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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org (open list) Subject: [PATCH net-next] net: ibm: emac: Clear MAL descriptors without memset Date: Sat, 16 May 2026 20:36:21 -0700 Message-ID: <20260517033621.1839397-1-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Clear MAL descriptor rings with explicit field stores instead of memset(). The descriptor rings are carved from MAL coherent DMA memory, which may be mapped uncached on 32-bit powerpc. The optimized memset() path can use dcbz there and trigger an alignment warning. The skb tracking arrays remain ordinary CPU memory and still use memset(). Assisted-by: Codex:GPT-5.5 Signed-off-by: Rosen Penev --- drivers/net/ethernet/ibm/emac/core.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c index 1fd7cb50c568..7ab5c944f5de 100644 --- a/drivers/net/ethernet/ibm/emac/core.c +++ b/drivers/net/ethernet/ibm/emac/core.c @@ -1161,6 +1161,17 @@ static void emac_clean_rx_ring(struct emac_instance *dev) } } +static void emac_clear_mal_desc(struct mal_descriptor *desc, int count) +{ + int i; + + for (i = 0; i < count; i++) { + desc[i].ctrl = 0; + desc[i].data_len = 0; + desc[i].data_ptr = 0; + } +} + static int __emac_prepare_rx_skb(struct sk_buff *skb, struct emac_instance *dev, int slot) { @@ -3121,8 +3132,8 @@ static int emac_probe(struct platform_device *ofdev) DBG(dev, "rx_desc %p" NL, dev->rx_desc); /* Clean rings */ - memset(dev->tx_desc, 0, NUM_TX_BUFF * sizeof(struct mal_descriptor)); - memset(dev->rx_desc, 0, NUM_RX_BUFF * sizeof(struct mal_descriptor)); + emac_clear_mal_desc(dev->tx_desc, NUM_TX_BUFF); + emac_clear_mal_desc(dev->rx_desc, NUM_RX_BUFF); memset(dev->tx_skb, 0, NUM_TX_BUFF * sizeof(struct sk_buff *)); memset(dev->rx_skb, 0, NUM_RX_BUFF * sizeof(struct sk_buff *)); -- 2.54.0