netdev - Re: [PATCH net-next] net: core: change bool members of struct net

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Date:   Mon, 8 Oct 2018 13:07:51 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] net: core: change bool members of struct
 net_device to bitfield members

On 10/8/18 1:00 PM, Heiner Kallweit wrote:
> bool is good as parameter type or function return type, but if used
> for struct members it consumes more memory than needed.
> Changing the bool members of struct net_device to bitfield members
> allows to decrease the memory footprint of this struct.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> ---
>  include/linux/netdevice.h | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 76603ee13..3d7b8df2e 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1651,10 +1651,6 @@ enum netdev_priv_flags {
>   * 	@dev_port:		Used to differentiate devices that share
>   * 				the same function
>   *	@addr_list_lock:	XXX: need comments on this one
> - *	@uc_promisc:		Counter that indicates promiscuous mode
> - *				has been enabled due to the need to listen to
> - *				additional unicast addresses in a device that
> - *				does not implement ndo_set_rx_mode()
>   *	@uc:			unicast mac addresses
>   *	@mc:			multicast mac addresses
>   *	@dev_addrs:		list of device hw addresses
> @@ -1714,11 +1710,9 @@ enum netdev_priv_flags {
>   *	@link_watch_list:	XXX: need comments on this one
>   *
>   *	@reg_state:		Register/unregister state machine
> - *	@dismantle:		Device is going to be freed
>   *	@rtnl_link_state:	This enum represents the phases of creating
>   *				a new link
>   *
> - *	@needs_free_netdev:	Should unregister perform free_netdev?
>   *	@priv_destructor:	Called from unregister
>   *	@npinfo:		XXX: need comments on this one
>   * 	@nd_net:		Network namespace this network device is inside
> @@ -1758,6 +1752,15 @@ enum netdev_priv_flags {
>   *	@qdisc_tx_busylock: lockdep class annotating Qdisc->busylock spinlock
>   *	@qdisc_running_key: lockdep class annotating Qdisc->running seqcount
>   *
> + *	@uc_promisc:	Counter that indicates promiscuous mode
> + *			has been enabled due to the need to listen to
> + *			additional unicast addresses in a device that
> + *			does not implement ndo_set_rx_mode()

Hi,

I see that all you did is copy/paste that text (above), but I wouldn't call
a single bit a [1-bit] Counter.

thanks,
-- 
~Randy