diff options
| author | Eric Dumazet <edumazet@google.com> | 2024-12-15 17:56:29 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-12-17 19:37:48 -0800 |
| commit | a853c609504e2d1d83e71285e3622fda1f1451d8 (patch) | |
| tree | b6d9cd4e2333cf6afc87beb0bc7675bc73777006 /net/ipv4/inetpeer.c | |
| parent | 50b362f21d6c10b0f7939c1482c6a1b43da82f1a (diff) | |
inetpeer: do not get a refcount in inet_getpeer()
All inet_getpeer() callers except ip4_frag_init() don't need
to acquire a permanent refcount on the inetpeer.
They can switch to full RCU protection.
Move the refcount_inc_not_zero() into ip4_frag_init(),
so that all the other callers no longer have to
perform a pair of expensive atomic operations on
a possibly contended cache line.
inet_putpeer() no longer needs to be exported.
After this patch, my DUT can receive 8,400,000 UDP packets
per second targeting closed ports, using 50% less cpu cycles
than before.
Also change two calls to l3mdev_master_ifindex() by
l3mdev_master_ifindex_rcu() (Ido ideas)
Fixes: 8c2bd38b95f7 ("icmp: change the order of rate limits")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241215175629.1248773-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/inetpeer.c')
| -rw-r--r-- | net/ipv4/inetpeer.c | 8 |
1 files changed, 2 insertions, 6 deletions
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c index 28c3ae5bc4a0..e02484f4d22b 100644 --- a/net/ipv4/inetpeer.c +++ b/net/ipv4/inetpeer.c @@ -109,8 +109,6 @@ static struct inet_peer *lookup(const struct inetpeer_addr *daddr, p = rb_entry(parent, struct inet_peer, rb_node); cmp = inetpeer_addr_cmp(daddr, &p->daddr); if (cmp == 0) { - if (!refcount_inc_not_zero(&p->refcnt)) - break; now = jiffies; if (READ_ONCE(p->dtime) != now) WRITE_ONCE(p->dtime, now); @@ -169,6 +167,7 @@ static void inet_peer_gc(struct inet_peer_base *base, } } +/* Must be called under RCU : No refcount change is done here. */ struct inet_peer *inet_getpeer(struct inet_peer_base *base, const struct inetpeer_addr *daddr) { @@ -179,10 +178,8 @@ struct inet_peer *inet_getpeer(struct inet_peer_base *base, /* Attempt a lockless lookup first. * Because of a concurrent writer, we might not find an existing entry. */ - rcu_read_lock(); seq = read_seqbegin(&base->lock); p = lookup(daddr, base, seq, NULL, &gc_cnt, &parent, &pp); - rcu_read_unlock(); if (p) return p; @@ -200,7 +197,7 @@ struct inet_peer *inet_getpeer(struct inet_peer_base *base, if (p) { p->daddr = *daddr; p->dtime = (__u32)jiffies; - refcount_set(&p->refcnt, 2); + refcount_set(&p->refcnt, 1); atomic_set(&p->rid, 0); p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW; p->rate_tokens = 0; @@ -228,7 +225,6 @@ void inet_putpeer(struct inet_peer *p) if (refcount_dec_and_test(&p->refcnt)) kfree_rcu(p, rcu); } -EXPORT_SYMBOL_GPL(inet_putpeer); /* * Check transmit rate limitation for given message. |