[PATCH net-next v15 03/14] netdev: support binding dma-buf to netdevice

[Mina Almasry]

On Tue, Jul 9, 2024 at 8:37 AM Taehee Yoo <ap420073 at gmail.com> wrote:
...
> Reproducer:
> ./ncdevmem -f <interface name> -l -p 5201 -v 7 -t 0 -q 2 &
> sleep 10
> modprobe -rv bnxt_en
> killall ncdevmem
>
> I think it's a devmemTCP core bug so this issue would be reproduced
> with other drivers.

Sorry for the late reply. I was out at netdev.

I'm also having trouble reproducing this, not because the bug doesn't
exist, but quirks with my test setup that I need to figure out. AFAICT
this diff should fix the issue. If you have time to confirm, let me
know if it doesn't work for you. It should apply on top of v16:

commit 795b8ff01906d ("fix for release issue")
Author: Mina Almasry <almasrymina at google.com>
Date:   Tue Jul 23 00:18:23 2024 +0000

    fix for release issue

    Change-Id: Ib45a0aa6cba2918db5f7ba535414ffa860911fa4



diff --git a/include/net/devmem.h b/include/net/devmem.h
index 51b25ba193c96..df52526bb516a 100644
--- a/include/net/devmem.h
+++ b/include/net/devmem.h
@@ -68,6 +68,9 @@ net_devmem_bind_dmabuf(struct net_device *dev,
unsigned int dmabuf_fd);
 void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding);
 int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
                                    struct net_devmem_dmabuf_binding *binding);
+
+void dev_dmabuf_uninstall(struct net_device *dev);
+
 struct net_iov *
 net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
 void net_devmem_free_dmabuf(struct net_iov *ppiov);
diff --git a/net/core/dev.c b/net/core/dev.c
index 5882ddc3f8592..7be084e4936e4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -11320,6 +11320,7 @@ void unregister_netdevice_many_notify(struct
list_head *head,
                dev_tcx_uninstall(dev);
                dev_xdp_uninstall(dev);
                bpf_dev_bound_netdev_unregister(dev);
+               dev_dmabuf_uninstall(dev);

                netdev_offload_xstats_disable_all(dev);

diff --git a/net/core/devmem.c b/net/core/devmem.c
index e75057ecfa6de..227bcb1070ec0 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -362,4 +362,20 @@ bool mp_dmabuf_devmem_release_page(struct
page_pool *pool, netmem_ref netmem)
        return false;
 }

+void dev_dmabuf_uninstall(struct net_device *dev)
+{
+       unsigned int i, count = dev->num_rx_queues;
+       struct net_devmem_dmabuf_binding *binding;
+       struct netdev_rx_queue *rxq;
+       unsigned long xa_idx;
+
+       for (i = 0; i < count; i++) {
+               binding = dev->_rx[i].mp_params.mp_priv;
+               if (binding)
+                       xa_for_each(&binding->bound_rxqs, xa_idx, rxq)
+                               if (rxq == &dev->_rx[i])
+                                       xa_erase(&binding->bound_rxqs, xa_idx);
+       }
+}
+
 #endif

-- 
Thanks,
Mina