Re: [PATCH v2 net-next] net: Allow SF devices to be used for ZC DMA
From: Jakub Kicinski <kuba@kernel.org>
Date: 2025-07-15 01:11:37
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io-uring, lkml
On Fri, 11 Jul 2025 09:26:34 +0000 Dragos Tatulea wrote:
quoted hunk ↗ jump to hunk
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 5847c20994d3..53aa63d6e5a3 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h@@ -5560,4 +5560,25 @@ extern struct net_device *blackhole_netdev; atomic_long_add((VAL), &(DEV)->stats.__##FIELD) #define DEV_STATS_READ(DEV, FIELD) atomic_long_read(&(DEV)->stats.__##FIELD) +static inline struct device *netdev_get_dma_dev(const struct net_device *dev) +{ + struct device *dma_dev = dev->dev.parent; + + if (!dma_dev) + return NULL; + + /* Common case: dma device is parent device of netdev. */ + if (dma_dev->dma_mask) + return dma_dev; + + /* SF netdevs have an auxdev device as parent, the dma device being the + * grandparent. + */ + dma_dev = dma_dev->parent; + if (dma_dev && dma_dev->dma_mask) + return dma_dev; + + return NULL; +}
LGTM, but we need a better place for this function. netdevice.h is included directly by 1.5k files, and indirectly by probably another 5k. It's not a great place to put random helpers with 2 callers. Maybe net/netdev_rx_queue.h and net/core/netdev_rx_queue.c? I don't think it needs to be a static inline either. -- pw-bot: cr