* [PATCH] l2tp: cast l2tp traffic counter to unsigned
@ 2017-06-09 14:29 Dominik Heidler
2017-06-09 22:16 ` Stephen Hemminger
0 siblings, 1 reply; 6+ messages in thread
From: Dominik Heidler @ 2017-06-09 14:29 UTC (permalink / raw)
To: netdev, linux-kernel; +Cc: Dominik Heidler, Tom Parkin
This fixes a counter problem on 32bit systems:
When the rx_bytes counter reached 2 GiB, it jumpd to (2^64 Bytes - 2GiB) Bytes.
rtnl_link_stats64 has __u64 type and atomic_long_read returns
atomic_long_t which is signed. Due to the conversation
we get an incorrect value on 32bit systems if the MSB of
the atomic_long_t value is set.
CC: Tom Parkin <tparkin@katalix.com>
Fixes: 7b7c0719cd7a ("l2tp: avoid deadlock in l2tp stats update")
Signed-off-by: Dominik Heidler <dheidler@suse.de>
---
net/l2tp/l2tp_eth.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index 8b21af7321b9..668a75e002e9 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -114,12 +114,13 @@ static void l2tp_eth_get_stats64(struct net_device *dev,
{
struct l2tp_eth *priv = netdev_priv(dev);
- stats->tx_bytes = atomic_long_read(&priv->tx_bytes);
- stats->tx_packets = atomic_long_read(&priv->tx_packets);
- stats->tx_dropped = atomic_long_read(&priv->tx_dropped);
- stats->rx_bytes = atomic_long_read(&priv->rx_bytes);
- stats->rx_packets = atomic_long_read(&priv->rx_packets);
- stats->rx_errors = atomic_long_read(&priv->rx_errors);
+ stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes);
+ stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
+ stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
+ stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes);
+ stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
+ stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors);
+
}
static const struct net_device_ops l2tp_eth_netdev_ops = {
--
2.13.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] l2tp: cast l2tp traffic counter to unsigned
2017-06-09 14:29 [PATCH] l2tp: cast l2tp traffic counter to unsigned Dominik Heidler
@ 2017-06-09 22:16 ` Stephen Hemminger
2017-06-10 0:29 ` Eric Dumazet
0 siblings, 1 reply; 6+ messages in thread
From: Stephen Hemminger @ 2017-06-09 22:16 UTC (permalink / raw)
To: Dominik Heidler; +Cc: netdev, linux-kernel, Tom Parkin
On Fri, 9 Jun 2017 16:29:47 +0200
Dominik Heidler <dheidler@suse.de> wrote:
> This fixes a counter problem on 32bit systems:
> When the rx_bytes counter reached 2 GiB, it jumpd to (2^64 Bytes - 2GiB) Bytes.
>
> rtnl_link_stats64 has __u64 type and atomic_long_read returns
> atomic_long_t which is signed. Due to the conversation
> we get an incorrect value on 32bit systems if the MSB of
> the atomic_long_t value is set.
>
> CC: Tom Parkin <tparkin@katalix.com>
> Fixes: 7b7c0719cd7a ("l2tp: avoid deadlock in l2tp stats update")
> Signed-off-by: Dominik Heidler <dheidler@suse.de>
> ---
> net/l2tp/l2tp_eth.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
> index 8b21af7321b9..668a75e002e9 100644
> --- a/net/l2tp/l2tp_eth.c
> +++ b/net/l2tp/l2tp_eth.c
> @@ -114,12 +114,13 @@ static void l2tp_eth_get_stats64(struct net_device *dev,
> {
> struct l2tp_eth *priv = netdev_priv(dev);
>
> - stats->tx_bytes = atomic_long_read(&priv->tx_bytes);
> - stats->tx_packets = atomic_long_read(&priv->tx_packets);
> - stats->tx_dropped = atomic_long_read(&priv->tx_dropped);
> - stats->rx_bytes = atomic_long_read(&priv->rx_bytes);
> - stats->rx_packets = atomic_long_read(&priv->rx_packets);
> - stats->rx_errors = atomic_long_read(&priv->rx_errors);
> + stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes);
> + stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
> + stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
> + stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes);
> + stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
> + stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors);
> +
> }
>
> static const struct net_device_ops l2tp_eth_netdev_ops = {
This is not the right way to fix this.
1. shouldn't be using atomic's for network counters, look at other network devices.
2. should be using u64_stats_fetch api to handle 64 bit counters.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] l2tp: cast l2tp traffic counter to unsigned
2017-06-09 22:16 ` Stephen Hemminger
@ 2017-06-10 0:29 ` Eric Dumazet
2017-06-10 20:13 ` David Miller
0 siblings, 1 reply; 6+ messages in thread
From: Eric Dumazet @ 2017-06-10 0:29 UTC (permalink / raw)
To: Stephen Hemminger; +Cc: Dominik Heidler, netdev, linux-kernel, Tom Parkin
On Fri, 2017-06-09 at 15:16 -0700, Stephen Hemminger wrote:
> On Fri, 9 Jun 2017 16:29:47 +0200
> Dominik Heidler <dheidler@suse.de> wrote:
>
> > This fixes a counter problem on 32bit systems:
> > When the rx_bytes counter reached 2 GiB, it jumpd to (2^64 Bytes - 2GiB) Bytes.
