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From: Jakub Kicinski <kuba@kernel.org>
To: Brett A C Sheffield <bacs@librecast.net>
Cc: regressions@lists.linux.dev, netdev@vger.kernel.org,
	stable@vger.kernel.org, davem@davemloft.net, dsahern@kernel.org,
	oscmaes92@gmail.com
Subject: Re: [REGRESSION][BISECTED][PATCH] net: ipv4: fix regression in broadcast routes
Date: Fri, 22 Aug 2025 18:32:50 -0700	[thread overview]
Message-ID: <20250822183250.2a9cb92c@kernel.org> (raw)
In-Reply-To: <20250822165231.4353-4-bacs@librecast.net>

Thanks for bisecting and fixing!

> The broadcast_pmtu.sh selftest provided with the original patch still
> passes with this patch applied.

Hm, yes, AFACT we're losing PMTU discovery but perhaps original commit
wasn't concerned with that. Hopefully Oscar can comment.

On Fri, 22 Aug 2025 16:50:51 +0000 Brett A C Sheffield wrote:
> +		if (type == RTN_BROADCAST) {
> +			/* ensure MTU value for broadcast routes is retained */
> +			ip_dst_init_metrics(&rth->dst, res->fi->fib_metrics);

You need to check if res->fi is actually set before using it

Could you add a selftest / test case for the scenario we broke?
selftests can be in C / bash / Python. If bash hopefully socat
can be used to repro, cause it looks like wakeonlan is not very
widely packaged.

  reply	other threads:[~2025-08-23  1:32 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-22 16:50 [REGRESSION][BISECTED][PATCH] net: ipv4: fix regression in broadcast routes Brett A C Sheffield
2025-08-23  1:32 ` Jakub Kicinski [this message]
2025-08-23 12:13   ` [PATCH v2 1/2] selftests: net: add test for broadcast destination Brett A C Sheffield
2025-08-23 12:13   ` [PATCH v2 2/2] net: ipv4: fix regression in broadcast routes Brett A C Sheffield
2025-08-23 12:24   ` [REGRESSION][BISECTED][PATCH] " Brett Sheffield
2025-08-25  6:02     ` Oscar Maes
2025-08-25  6:09       ` [PATCH net 1/2] net: ipv4: fix regression in local-broadcast routes Oscar Maes
2025-08-25  6:09         ` [PATCH net 2/2] selftests: net: add test for destination in broadcast packets Oscar Maes
2025-08-25  7:03           ` Brett A C Sheffield
2025-08-25 22:56         ` [PATCH net 1/2] net: ipv4: fix regression in local-broadcast routes Jakub Kicinski
2025-08-26 12:11           ` Oscar Maes
2025-08-26 12:17             ` [PATCH net v2 " Oscar Maes
2025-08-26 12:17             ` [PATCH net v2 2/2] selftests: net: add test for destination in broadcast packets Oscar Maes
2025-08-27  1:29               ` Jakub Kicinski
2025-08-28  8:17 ` [REGRESSION][BISECTED][PATCH] net: ipv4: fix regression in broadcast routes kernel test robot
2025-08-28 10:35   ` Paolo Abeni
2025-08-28 10:46     ` Brett A C Sheffield
2025-08-29  2:08       ` Oliver Sang

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