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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org (open list) Subject: [PATCH 03/10] net: emac: use DMA-specific and SMP memory barriers Date: Mon, 29 Jun 2026 21:16:27 -0700 Message-ID: <20260630041634.284127-4-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260630041634.284127-1-rosenp@gmail.com> References: <20260630041634.284127-1-rosenp@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Replace generic wmb()/mb() barriers with more specific variants: - dma_wmb() for ordering descriptor field writes before hardware ownership bit (ctrl) hand-off in TX/RX paths - dma_rmb() for ordering descriptor ctrl read after ownership observation in the RX poll path - smp_wmb() for CPU-to-CPU ordering (link_polling flag, platform_set_drvdata visibility) - dma_rmb() for the RX descriptor ownership transfer read Assisted-by: opencode:big-pickle Signed-off-by: Rosen Penev --- drivers/net/ethernet/ibm/emac/core.c | 16 ++++++++-------- drivers/net/ethernet/ibm/emac/mal.c | 2 +- drivers/net/ethernet/ibm/emac/rgmii.c | 2 +- drivers/net/ethernet/ibm/emac/tah.c | 2 +- drivers/net/ethernet/ibm/emac/zmii.c | 4 ++-- 5 files changed, 13 insertions(+), 13 deletions(-) diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c index 1d46cf6c2c12..5e7b85d28bde 100644 --- a/drivers/net/ethernet/ibm/emac/core.c +++ b/drivers/net/ethernet/ibm/emac/core.c @@ -1185,7 +1185,7 @@ __emac_prepare_rx_skb(struct sk_buff *skb, struct emac_instance *dev, int slot) dev->rx_desc[slot].data_ptr = dma_map_single(&dev->ofdev->dev, skb->data - NET_IP_ALIGN, dev->rx_sync_size, DMA_FROM_DEVICE) + NET_IP_ALIGN; - wmb(); + dma_wmb(); dev->rx_desc[slot].ctrl = MAL_RX_CTRL_EMPTY | (slot == (NUM_RX_BUFF - 1) ? MAL_RX_CTRL_WRAP : 0); @@ -1263,7 +1263,7 @@ static int emac_open(struct net_device *ndev) link_poll_interval = PHY_POLL_LINK_OFF; } dev->link_polling = 1; - wmb(); + smp_wmb(); schedule_delayed_work(&dev->link_work, link_poll_interval); emac_print_link_status(dev); } else @@ -1464,7 +1464,7 @@ static netdev_tx_t emac_start_xmit(struct sk_buff *skb, struct net_device *ndev) skb->data, len, DMA_TO_DEVICE); dev->tx_desc[slot].data_len = (u16) len; - wmb(); + dma_wmb(); dev->tx_desc[slot].ctrl = ctrl; return emac_xmit_finish(dev, len); @@ -1560,7 +1560,7 @@ emac_start_xmit_sg(struct sk_buff *skb, struct net_device *ndev) /* Send the packet out */ if (dev->tx_slot == NUM_TX_BUFF - 1) ctrl |= MAL_TX_CTRL_WRAP; - wmb(); + dma_wmb(); dev->tx_desc[dev->tx_slot].ctrl = ctrl; dev->tx_slot = (slot + 1) % NUM_TX_BUFF; @@ -1671,7 +1671,7 @@ static inline void emac_recycle_rx_skb(struct emac_instance *dev, int slot, DMA_FROM_DEVICE); dev->rx_desc[slot].data_len = 0; - wmb(); + dma_wmb(); dev->rx_desc[slot].ctrl = MAL_RX_CTRL_EMPTY | (slot == (NUM_RX_BUFF - 1) ? MAL_RX_CTRL_WRAP : 0); } @@ -1754,7 +1754,7 @@ static int emac_poll_rx(void *param, int budget) break; skb = dev->rx_skb[slot]; - mb(); + dma_rmb(); len = dev->rx_desc[slot].data_len; if (unlikely(!MAL_IS_SINGLE_RX(ctrl))) @@ -1845,7 +1845,7 @@ static int emac_poll_rx(void *param, int budget) } if (unlikely(budget && test_bit(MAL_COMMAC_RX_STOPPED, &dev->commac.flags))) { - mb(); + dma_rmb(); if (!(dev->rx_desc[slot].ctrl & MAL_RX_CTRL_EMPTY)) { DBG2(dev, "rx restart" NL); received = 0; @@ -3167,7 +3167,7 @@ static int emac_probe(struct platform_device *ofdev) /* Set our drvdata last as we don't want them visible until we are * fully initialized */ - wmb(); + smp_wmb(); platform_set_drvdata(ofdev, dev); printk(KERN_INFO "%s: EMAC-%d %pOF, MAC %pM\n", diff --git a/drivers/net/ethernet/ibm/emac/mal.c b/drivers/net/ethernet/ibm/emac/mal.c index 4025bc36ae16..99615c8a6c3e 100644 --- a/drivers/net/ethernet/ibm/emac/mal.c +++ b/drivers/net/ethernet/ibm/emac/mal.c @@ -691,7 +691,7 @@ static int mal_probe(struct platform_device *ofdev) mal->num_tx_chans, mal->num_rx_chans); /* Advertise this instance to the rest of the world */ - wmb(); + smp_wmb(); platform_set_drvdata(ofdev, mal); return 0; diff --git a/drivers/net/ethernet/ibm/emac/rgmii.c b/drivers/net/ethernet/ibm/emac/rgmii.c index b544dd8633b7..093aa4f129e3 100644 --- a/drivers/net/ethernet/ibm/emac/rgmii.c +++ b/drivers/net/ethernet/ibm/emac/rgmii.c @@ -255,7 +255,7 @@ static int rgmii_probe(struct platform_device *ofdev) ofdev->dev.of_node, (dev->flags & EMAC_RGMII_FLAG_HAS_MDIO) ? "" : "out"); - wmb(); + smp_wmb(); platform_set_drvdata(ofdev, dev); return 0; diff --git a/drivers/net/ethernet/ibm/emac/tah.c b/drivers/net/ethernet/ibm/emac/tah.c index ed07532aaf85..077da56fa449 100644 --- a/drivers/net/ethernet/ibm/emac/tah.c +++ b/drivers/net/ethernet/ibm/emac/tah.c @@ -112,7 +112,7 @@ static int tah_probe(struct platform_device *ofdev) tah_reset(ofdev); printk(KERN_INFO "TAH %pOF initialized\n", ofdev->dev.of_node); - wmb(); + smp_wmb(); return 0; } diff --git a/drivers/net/ethernet/ibm/emac/zmii.c b/drivers/net/ethernet/ibm/emac/zmii.c index a3839cf02ec4..5144ee94a7d2 100644 --- a/drivers/net/ethernet/ibm/emac/zmii.c +++ b/drivers/net/ethernet/ibm/emac/zmii.c @@ -258,8 +258,8 @@ static int zmii_probe(struct platform_device *ofdev) /* Disable all inputs by default */ out_be32(&dev->base->fer, 0); - printk(KERN_INFO "ZMII %pOF initialized\n", ofdev->dev.of_node); - wmb(); + dev_info(&ofdev->dev, "ZMII initialized\n"); + smp_wmb(); platform_set_drvdata(ofdev, dev); return 0; -- 2.54.0