> >
> > rtnl_link_stats64 has __u64 type and atomic_long_read returns
> > atomic_long_t which is signed. Due to the conversation
> > we get an incorrect value on 32bit systems if the MSB of
> > the atomic_long_t value is set.
> >
> > CC: Tom Parkin <tparkin@katalix.com>
> > Fixes: 7b7c0719cd7a ("l2tp: avoid deadlock in l2tp stats update")
> > Signed-off-by: Dominik Heidler <dheidler@suse.de>
> > ---
> > net/l2tp/l2tp_eth.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
> > index 8b21af7321b9..668a75e002e9 100644
> > --- a/net/l2tp/l2tp_eth.c
> > +++ b/net/l2tp/l2tp_eth.c
> > @@ -114,12 +114,13 @@ static void l2tp_eth_get_stats64(struct net_device *dev,
> > {
> > struct l2tp_eth *priv = netdev_priv(dev);
> >
> > - stats->tx_bytes = atomic_long_read(&priv->tx_bytes);
> > - stats->tx_packets = atomic_long_read(&priv->tx_packets);
> > - stats->tx_dropped = atomic_long_read(&priv->tx_dropped);
> > - stats->rx_bytes = atomic_long_read(&priv->rx_bytes);
> > - stats->rx_packets = atomic_long_read(&priv->rx_packets);
> > - stats->rx_errors = atomic_long_read(&priv->rx_errors);
> > + stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes);
> > + stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
> > + stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
> > + stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes);
> > + stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
> > + stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors);
> > +
> > }
> >
> > static const struct net_device_ops l2tp_eth_netdev_ops = {
>
> This is not the right way to fix this.
>
> 1. shouldn't be using atomic's for network counters, look at other network devices.
>
> 2. should be using u64_stats_fetch api to handle 64 bit counters.
But they do not want 64bit counters, and not per cpu counters for a
driver handling few packets per second.
Just use native size of "unsigned long".
We use the same atomic_long_t for (struct netdev)->rx_dropped,
tx_dropped & rx_nohandler
So I guess same fix is needed in dev_get_stats()
diff --git a/net/core/dev.c b/net/core/dev.c
index 54bb8d99d26afcc1a9c5a56f1e8c2d1f6e06db98..1a66a8761f9a579c9bf6b6ab5b1415770adcf76b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7785,9 +7785,9 @@ struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
} else {
netdev_stats_to_stats64(storage, &dev->stats);
}
- storage->rx_dropped += atomic_long_read(&dev->rx_dropped);
- storage->tx_dropped += atomic_long_read(&dev->tx_dropped);
- storage->rx_nohandler += atomic_long_read(&dev->rx_nohandler);
+ storage->rx_dropped += (unsigned long)atomic_long_read(&dev->rx_dropped);
+ storage->tx_dropped += (unsigned long)atomic_long_read(&dev->tx_dropped);
+ storage->rx_nohandler += (unsigned long)atomic_long_read(&dev->rx_nohandler);
return storage;
}
EXPORT_SYMBOL(dev_get_stats);
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] l2tp: cast l2tp traffic counter to unsigned
2017-06-10 0:29 ` Eric Dumazet
@ 2017-06-10 20:13 ` David Miller
2017-06-27 14:02 ` [PATCH net] net: prevent sign extension in dev_get_stats() Eric Dumazet
0 siblings, 1 reply; 6+ messages in thread
From: David Miller @ 2017-06-10 20:13 UTC (permalink / raw)
To: eric.dumazet; +Cc: stephen, dheidler, netdev, linux-kernel, tparkin
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 09 Jun 2017 17:29:11 -0700
> On Fri, 2017-06-09 at 15:16 -0700, Stephen Hemminger wrote:
>> On Fri, 9 Jun 2017 16:29:47 +0200
>> Dominik Heidler <dheidler@suse.de> wrote:
>>
>> > This fixes a counter problem on 32bit systems:
>> > When the rx_bytes counter reached 2 GiB, it jumpd to (2^64 Bytes - 2GiB) Bytes.
>> >
>> > rtnl_link_stats64 has __u64 type and atomic_long_read returns
>> > atomic_long_t which is signed. Due to the conversation
>> > we get an incorrect value on 32bit systems if the MSB of
>> > the atomic_long_t value is set.
