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 6A5BCFBE8 for ; Thu, 1 Jun 2023 13:27:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8726CC433EF; Thu, 1 Jun 2023 13:27:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685626043; bh=l1+wkJBql6UtkIYpV7h81XObR2QkUArtaDh2lgwwvy0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z3DprAeuHwSweg2vojZsOetFL8gXUzKpv5ecYYvb8z07SJ072vuDrFRn050yWa33D JsK9+zsdApxIdWCrUkxHTOn4AX2ISOxEkE85w2F0UzmUo9EX3kgjpzASzi+hEITbXK QXTUfrHajF8tScN1T/DUzC7qpVO3PMoAgqCxHXcQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Shenwei Wang , Wei Fang , "David S. Miller" , Sasha Levin Subject: [PATCH 6.3 18/45] net: fec: add dma_wmb to ensure correct descriptor values Date: Thu, 1 Jun 2023 14:21:14 +0100 Message-Id: <20230601131939.544331582@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230601131938.702671708@linuxfoundation.org> References: <20230601131938.702671708@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: Shenwei Wang [ Upstream commit 9025944fddfed5966c8f102f1fe921ab3aee2c12 ] Two dma_wmb() are added in the XDP TX path to ensure proper ordering of descriptor and buffer updates: 1. A dma_wmb() is added after updating the last BD to make sure the updates to rest of the descriptor are visible before transferring ownership to FEC. 2. A dma_wmb() is also added after updating the bdp to ensure these updates are visible before updating txq->bd.cur. 3. Start the xmit of the frame immediately right after configuring the tx descriptor. Fixes: 6d6b39f180b8 ("net: fec: add initial XDP support") Signed-off-by: Shenwei Wang Reviewed-by: Wei Fang Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/ethernet/freescale/fec_main.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 577d94821b3e7..38e5b5abe067c 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -3834,6 +3834,11 @@ static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep, index = fec_enet_get_bd_index(last_bdp, &txq->bd); txq->tx_skbuff[index] = NULL; + /* Make sure the updates to rest of the descriptor are performed before + * transferring ownership. + */ + dma_wmb(); + /* Send it on its way. Tell FEC it's ready, interrupt when done, * it's the last BD of the frame, and to put the CRC on the end. */ @@ -3843,8 +3848,14 @@ static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep, /* If this was the last BD in the ring, start at the beginning again. */ bdp = fec_enet_get_nextdesc(last_bdp, &txq->bd); + /* Make sure the update to bdp are performed before txq->bd.cur. */ + dma_wmb(); + txq->bd.cur = bdp; + /* Trigger transmission start */ + writel(0, txq->bd.reg_desc_active); + return 0; } @@ -3873,12 +3884,6 @@ static int fec_enet_xdp_xmit(struct net_device *dev, sent_frames++; } - /* Make sure the update to bdp and tx_skbuff are performed. */ - wmb(); - - /* Trigger transmission start */ - writel(0, txq->bd.reg_desc_active); - __netif_tx_unlock(nq); return sent_frames; -- 2.39.2