From 545cd5e5ec5477c325e4098b6fd21213dceda408 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Fri, 24 Mar 2017 10:07:53 -0700 Subject: [PATCH] net: Busy polling should ignore sender CPUs This patch is a cleanup/fix for NAPI IDs following the changes that made it so that sender_cpu and napi_id were doing a better job of sharing the same location in the sk_buff. One issue I found is that we weren't validating the napi_id as being valid before we started trying to setup the busy polling. This change corrects that by using the MIN_NAPI_ID value that is now used in both allocating the NAPI IDs, as well as validating them. Signed-off-by: Alexander Duyck Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/busy_poll.h | 9 +++++++-- net/core/dev.c | 13 +++++++++---- 2 files changed, 16 insertions(+), 6 deletions(-) diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h index c0452de83086..3fcda9e70c3f 100644 --- a/include/net/busy_poll.h +++ b/include/net/busy_poll.h @@ -35,6 +35,12 @@ struct napi_struct; extern unsigned int sysctl_net_busy_read __read_mostly; extern unsigned int sysctl_net_busy_poll __read_mostly; +/* 0 - Reserved to indicate value not set + * 1..NR_CPUS - Reserved for sender_cpu + * NR_CPUS+1..~0 - Region available for NAPI IDs + */ +#define MIN_NAPI_ID ((unsigned int)(NR_CPUS + 1)) + static inline bool net_busy_loop_on(void) { return sysctl_net_busy_poll; @@ -58,10 +64,9 @@ static inline unsigned long busy_loop_end_time(void) static inline bool sk_can_busy_loop(const struct sock *sk) { - return sk->sk_ll_usec && sk->sk_napi_id && !signal_pending(current); + return sk->sk_ll_usec && !signal_pending(current); } - static inline bool busy_loop_timeout(unsigned long end_time) { unsigned long now = busy_loop_us_clock(); diff --git a/net/core/dev.c b/net/core/dev.c index 7869ae3837ca..ab337bf5bbf4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5066,15 +5066,20 @@ bool sk_busy_loop(struct sock *sk, int nonblock) int (*napi_poll)(struct napi_struct *napi, int budget); void *have_poll_lock = NULL; struct napi_struct *napi; + unsigned int napi_id; int rc; restart: + napi_id = READ_ONCE(sk->sk_napi_id); + if (napi_id < MIN_NAPI_ID) + return 0; + rc = false; napi_poll = NULL; rcu_read_lock(); - napi = napi_by_id(sk->sk_napi_id); + napi = napi_by_id(napi_id); if (!napi) goto out; @@ -5143,10 +5148,10 @@ static void napi_hash_add(struct napi_struct *napi) spin_lock(&napi_hash_lock); - /* 0..NR_CPUS+1 range is reserved for sender_cpu use */ + /* 0..NR_CPUS range is reserved for sender_cpu use */ do { - if (unlikely(++napi_gen_id < NR_CPUS + 1)) - napi_gen_id = NR_CPUS + 1; + if (unlikely(++napi_gen_id < MIN_NAPI_ID)) + napi_gen_id = MIN_NAPI_ID; } while (napi_by_id(napi_gen_id)); napi->napi_id = napi_gen_id; -- 2.30.2