() */ smp_rmb();
if (!prog || !skb)