From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792523211; b=iS9hbRF6gImbV3ETlx1ikT/p71X/O2heyr4UFH98bdbcOqYwRaaGG5/9sg8bHE3jkuww MOzxbj317QPemR3P+p822FlPTIVgZri51Ggt9NC2NEiilPqnEBN5e6Ei784kR3Z/lX5V9 0YC5xdcx44gCEXklLFj48Hc1yF0lw4OFUC9ojFbwWsxDXfY8FCsZHteQt9qzPV73dJNk7 s9U0UN71ojraa+vI6s+bsH110qzBOSaKH8nTCia1Qzl0rdo+KW/L/cnUgrUVle2nCMmFJ LGhEf/WeV9OZ4Ib2H+737wRBay0+wWDyZoE3doNN1Iukh6uCRfgP55PrCYRLeMIKEXA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792523211; h=Received:DKIM-Signature:From:To:Cc:Subject:In-Reply-To:References: Date:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding; bh=fWHcLGrpwXfqLXhaJj0WaQH5QqKgXLOGytFJYtpDAYM=; b=NDne5cvk7riCcRBH9ZmZhyb/gbFRLj5Km3NkKcPio+YmhSAif6xVb5jumnVmgWRfH543 nId8K2/Bpp4NRxDD3GcpnZ7+Sa+lCdNvt4ZFXLrmklHcBPqIBsLpyEeQXZXNTtrJFDR0N lEpU0YjtmRjopIxxZX6cse/ObaGxCx0mW67ryUJVfOatwZtIN2FIXrt21cJBW7eVEcxhB 9jyqrheOLPhht7VkP9tmSEbk3RxOqodW0Y8hHhoQanUvSiBJhRCZSvuPB65ma9kly3+qq CmsDlJ/hNJr2zU1sp8DEshyTnM63kYrh1hxCvM0s28E3QBEgagX9Z5Hd9WNDruLvphw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=cvBMvhO5; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E0CA6606A32A; Tue, 20 Oct 2026 19:06:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=cvBMvhO5 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2DDBF1F000C9; Tue, 20 Oct 2026 19:06:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792523210; bh=fWHcLGrpwXfqLXhaJj0WaQH5QqKgXLOGytFJYtpDAYM=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=cvBMvhO5eGuUCxu+Ci3R7HHSR/hPR5aHl1ZRoZg8zMPbX8SjLF+ymAl9Eb5wsalPU Tj5f77QQBw6aM3Mdzfx9/RAU3nuTYEbfH8/huuiWnIjZOhfXYQHHFGVWayPGOyusMl JMqoKBTTUZZ3q3J+h2Yb7p0f8TOPdAkrurcHRWBRncNfpiwaXQUGlywaV+hztav94S bFGgL6C7hfsPteXZTcd8w7O50hcqcoZQbKz0Nm2dLVFaz1h48sXJuWfu7ac2YbBtXv 6GwvMiLvPykabNa/Gatz69BocBKLcmmo9sVWZrw84AuiPXH+oQ4Kko06Gl3CkGsu0G ZH1yVAC5UDBKg== From: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= To: Dimitri Daskalakis , "David S. Miller" Cc: Alexander Duyck , Jakub Kicinski , kernel-team@meta.com, Andrew Lunn , Eric Dumazet , Paolo Abeni , Simon Horman , Mohsin Bashir , Bobby Eshleman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Dimitri Daskalakis , Dimitri Daskalakis Subject: Re: [PATCH net] eth: fbnic: Correct packet header prefetch In-Reply-To: <20261020172706.1090951-1-dimitri.daskalakis1@gmail.com> References: <20261020172706.1090951-1-dimitri.daskalakis1@gmail.com> Date: Tue, 20 Oct 2026 21:06:47 +0200 Message-ID: <87v76w6vjs.fsf@all.your.base.are.belong.to.us> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Dimitri Daskalakis writes: > From: Dimitri Daskalakis > > The existing call to net_prefetch() fetched a stale address. The data > pointer is not initialized until after the call to xdp_prepare_buff(). > Thus, making the prefetch ineffective. > > Open code the address calcuation to give the prefetch as much time > as possible. > > This was found by manual code inspection. No issues have been observed > from this. > > Fixes: 9064ab485f04 ("eth: fbnic: Prefetch packet headers on Rx") > Signed-off-by: Jakub Kicinski > Signed-off-by: Dimitri Daskalakis Reviewed-by: Bj=C3=B6rn T=C3=B6pel