* [RFC] af-packet: Save reference to bound network device.
@ 2011-05-25 21:56 greearb
2011-05-25 22:01 ` David Miller
0 siblings, 1 reply; 7+ messages in thread
From: greearb @ 2011-05-25 21:56 UTC (permalink / raw)
To: netdev; +Cc: Ben Greear
From: Ben Greear <greearb@candelatech.com>
This saves a network device lookup on each packet transmitted,
for sockets that are bound to a network device.
Signed-off-by: Ben Greear <greearb@candelatech.com>
---
:100644 100644 4005b24... ba16759... M net/packet/af_packet.c
net/packet/af_packet.c | 48 +++++++++++++++++++++++++++++++++++-------------
1 files changed, 35 insertions(+), 13 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 4005b24..ba16759 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -201,8 +201,9 @@ struct packet_sock {
auxdata:1,
origdev:1,
has_vnet_hdr:1;
- int ifindex; /* bound device */
+ int ifindex; /* bound device id */
__be16 num;
+ struct net_device *bound_dev; /* bound device */
struct packet_mclist *mclist;
atomic_t mapped;
enum tpacket_versions tp_version;
@@ -987,8 +988,9 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
{
struct sk_buff *skb;
- struct net_device *dev;
+ struct net_device *dev = NULL;
__be16 proto;
+ bool need_rls_dev = false;
int ifindex, err, reserve = 0;
void *ph;
struct sockaddr_ll *saddr = (struct sockaddr_ll *)msg->msg_name;
@@ -1002,6 +1004,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
err = -EBUSY;
if (saddr == NULL) {
ifindex = po->ifindex;
+ dev = po->bound_dev;
proto = po->num;
addr = NULL;
} else {
@@ -1017,7 +1020,10 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
addr = saddr->sll_addr;
}
- dev = dev_get_by_index(sock_net(&po->sk), ifindex);
+ if (!dev) {
+ dev = dev_get_by_index(sock_net(&po->sk), ifindex);
+ need_rls_dev = true;
+ }
err = -ENXIO;
if (unlikely(dev == NULL))
goto out;
@@ -1103,7 +1109,8 @@ out_status:
__packet_set_status(po, ph, status);
kfree_skb(skb);
out_put:
- dev_put(dev);
+ if (need_rls_dev)
+ dev_put(dev);
out:
mutex_unlock(&po->pg_vec_lock);
return err;
@@ -1139,8 +1146,9 @@ static int packet_snd(struct socket *sock,
struct sock *sk = sock->sk;
struct sockaddr_ll *saddr = (struct sockaddr_ll *)msg->msg_name;
struct sk_buff *skb;
- struct net_device *dev;
+ struct net_device *dev = NULL;
__be16 proto;
+ bool need_rls_dev = false;
unsigned char *addr;
int ifindex, err, reserve = 0;
struct virtio_net_hdr vnet_hdr = { 0 };
@@ -1161,6 +1169,7 @@ static int packet_snd(struct socket *sock,
if (saddr == NULL) {
ifindex = po->ifindex;
+ dev = po->bound_dev;
proto = po->num;
addr = NULL;
} else {
@@ -1174,8 +1183,11 @@ static int packet_snd(struct socket *sock,
addr = saddr->sll_addr;
}
+ if (!dev) {
+ dev = dev_get_by_index(sock_net(sk), ifindex);
+ need_rls_dev = true;
+ }
- dev = dev_get_by_index(sock_net(sk), ifindex);
err = -ENXIO;
if (dev == NULL)
goto out_unlock;
@@ -1315,14 +1327,15 @@ static int packet_snd(struct socket *sock,
if (err > 0 && (err = net_xmit_errno(err)) != 0)
goto out_unlock;
- dev_put(dev);
+ if (need_rls_dev)
+ dev_put(dev);
return len;
out_free:
kfree_skb(skb);
out_unlock:
- if (dev)
+ if (dev && need_rls_dev)
dev_put(dev);
out:
return err;
@@ -1372,6 +1385,12 @@ static int packet_release(struct socket *sock)
__dev_remove_pack(&po->prot_hook);
__sock_put(sk);
}
+
+ if (po->bound_dev) {
+ dev_put(po->bound_dev);
+ po->bound_dev = NULL;
+ }
+
spin_unlock(&po->bind_lock);
packet_flush_mclist(sk);
@@ -1428,6 +1447,9 @@ static int packet_do_bind(struct sock *sk, struct net_device *dev, __be16 protoc
po->prot_hook.dev = dev;
po->ifindex = dev ? dev->ifindex : 0;
+ if (po->bound_dev)
+ dev_put(po->bound_dev);
+ po->bound_dev = dev;
if (protocol == 0)
goto out_unlock;
@@ -1469,10 +1491,8 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
strlcpy(name, uaddr->sa_data, sizeof(name));
dev = dev_get_by_name(sock_net(sk), name);
- if (dev) {
+ if (dev)
err = packet_do_bind(sk, dev, pkt_sk(sk)->num);
- dev_put(dev);
- }
return err;
}
@@ -1500,8 +1520,6 @@ static int packet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len
goto out;
}
err = packet_do_bind(sk, dev, sll->sll_protocol ? : pkt_sk(sk)->num);
- if (dev)
- dev_put(dev);
out:
return err;
@@ -2266,6 +2284,10 @@ static int packet_notifier(struct notifier_block *this, unsigned long msg, void
}
if (msg == NETDEV_UNREGISTER) {
po->ifindex = -1;
+ if (po->bound_dev) {
+ dev_put(po->bound_dev);
+ po->bound_dev = NULL;
+ }
po->prot_hook.dev = NULL;
}
spin_unlock(&po->bind_lock);
--
1.7.3.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [RFC] af-packet: Save reference to bound network device.
