From 90a9631cf8c27a2b4702af600cad390fcabb88fb Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Fri, 1 Sep 2017 11:29:26 -0700 Subject: [PATCH] bpf: sockmap update/simplify memory accounting scheme Instead of tracking wmem_queued and sk_mem_charge by incrementing in the verdict SK_REDIRECT paths and decrementing in the tx work path use skb_set_owner_w and sock_writeable helpers. This solves a few issues with the current code. First, in SK_REDIRECT inc on sk_wmem_queued and sk_mem_charge were being done without the peers sock lock being held. Under stress this can result in accounting errors when tx work and/or multiple verdict decisions are working on the peer psock. Additionally, this cleans up the code because we can rely on the default destructor to decrement memory accounting on kfree_skb. Also this will trigger sk_write_space when space becomes available on kfree_skb() which wasn't happening before and prevent __sk_free from being called until all in-flight packets are completed. Fixes: 174a79ff9515 ("bpf: sockmap with sk redirect support") Signed-off-by: John Fastabend Acked-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- kernel/bpf/sockmap.c | 18 +++++++----------- 1 file changed, 7 insertions(+), 11 deletions(-) diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c index db0d99d2fe18..f6ffde9c6a68 100644 --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -111,7 +111,7 @@ static int smap_verdict_func(struct smap_psock *psock, struct sk_buff *skb) static void smap_do_verdict(struct smap_psock *psock, struct sk_buff *skb) { - struct sock *sock; + struct sock *sk; int rc; /* Because we use per cpu values to feed input from sock redirect @@ -123,16 +123,16 @@ static void smap_do_verdict(struct smap_psock *psock, struct sk_buff *skb) rc = smap_verdict_func(psock, skb); switch (rc) { case SK_REDIRECT: - sock = do_sk_redirect_map(); + sk = do_sk_redirect_map(); preempt_enable(); - if (likely(sock)) { - struct smap_psock *peer = smap_psock_sk(sock); + if (likely(sk)) { + struct smap_psock *peer = smap_psock_sk(sk); if (likely(peer && test_bit(SMAP_TX_RUNNING, &peer->state) && - sk_stream_memory_free(peer->sock))) { - peer->sock->sk_wmem_queued += skb->truesize; - sk_mem_charge(peer->sock, skb->truesize); + !sock_flag(sk, SOCK_DEAD) && + sock_writeable(sk))) { + skb_set_owner_w(skb, sk); skb_queue_tail(&peer->rxqueue, skb); schedule_work(&peer->tx_work); break; @@ -282,16 +282,12 @@ start: /* Hard errors break pipe and stop xmit */ smap_report_sk_error(psock, n ? -n : EPIPE); clear_bit(SMAP_TX_RUNNING, &psock->state); - sk_mem_uncharge(psock->sock, skb->truesize); - psock->sock->sk_wmem_queued -= skb->truesize; kfree_skb(skb); goto out; } rem -= n; off += n; } while (rem); - sk_mem_uncharge(psock->sock, skb->truesize); - psock->sock->sk_wmem_queued -= skb->truesize; kfree_skb(skb); } out: -- 2.20.1