netdev - Re: [PATCH v2 4/4] net: fix opencoded for_each_and_bit() in __netif_set_xps

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Date:   Fri, 14 Oct 2022 05:38:49 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Yury Norov <yury.norov@...il.com>
Cc:     netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Menglong Dong <imagedong@...cent.com>,
        Kuniyuki Iwashima <kuniyu@...zon.com>,
        Petr Machata <petrm@...dia.com>,
        Guo Ren <guoren@...ux.alibaba.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] net: fix opencoded for_each_and_bit() in
 __netif_set_xps_queue()

On Thu, Oct 13, 2022 at 04:43:48PM -0700, Yury Norov wrote:
> Replace opencoded bitmap traversing and drop unused
> netif_attrmask_next*() functions
> 
> Signed-off-by: Yury Norov <yury.norov@...il.com>

I think you want to document, here, that this fixes a warning.
Additionally, add a Fixes: tag.


> ---
>  include/linux/netdevice.h | 46 ---------------------------------------
>  net/core/dev.c            |  3 +--
>  2 files changed, 1 insertion(+), 48 deletions(-)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 53d738f66159..5db2b6de7308 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -3648,52 +3648,6 @@ static inline bool netif_attr_test_online(unsigned long j,
>  
>  	return (j < nr_bits);
>  }
> -
> -/**
> - *	netif_attrmask_next - get the next CPU/Rx queue in a cpu/Rx queues mask
> - *	@n: CPU/Rx queue index
> - *	@srcp: the cpumask/Rx queue mask pointer
> - *	@nr_bits: number of bits in the bitmask
> - *
> - * Returns >= nr_bits if no further CPUs/Rx queues set.
> - */
> -static inline unsigned int netif_attrmask_next(int n, const unsigned long *srcp,
> -					       unsigned int nr_bits)
> -{
> -	/* n is a prior cpu */
> -	cpu_max_bits_warn(n + 1, nr_bits);
> -
> -	if (srcp)
> -		return find_next_bit(srcp, nr_bits, n + 1);
> -
> -	return n + 1;
> -}
> -
> -/**
> - *	netif_attrmask_next_and - get the next CPU/Rx queue in \*src1p & \*src2p
> - *	@n: CPU/Rx queue index
> - *	@src1p: the first CPUs/Rx queues mask pointer
> - *	@src2p: the second CPUs/Rx queues mask pointer
> - *	@nr_bits: number of bits in the bitmask
> - *
> - * Returns >= nr_bits if no further CPUs/Rx queues set in both.
> - */
> -static inline int netif_attrmask_next_and(int n, const unsigned long *src1p,
> -					  const unsigned long *src2p,
> -					  unsigned int nr_bits)
> -{
> -	/* n is a prior cpu */
> -	cpu_max_bits_warn(n + 1, nr_bits);
> -
> -	if (src1p && src2p)
> -		return find_next_and_bit(src1p, src2p, nr_bits, n + 1);
> -	else if (src1p)
> -		return find_next_bit(src1p, nr_bits, n + 1);
> -	else if (src2p)
> -		return find_next_bit(src2p, nr_bits, n + 1);
> -
> -	return n + 1;
> -}
>  #else
>  static inline int netif_set_xps_queue(struct net_device *dev,
>  				      const struct cpumask *mask,
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 8049e2ff11a5..b0fb592d51da 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2592,8 +2592,7 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
>  		copy = true;
>  
>  	/* allocate memory for queue storage */
> -	for (j = -1; j = netif_attrmask_next_and(j, online_mask, mask, nr_ids),
> -	     j < nr_ids;) {
> +	for_each_and_bit(j, online_mask, mask ? : online_mask, nr_ids) {
>  		if (!new_dev_maps) {
>  			new_dev_maps = kzalloc(maps_sz, GFP_KERNEL);
>  			if (!new_dev_maps)
> -- 
> 2.34.1