From: Jakub Kicinski <kuba@kernel.org>
To: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
kernel@pengutronix.de, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org,
Maxime Chevallier <maxime.chevallier@bootlin.com>
Subject: Re: [PATCH net-next v2 1/1] net: selftests: add PHY-loopback test for bad TCP checksums
Date: Mon, 14 Jul 2025 16:41:42 -0700 [thread overview]
Message-ID: <20250714164142.341e37a2@kernel.org> (raw)
In-Reply-To: <20250711072449.802677-1-o.rempel@pengutronix.de>
On Fri, 11 Jul 2025 09:24:49 +0200 Oleksij Rempel wrote:
> + /* To avoid sparse warnings about operating on
> + * restricted __sum16/__be16 types, explicitly cast the
> + * checksum to a plain u16, perform the manipulation,
> + * and then cast the result back.
> + */
> + csum = (__force u16)thdr->check;
> +
> + /* Mangle the checksum by flipping the LSB. */
> + csum ^= 1;
> + /* If mangling resulted in 0, use the raw value for a
> + * mangled-zero checksum. We use the literal 0xffff
> + * because CSUM_MANGLED_0 has a restricted type.
> + */
> + if (!csum)
> + csum = 0xffff;
> +
> + /* Cast the final integer value back to the restricted
> + * type
> + */
> + thdr->check = (__force __sum16)csum;
Way to manny lines of code for something this simple.
Can csum_add() help you get rid of all these casts and comments?
--
pw-bot: cr
prev parent reply other threads:[~2025-07-14 23:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-11 7:24 [PATCH net-next v2 1/1] net: selftests: add PHY-loopback test for bad TCP checksums Oleksij Rempel
2025-07-12 12:25 ` Simon Horman
2025-07-14 23:41 ` Jakub Kicinski [this message]
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