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Message-ID: <1f55345f58987dbcfd566e1f61aee55d2c78f788.camel@redhat.com>
Date: Thu, 28 Sep 2023 13:19:48 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Amritha Nambiar <amritha.nambiar@...el.com>, netdev@...r.kernel.org,
kuba@...nel.org
Cc: sridhar.samudrala@...el.com
Subject: Re: [net-next PATCH v3 06/10] netdev-genl: Add netlink framework
functions for napi
On Tue, 2023-09-19 at 15:27 -0700, Amritha Nambiar wrote:
> Implement the netdev netlink framework functions for
> napi support. The netdev structure tracks all the napi
> instances and napi fields. The napi instances and associated
> parameters can be retrieved this way.
>
> Signed-off-by: Amritha Nambiar <amritha.nambiar@...el.com>
> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@...el.com>
> ---
> include/linux/netdevice.h | 2 +
> net/core/dev.c | 4 +-
> net/core/netdev-genl.c | 117 ++++++++++++++++++++++++++++++++++++++++++++-
> 3 files changed, 119 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 69e363918e4b..e7321178dc1a 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -536,6 +536,8 @@ static inline bool napi_complete(struct napi_struct *n)
> return napi_complete_done(n, 0);
> }
>
> +struct napi_struct *napi_by_id(unsigned int napi_id);
> +
> int dev_set_threaded(struct net_device *dev, bool threaded);
>
> /**
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 508b1d799681..ea6b3115ee8b 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -165,7 +165,6 @@ static int netif_rx_internal(struct sk_buff *skb);
> static int call_netdevice_notifiers_extack(unsigned long val,
> struct net_device *dev,
> struct netlink_ext_ack *extack);
> -static struct napi_struct *napi_by_id(unsigned int napi_id);
>
> /*
> * The @dev_base_head list is protected by @dev_base_lock and the rtnl
> @@ -6133,7 +6132,7 @@ bool napi_complete_done(struct napi_struct *n, int work_done)
> EXPORT_SYMBOL(napi_complete_done);
>
> /* must be called under rcu_read_lock(), as we dont take a reference */
> -static struct napi_struct *napi_by_id(unsigned int napi_id)
> +struct napi_struct *napi_by_id(unsigned int napi_id)
> {
> unsigned int hash = napi_id % HASH_SIZE(napi_hash);
> struct napi_struct *napi;
> @@ -6144,6 +6143,7 @@ static struct napi_struct *napi_by_id(unsigned int napi_id)
>
> return NULL;
> }
> +EXPORT_SYMBOL(napi_by_id);
>
> #if defined(CONFIG_NET_RX_BUSY_POLL)
>
> diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
> index 8609884fefe4..6f4ed21ebd15 100644
> --- a/net/core/netdev-genl.c
> +++ b/net/core/netdev-genl.c
> @@ -7,6 +7,7 @@
> #include <net/sock.h>
> #include <net/xdp.h>
> #include <net/netdev_rx_queue.h>
> +#include <net/busy_poll.h>
>
> #include "netdev-genl-gen.h"
>
> @@ -14,6 +15,7 @@ struct netdev_nl_dump_ctx {
> unsigned long ifindex;
> unsigned int rxq_idx;
> unsigned int txq_idx;
> + unsigned int napi_id;
Why you need to add napi_id to the context? don't you need just such
field to do the traversing? e.g. use directly single cb[0]
[...]
> +static int
> +netdev_nl_napi_dump_one(struct net_device *netdev, struct sk_buff *rsp,
> + const struct genl_info *info, unsigned int *start)
> +{
> + struct napi_struct *napi;
> + int err = 0;
> +
> + list_for_each_entry_rcu(napi, &netdev->napi_list, dev_list) {
I'm sorry for the conflicting feedback here, but I think you don't need
any special variant, just 'list_for_each_entry'. This is under rtnl
lock, the list can't change under the hood. Also I think you should get
a RCU splat here when building with CONFIG_PROVE_RCU_LIST.
Cheers,
Paolo
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