netdev - Re: [PATCH net] net/ipv4: Use non-atomic allocation of udp offloads structure instance

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Date:	Wed, 29 Jan 2014 08:20:11 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Or Gerlitz <ogerlitz@...lanox.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	dan.carpenter@...cle.com
Subject: Re: [PATCH net] net/ipv4: Use non-atomic allocation of udp offloads
 structure instance

On Wed, 2014-01-29 at 18:08 +0200, Or Gerlitz wrote:
> Since udp_add_offload() can be called from non-sleepable context e.g
> under this call tree from the vxlan driver use case:
> 
>   vxlan_socket_create() <-- holds the spinlock
>   -> vxlan_notify_add_rx_port()
>      -> udp_add_offload()  <-- schedules
> 
> we should allocate the udp_offloads structure in atomic manner.
> 
> Fixes: b582ef0 ('net: Add GRO support for UDP encapsulating protocols')
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Or Gerlitz <ogerlitz@...lanox.com>
> ---
>  net/ipv4/udp_offload.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
> index 25f5cee..2ffea6f 100644
> --- a/net/ipv4/udp_offload.c
> +++ b/net/ipv4/udp_offload.c
> @@ -101,7 +101,7 @@ out:
>  int udp_add_offload(struct udp_offload *uo)
>  {
>  	struct udp_offload_priv __rcu **head = &udp_offload_base;
> -	struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_KERNEL);
> +	struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
>  
>  	if (!new_offload)
>  		return -ENOMEM;

Could you also fix all the rcu_dereference() calls ?

Try CONFIG_PROVE_RCU=y



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