Patchwork vmxnet3 driver broken since 3.0?

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Submitter Alessandro Salvatori
Date Dec. 12, 2011, 7:54 a.m.
Message ID <CAJeBh4uCzUTFpQxf-rcXWkCUy9UEryiaz8akiDovLqU2C8WQEg@mail.gmail.com>
Download mbox | patch
Permalink /patch/130666/
State Not Applicable
Delegated to: David Miller
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Comments

Alessandro Salvatori - Dec. 12, 2011, 7:54 a.m.
I guess this is the change that was introduced in 3.0 and that breaks vmxnet3:

commit 55513fb4281464e97aa1ff2b9c906ca5aed917c5
Author: Tom Herbert <therbert@google.com>
Date:   Mon Oct 18 17:55:58 2010 +0000

    net: fail alloc_netdev_mq if queue count < 1

    In alloc_netdev_mq fail if requested queue_count < 1.

    Signed-off-by: Tom Herbert <therbert@google.com>
    Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>

                /* ensure 32-byte alignment of private area */

thanks!
-Alessandro-
 Here i am, A young man,
 A crashing computer program,
 Here is a pen, write out my name...

(from: The Servant - Orchestra)



On Sun, Dec 11, 2011 at 14:38, Zbigniew Luszpinski <zbiggy@o2.pl> wrote:
> Alessandro Salvatori <sandr8 <at> gmail.com> writes:
>> haven't had a chance to try the one from the 3.2 release candidates yet.
>
> In 3.2-rc5 is still broken. Exactly the same error you get. :(
> Someone introduced a change since kernel 3.0 which broke vmxnet3 driver. And
> this breaking change continues in kernel 3.1 and 3.2-rc5 so it seems it will not
> go away. :(
>
> have a nice day,
> Zbigniew Luszpinski
>
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stephen hemminger - Dec. 12, 2011, 5:05 p.m.
On Sun, 11 Dec 2011 23:54:50 -0800
Alessandro Salvatori <sandr8@gmail.com> wrote:

> I guess this is the change that was introduced in 3.0 and that breaks vmxnet3:
> 
> commit 55513fb4281464e97aa1ff2b9c906ca5aed917c5
> Author: Tom Herbert <therbert@google.com>
> Date:   Mon Oct 18 17:55:58 2010 +0000
> 
>     net: fail alloc_netdev_mq if queue count < 1
> 
>     In alloc_netdev_mq fail if requested queue_count < 1.
> 
>     Signed-off-by: Tom Herbert <therbert@google.com>
>     Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
>     Signed-off-by: David S. Miller <davem@davemloft.net>
> 
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 04972a4..f44d29a 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -5511,6 +5511,12 @@ struct net_device *alloc_netdev_mq(int
> sizeof_priv, const char *name,
> 
>         BUG_ON(strlen(name) >= sizeof(dev->name));
> 
> +       if (queue_count < 1) {
> +               pr_err("alloc_netdev: Unable to allocate device "
> +                      "with zero queues.\n");
> +               return NULL;
> +       }
> +
>         alloc_size = sizeof(struct net_device);
>         if (sizeof_priv) {
>                 /* ensure 32-byte alignment of private area */

Looks like the problem is not in networking core but either in the logic
that computes number of queues.

By default it computes number of queues based on number of cpus.

	num_rx_queues = min(VMXNET3_DEVICE_MAX_RX_QUEUES,
				    (int)num_online_cpus());
	
	num_rx_queues = rounddown_pow_of_two(num_rx_queues);

I suspect something is wrong in the cpu management if it reports
num_online_cpus == 0.



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Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index 04972a4..f44d29a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5511,6 +5511,12 @@  struct net_device *alloc_netdev_mq(int
sizeof_priv, const char *name,

        BUG_ON(strlen(name) >= sizeof(dev->name));

+       if (queue_count < 1) {
+               pr_err("alloc_netdev: Unable to allocate device "
+                      "with zero queues.\n");
+               return NULL;
+       }
+
        alloc_size = sizeof(struct net_device);
        if (sizeof_priv) {