[PATCH v4 bpf-next 02/11] tcp: Add num_closed_socks to struct sock_reuseport.
From: Kuniyuki Iwashima
Date: Mon Apr 26 2021 - 23:47:38 EST
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@xxxxxxxxxxxx>
---
include/net/sock_reuseport.h | 5 ++-
net/core/sock_reuseport.c | 76 +++++++++++++++++++++++++++---------
2 files changed, 60 insertions(+), 21 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..079bd1aca0e7 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,
+ 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 +115,8 @@ int reuseport_alloc(struct sock *sk, bool bind_inany)
}
reuse->reuseport_id = id;
- reuse->socks[0] = sk;
- reuse->num_socks = 1;
reuse->bind_inany = bind_inany;
+ __reuseport_add_sock(sk, reuse);
rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
out:
@@ -98,6 +140,7 @@ 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 +148,13 @@ 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->num_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 +205,7 @@ 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 +213,7 @@ 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 +227,6 @@ 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 +243,11 @@ 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 +312,7 @@ 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)
--
2.30.2