2011-05-25 21:56 [RFC] af-packet: Save reference to bound network device greearb
@ 2011-05-25 22:01 ` David Miller
2011-05-25 22:05 ` Ben Greear
0 siblings, 1 reply; 7+ messages in thread
From: David Miller @ 2011-05-25 22:01 UTC (permalink / raw)
To: greearb; +Cc: netdev
From: greearb@candelatech.com
Date: Wed, 25 May 2011 14:56:42 -0700
> From: Ben Greear <greearb@candelatech.com>
>
> This saves a network device lookup on each packet transmitted,
> for sockets that are bound to a network device.
>
> Signed-off-by: Ben Greear <greearb@candelatech.com>
You can't hold onto devices like this unless you also add a netdev
event notifier that will release it. Otherwise we'll hang on net
driver module unload until the packet socket is closed.
I don't think you really want to walk all pf-packet sockets on netdev
events just to do this.
dev_get_by_index(,_rcu}() is insanely cheap, I doubt it's showing up
on your profiles at all.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [RFC] af-packet: Save reference to bound network device.
2011-05-25 22:01 ` David Miller
@ 2011-05-25 22:05 ` Ben Greear
2011-05-25 22:14 ` David Miller
0 siblings, 1 reply; 7+ messages in thread
From: Ben Greear @ 2011-05-25 22:05 UTC (permalink / raw)
To: David Miller; +Cc: netdev
On 05/25/2011 03:01 PM, David Miller wrote:
> From: greearb@candelatech.com
> Date: Wed, 25 May 2011 14:56:42 -0700
>
>> From: Ben Greear<greearb@candelatech.com>
>>
>> This saves a network device lookup on each packet transmitted,
>> for sockets that are bound to a network device.
>>
>> Signed-off-by: Ben Greear<greearb@candelatech.com>
>
> You can't hold onto devices like this unless you also add a netdev
> event notifier that will release it. Otherwise we'll hang on net
> driver module unload until the packet socket is closed.
>
> I don't think you really want to walk all pf-packet sockets on netdev
> events just to do this.
Doesn't this piece of code take care of that?
I tested with rmmod..but of course I could have missed something.
@@ -2266,6 +2284,10 @@ static int packet_notifier(struct notifier_block *this, unsigned long msg, void
}
if (msg == NETDEV_UNREGISTER) {
po->ifindex = -1;
+ if (po->bound_dev) {
+ dev_put(po->bound_dev);
+ po->bound_dev = NULL;
+ }
po->prot_hook.dev = NULL;
}
spin_unlock(&po->bind_lock);
>
> dev_get_by_index(,_rcu}() is insanely cheap, I doubt it's showing up
> on your profiles at all.
I admit it was a small change...maybe 5Mbps (from 165 to 170Mbps in
this particular test), but it did seem to improve things a bit.
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [RFC] af-packet: Save reference to bound network device.
2011-05-25 22:05 ` Ben Greear
@ 2011-05-25 22:14 ` David Miller
2011-05-25 22:22 ` Ben Greear
2011-05-25 22:36 ` Ben Greear
0 siblings, 2 replies; 7+ messages in thread
From: David Miller @ 2011-05-25 22:14 UTC (permalink / raw)
To: greearb; +Cc: netdev
From: Ben Greear <greearb@candelatech.com>
Date: Wed, 25 May 2011 15:05:10 -0700
> Doesn't this piece of code take care of that?
> I tested with rmmod..but of course I could have missed something.