>> >
>> > CC: Tom Parkin <tparkin@katalix.com>
>> > Fixes: 7b7c0719cd7a ("l2tp: avoid deadlock in l2tp stats update")
>> > Signed-off-by: Dominik Heidler <dheidler@suse.de>
>> > ---
>> > net/l2tp/l2tp_eth.c | 13 +++++++------
>> > 1 file changed, 7 insertions(+), 6 deletions(-)
>> >
>> > diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
>> > index 8b21af7321b9..668a75e002e9 100644
>> > --- a/net/l2tp/l2tp_eth.c
>> > +++ b/net/l2tp/l2tp_eth.c
>> > @@ -114,12 +114,13 @@ static void l2tp_eth_get_stats64(struct net_device *dev,
>> > {
>> > struct l2tp_eth *priv = netdev_priv(dev);
>> >
>> > - stats->tx_bytes = atomic_long_read(&priv->tx_bytes);
>> > - stats->tx_packets = atomic_long_read(&priv->tx_packets);
>> > - stats->tx_dropped = atomic_long_read(&priv->tx_dropped);
>> > - stats->rx_bytes = atomic_long_read(&priv->rx_bytes);
>> > - stats->rx_packets = atomic_long_read(&priv->rx_packets);
>> > - stats->rx_errors = atomic_long_read(&priv->rx_errors);
>> > + stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes);
>> > + stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
>> > + stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
>> > + stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes);
>> > + stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
>> > + stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors);
>> > +
>> > }
>> >
>> > static const struct net_device_ops l2tp_eth_netdev_ops = {
>>
>> This is not the right way to fix this.
>>
>> 1. shouldn't be using atomic's for network counters, look at other network devices.
>>
>> 2. should be using u64_stats_fetch api to handle 64 bit counters.
>
> But they do not want 64bit counters, and not per cpu counters for a
> driver handling few packets per second.
>
> Just use native size of "unsigned long".
Ahh yeah, indeed. I've applied this l2tp patch, therefore.
> We use the same atomic_long_t for (struct netdev)->rx_dropped,
> tx_dropped & rx_nohandler
>
> So I guess same fix is needed in dev_get_stats()
Looks like it, I'll apply a formal submission of this.
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH net] net: prevent sign extension in dev_get_stats()
2017-06-10 20:13 ` David Miller
@ 2017-06-27 14:02 ` Eric Dumazet
2017-06-27 18:51 ` David Miller
0 siblings, 1 reply; 6+ messages in thread
From: Eric Dumazet @ 2017-06-27 14:02 UTC (permalink / raw)
To: David Miller; +Cc: dheidler, netdev
From: Eric Dumazet <edumazet@google.com>
Similar to the fix provided by Dominik Heidler in commit
9b3dc0a17d73 ("l2tp: cast l2tp traffic counter to unsigned")
we need to take care of 32bit kernels in dev_get_stats().
When using atomic_long_read(), we add a 'long' to u64 and
might misinterpret high order bit, unless we cast to unsigned.
Fixes: caf586e5f23ce ("net: add a core netdev->rx_dropped counter")
Fixes: 015f0688f57ca ("net: net: add a core netdev->tx_dropped counter")
Fixes: 6e7333d315a76 ("net: add rx_nohandler stat counter")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jarod Wilson <jarod@redhat.com>
---
Note: I will provide similar other fixes in networking tree.
net/core/dev.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 7243421c9783..91bb55070533 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7783,9 +7783,9 @@ struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
} else {
netdev_stats_to_stats64(storage, &dev->stats);
}
- storage->rx_dropped += atomic_long_read(&dev->rx_dropped);
- storage->tx_dropped += atomic_long_read(&dev->tx_dropped);
- storage->rx_nohandler += atomic_long_read(&dev->rx_nohandler);
+ storage->rx_dropped += (unsigned long)atomic_long_read(&dev->rx_dropped);
+ storage->tx_dropped += (unsigned long)atomic_long_read(&dev->tx_dropped);
+ storage->rx_nohandler += (unsigned long)atomic_long_read(&dev->rx_nohandler);
return storage;
}
EXPORT_SYMBOL(dev_get_stats);
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH net] net: prevent sign extension in dev_get_stats()
2017-06-27 14:02 ` [PATCH net] net: prevent sign extension in dev_get_stats() Eric Dumazet
@ 2017-06-27 18:51 ` David Miller
0 siblings, 0 replies; 6+ messages in thread
From: David Miller @ 2017-06-27 18:51 UTC (permalink / raw)
To: eric.dumazet; +Cc: dheidler, netdev
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 27 Jun 2017 07:02:20 -0700
> From: Eric Dumazet <edumazet@google.com>
>
> Similar to the fix provided by Dominik Heidler in commit
> 9b3dc0a17d73 ("l2tp: cast l2tp traffic counter to unsigned")
> we need to take care of 32bit kernels in dev_get_stats().
>
> When using atomic_long_read(), we add a 'long' to u64 and
> might misinterpret high order bit, unless we cast to unsigned.
>
> Fixes: caf586e5f23ce ("net: add a core netdev->rx_dropped counter")
> Fixes: 015f0688f57ca ("net: net: add a core netdev->tx_dropped counter")
> Fixes: 6e7333d315a76 ("net: add rx_nohandler stat counter")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Jarod Wilson <jarod@redhat.com>
Applied and queued up for -stable, thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2017-06-09 14:29 [PATCH] l2tp: cast l2tp traffic counter to unsigned Dominik Heidler
2017-06-09 22:16 ` Stephen Hemminger
2017-06-10 0:29 ` Eric Dumazet
2017-06-10 20:13 ` David Miller
2017-06-27 14:02 ` [PATCH net] net: prevent sign extension in dev_get_stats() Eric Dumazet
2017-06-27 18:51 ` David Miller
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