diff options
| -rw-r--r-- | include/linux/netdevice.h | 10 | ||||
| -rw-r--r-- | net/core/dev.c | 102 |
2 files changed, 92 insertions, 20 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 86bacf6a64f0..e71de66e3792 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -334,6 +334,16 @@ enum { NAPI_STATE_NPSVC, /* Netpoll - don't dequeue from poll_list */ NAPI_STATE_HASHED, /* In NAPI hash (busy polling possible) */ NAPI_STATE_NO_BUSY_POLL,/* Do not add in napi_hash, no busy polling */ + NAPI_STATE_IN_BUSY_POLL,/* sk_busy_loop() owns this NAPI */ +}; + +enum { + NAPIF_STATE_SCHED = (1UL << NAPI_STATE_SCHED), + NAPIF_STATE_DISABLE = (1UL << NAPI_STATE_DISABLE), + NAPIF_STATE_NPSVC = (1UL << NAPI_STATE_NPSVC), + NAPIF_STATE_HASHED = (1UL << NAPI_STATE_HASHED), + NAPIF_STATE_NO_BUSY_POLL = (1UL << NAPI_STATE_NO_BUSY_POLL), + NAPIF_STATE_IN_BUSY_POLL = (1UL << NAPI_STATE_IN_BUSY_POLL), }; enum gro_result { diff --git a/net/core/dev.c b/net/core/dev.c index 6deba68ad9e4..369dcc8efc01 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4902,6 +4902,12 @@ void __napi_complete(struct napi_struct *n) { BUG_ON(!test_bit(NAPI_STATE_SCHED, &n->state)); + /* Some drivers call us directly, instead of calling + * napi_complete_done(). + */ + if (unlikely(test_bit(NAPI_STATE_IN_BUSY_POLL, &n->state))) + return; + list_del_init(&n->poll_list); smp_mb__before_atomic(); clear_bit(NAPI_STATE_SCHED, &n->state); @@ -4913,10 +4919,13 @@ void napi_complete_done(struct napi_struct *n, int work_done) unsigned long flags; /* - * don't let napi dequeue from the cpu poll list - * just in case its running on a different cpu + * 1) Don't let napi dequeue from the cpu poll list + * just in case its running on a different cpu. + * 2) If we are busy polling, do nothing here, we have + * the guarantee we will be called later. */ - if (unlikely(test_bit(NAPI_STATE_NPSVC, &n->state))) + if (unlikely(n->state & (NAPIF_STATE_NPSVC | + NAPIF_STATE_IN_BUSY_POLL))) return; if (n->gro_list) { @@ -4956,13 +4965,41 @@ static struct napi_struct *napi_by_id(unsigned int napi_id) } #if defined(CONFIG_NET_RX_BUSY_POLL) + #define BUSY_POLL_BUDGET 8 + +static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock) +{ + int rc; + + clear_bit(NAPI_STATE_IN_BUSY_POLL, &napi->state); + + local_bh_disable(); + + /* All we really want here is to re-enable device interrupts. + * Ideally, a new ndo_busy_poll_stop() could avoid another round. + */ + rc = napi->poll(napi, BUSY_POLL_BUDGET); + netpoll_poll_unlock(have_poll_lock); + if (rc == BUSY_POLL_BUDGET) + __napi_schedule(napi); + local_bh_enable(); + if (local_softirq_pending()) + do_softirq(); +} + bool sk_busy_loop(struct sock *sk, int nonblock) { unsigned long end_time = !nonblock ? sk_busy_loop_end_time(sk) : 0; + int (*napi_poll)(struct napi_struct *napi, int budget); int (*busy_poll)(struct napi_struct *dev); + void *have_poll_lock = NULL; struct napi_struct *napi; - int rc = false; + int rc; + +restart: + rc = false; + napi_poll = NULL; rcu_read_lock(); @@ -4973,24 +5010,33 @@ bool sk_busy_loop(struct sock *sk, int nonblock) /* Note: ndo_busy_poll method is optional in linux-4.5 */ busy_poll = napi->dev->netdev_ops->ndo_busy_poll; - do { + preempt_disable(); + for (;;) { rc = 0; local_bh_disable(); if (busy_poll) { rc = busy_poll(napi); - } else if (napi_schedule_prep(napi)) { - void *have = netpoll_poll_lock(napi); - - if (test_bit(NAPI_STATE_SCHED, &napi->state)) { - rc = napi->poll(napi, BUSY_POLL_BUDGET); - trace_napi_poll(napi, rc, BUSY_POLL_BUDGET); - if (rc == BUSY_POLL_BUDGET) { - napi_complete_done(napi, rc); - napi_schedule(napi); - } - } - netpoll_poll_unlock(have); + goto count; } + if (!napi_poll) { + unsigned long val = READ_ONCE(napi->state); + + /* If multiple threads are competing for this napi, + * we avoid dirtying napi->state as much as we can. + */ + if (val & (NAPIF_STATE_DISABLE | NAPIF_STATE_SCHED | + NAPIF_STATE_IN_BUSY_POLL)) + goto count; + if (cmpxchg(&napi->state, val, + val | NAPIF_STATE_IN_BUSY_POLL | + NAPIF_STATE_SCHED) != val) + goto count; + have_poll_lock = netpoll_poll_lock(napi); + napi_poll = napi->poll; + } + rc = napi_poll(napi, BUSY_POLL_BUDGET); + trace_napi_poll(napi, rc, BUSY_POLL_BUDGET); +count: if (rc > 0) __NET_ADD_STATS(sock_net(sk), LINUX_MIB_BUSYPOLLRXPACKETS, rc); @@ -4999,10 +5045,26 @@ bool sk_busy_loop(struct sock *sk, int nonblock) if (rc == LL_FLUSH_FAILED) break; /* permanent failure */ - cpu_relax(); - } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) && - !need_resched() && !busy_loop_timeout(end_time)); + if (nonblock || !skb_queue_empty(&sk->sk_receive_queue) || + busy_loop_timeout(end_time)) + break; + if (unlikely(need_resched())) { + if (napi_poll) + busy_poll_stop(napi, have_poll_lock); + preempt_enable(); + rcu_read_unlock(); + cond_resched(); + rc = !skb_queue_empty(&sk->sk_receive_queue); + if (rc || busy_loop_timeout(end_time)) + return rc; + goto restart; + } + cpu_relax_lowlatency(); + } + if (napi_poll) + busy_poll_stop(napi, have_poll_lock); + preempt_enable(); rc = !skb_queue_empty(&sk->sk_receive_queue); out: rcu_read_unlock(); |