netdev - Re: [PATCH] pktgen: avoid unused-const-variable warning

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Message-ID: <20250226191723.7891b393@gmx.net>
Date: Wed, 26 Feb 2025 19:17:23 +0100
From: Peter Seiderer <ps.report@....net>
To: Arnd Bergmann <arnd@...nel.org>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
 <pabeni@...hat.com>, Arnd Bergmann <arnd@...db.de>, Simon Horman
 <horms@...nel.org>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pktgen: avoid unused-const-variable warning

Hello Arnd,

On Tue, 25 Feb 2025 09:57:14 +0100, Arnd Bergmann <arnd@...nel.org> wrote:

> From: Arnd Bergmann <arnd@...db.de>
>
> When extra warnings are enable, there are configurations that build
> pktgen without CONFIG_XFRM, which leaves a static const variable unused:
>
> net/core/pktgen.c:213:1: error: unused variable 'F_IPSEC' [-Werror,-Wunused-const-variable]
>   213 | PKT_FLAGS
>       | ^~~~~~~~~
> net/core/pktgen.c:197:2: note: expanded from macro 'PKT_FLAGS'
>   197 |         pf(IPSEC)               /* ipsec on for flows */                \
>       |         ^~~~~~~~~
>
> This could be marked as __maybe_unused, or by making the one use visible
> to the compiler by slightly rearranging the #ifdef blocks. The second
> variant looks slightly nicer here, so use that.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  net/core/pktgen.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/net/core/pktgen.c b/net/core/pktgen.c
> index 55064713223e..402e01a2ce19 100644
> --- a/net/core/pktgen.c
> +++ b/net/core/pktgen.c
> @@ -158,9 +158,7 @@
>  #include <net/udp.h>
>  #include <net/ip6_checksum.h>
>  #include <net/addrconf.h>
> -#ifdef CONFIG_XFRM
>  #include <net/xfrm.h>
> -#endif

This ifdef/endif can be kept (as the xfrm stuff is still not used)...

>  #include <net/netns/generic.h>
>  #include <asm/byteorder.h>
>  #include <linux/rcupdate.h>
> @@ -2363,13 +2361,13 @@ static inline int f_pick(struct pktgen_dev *pkt_dev)
>  }
>
>
> -#ifdef CONFIG_XFRM
>  /* If there was already an IPSEC SA, we keep it as is, else
>   * we go look for it ...
>  */
>  #define DUMMY_MARK 0

A now unused define...

>  static void get_ipsec_sa(struct pktgen_dev *pkt_dev, int flow)
>  {
> +#ifdef CONFIG_XFRM
>  	struct xfrm_state *x = pkt_dev->flows[flow].x;
>  	struct pktgen_net *pn = net_generic(dev_net(pkt_dev->odev), pg_net_id);

Maybe better this way here?

	const u32 dummy_mark = 0;

>  	if (!x) {
> @@ -2395,11 +2393,10 @@ static void get_ipsec_sa(struct pktgen_dev *pkt_dev, int flow)
>  		}
>
>  	}
> -}
>  #endif
> +}
>  static void set_cur_queue_map(struct pktgen_dev *pkt_dev)
>  {
> -
>  	if (pkt_dev->flags & F_QUEUE_MAP_CPU)
>  		pkt_dev->cur_queue_map = smp_processor_id();
>
> @@ -2574,10 +2571,8 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
>  				pkt_dev->flows[flow].flags |= F_INIT;
>  				pkt_dev->flows[flow].cur_daddr =
>  				    pkt_dev->cur_daddr;
> -#ifdef CONFIG_XFRM
>  				if (pkt_dev->flags & F_IPSEC)
>  					get_ipsec_sa(pkt_dev, flow);
> -#endif
>  				pkt_dev->nflows++;
>  			}
>  		}

Otherwise works as expected, you can add my (with or without the suggested
changes)

Reviewed-by: Peter Seiderer <ps.report@....net>

Regards,
Peter