From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B30853212 for ; Tue, 7 Feb 2023 13:00:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D3CCC433D2; Tue, 7 Feb 2023 13:00:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1675774818; bh=N1QxBAHhsHFplgwgAjDkBS/fDJXxoD5O3wPt2CUzpCA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PXmv1IfgtwIu6xumZXAAqKKOUU6gZLGEZtBM8NpkHQvtOAnScfk3rjyZ5T9cvNbiZ hhaqC1fCxW7DPIgY//aWSiHeD9qA2z446dSBKIfy1oGHrgzr+wjCdDDU4eTAG4CmhO 8+Wss638dpp34vPVCuo/me6obt38UQ+5EkVxQmBM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Magnus Karlsson , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Camelia Groza , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 043/208] dpaa_eth: execute xdp_do_flush() before napi_complete_done() Date: Tue, 7 Feb 2023 13:54:57 +0100 Message-Id: <20230207125636.243686697@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230207125634.292109991@linuxfoundation.org> References: <20230207125634.292109991@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Magnus Karlsson [ Upstream commit b534013798b77f81a36f36dafd59bab9de837619 ] Make sure that xdp_do_flush() is always executed before napi_complete_done(). This is important for two reasons. First, a redirect to an XSKMAP assumes that a call to xdp_do_redirect() from napi context X on CPU Y will be followed by a xdp_do_flush() from the same napi context and CPU. This is not guaranteed if the napi_complete_done() is executed before xdp_do_flush(), as it tells the napi logic that it is fine to schedule napi context X on another CPU. Details from a production system triggering this bug using the veth driver can be found following the first link below. The second reason is that the XDP_REDIRECT logic in itself relies on being inside a single NAPI instance through to the xdp_do_flush() call for RCU protection of all in-kernel data structures. Details can be found in the second link below. Fixes: a1e031ffb422 ("dpaa_eth: add XDP_REDIRECT support") Signed-off-by: Magnus Karlsson Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20221220185903.1105011-1-sbohrer@cloudflare.com Link: https://lore.kernel.org/all/20210624160609.292325-1-toke@redhat.com/ Acked-by: Camelia Groza Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c index fc68a32ce2f7..d8fb7d4ebd51 100644 --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c @@ -2400,6 +2400,9 @@ static int dpaa_eth_poll(struct napi_struct *napi, int budget) cleaned = qman_p_poll_dqrr(np->p, budget); + if (np->xdp_act & XDP_REDIRECT) + xdp_do_flush(); + if (cleaned < budget) { napi_complete_done(napi, cleaned); qman_p_irqsource_add(np->p, QM_PIRQ_DQRI); @@ -2407,9 +2410,6 @@ static int dpaa_eth_poll(struct napi_struct *napi, int budget) qman_p_irqsource_add(np->p, QM_PIRQ_DQRI); } - if (np->xdp_act & XDP_REDIRECT) - xdp_do_flush(); - return cleaned; } -- 2.39.0