>
> @@ -2266,6 +2284,10 @@ static int packet_notifier(struct
> notifier_block *this, unsigned long msg, void
> }
> if (msg == NETDEV_UNREGISTER) {
> po->ifindex = -1;
> + if (po->bound_dev) {
> + dev_put(po->bound_dev);
> + po->bound_dev = NULL;
> + }
> po->prot_hook.dev = NULL;
> }
> spin_unlock(&po->bind_lock);
>
Indeed, it should, thanks for pointing that out.
Wait a second, why do you need to store the device a second
time, can't you get at po->prot_hook.dev in all the necessary
spots?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [RFC] af-packet: Save reference to bound network device.
2011-05-25 22:14 ` David Miller
@ 2011-05-25 22:22 ` Ben Greear
2011-05-25 22:36 ` Ben Greear
1 sibling, 0 replies; 7+ messages in thread
From: Ben Greear @ 2011-05-25 22:22 UTC (permalink / raw)
To: David Miller; +Cc: netdev
On 05/25/2011 03:14 PM, David Miller wrote:
> From: Ben Greear<greearb@candelatech.com>
> Date: Wed, 25 May 2011 15:05:10 -0700
>
>> Doesn't this piece of code take care of that?
>> I tested with rmmod..but of course I could have missed something.
>>
>> @@ -2266,6 +2284,10 @@ static int packet_notifier(struct
>> notifier_block *this, unsigned long msg, void
>> }
>> if (msg == NETDEV_UNREGISTER) {
>> po->ifindex = -1;
>> + if (po->bound_dev) {
>> + dev_put(po->bound_dev);
>> + po->bound_dev = NULL;
>> + }
>> po->prot_hook.dev = NULL;
>> }
>> spin_unlock(&po->bind_lock);
>>
>
> Indeed, it should, thanks for pointing that out.
>
> Wait a second, why do you need to store the device a second
> time, can't you get at po->prot_hook.dev in all the necessary
> spots?
I think so...I'll poke at the code a bit and run some more
tests using that instead...
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [RFC] af-packet: Save reference to bound network device.
2011-05-25 22:14 ` David Miller
2011-05-25 22:22 ` Ben Greear
@ 2011-05-25 22:36 ` Ben Greear
2011-05-25 22:42 ` David Miller
1 sibling, 1 reply; 7+ messages in thread
From: Ben Greear @ 2011-05-25 22:36 UTC (permalink / raw)
To: David Miller; +Cc: netdev
On 05/25/2011 03:14 PM, David Miller wrote:
> From: Ben Greear<greearb@candelatech.com>
> Date: Wed, 25 May 2011 15:05:10 -0700
>
>> Doesn't this piece of code take care of that?
>> I tested with rmmod..but of course I could have missed something.
>>
>> @@ -2266,6 +2284,10 @@ static int packet_notifier(struct
>> notifier_block *this, unsigned long msg, void
>> }
>> if (msg == NETDEV_UNREGISTER) {
>> po->ifindex = -1;
>> + if (po->bound_dev) {
>> + dev_put(po->bound_dev);
>> + po->bound_dev = NULL;
>> + }
>> po->prot_hook.dev = NULL;
>> }
>> spin_unlock(&po->bind_lock);
>>
>
> Indeed, it should, thanks for pointing that out.
>
> Wait a second, why do you need to store the device a second
> time, can't you get at po->prot_hook.dev in all the necessary
> spots?
I can't see where the code holds any reference to prot_hook.dev.
(It just assigns the pointer and then does a dev_put()).
Maybe it gets away with it because a NETDEV_UNREGISTER event
is always sent?
Or, maybe we should hold a ref to it?
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [RFC] af-packet: Save reference to bound network device.
2011-05-25 22:36 ` Ben Greear
@ 2011-05-25 22:42 ` David Miller
0 siblings, 0 replies; 7+ messages in thread
From: David Miller @ 2011-05-25 22:42 UTC (permalink / raw)
To: greearb; +Cc: netdev
From: Ben Greear <greearb@candelatech.com>
Date: Wed, 25 May 2011 15:36:55 -0700
> I can't see where the code holds any reference to prot_hook.dev.
> (It just assigns the pointer and then does a dev_put()).
>
> Maybe it gets away with it because a NETDEV_UNREGISTER event
> is always sent?
I think that is precisely the property it is depending upon.
It may seem sketchy, but as far as I can tell it's completely
legal.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2011-05-25 22:42 UTC | newest]
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2011-05-25 21:56 [RFC] af-packet: Save reference to bound network device greearb
2011-05-25 22:01 ` David Miller
2011-05-25 22:05 ` Ben Greear
2011-05-25 22:14 ` David Miller
2011-05-25 22:22 ` Ben Greear
2011-05-25 22:36 ` Ben Greear
2011-05-25 22:42 ` David Miller
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