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net: Busy polling should ignore sender CPUs

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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 <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck
2017-03-24 10:07:53 -07:00
committed by David S. Miller
parent dcb421f427
commit 545cd5e5ec
2 changed files with 16 additions and 6 deletions
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13
net/core/dev.c
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@@ -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;