Re: [PATCH net-next v17 01/14] netdev: add netdev_rx_queue_restart()

On Tue, 30 Jul 2024 02:26:05 +0000, Mina Almasry almasrymina@google.com wrote:

Add netdev_rx_queue_restart() function to netdev_rx_queue.h

Can you say more? As far as I understand, we just release the buffer submitted to the rx ring and get a new page pool.

But I personally feel that the interface here is a bit too complicated. In particular, we also need to copy the rx struct memory, which means it is a dangerous operation for many pointers.

Thanks.

Signed-off-by: David Wei dw@davidwei.uk Signed-off-by: Mina Almasry almasrymina@google.com Reviewed-by: Pavel Begunkov asml.silence@gmail.com Reviewed-by: Jakub Kicinski kuba@kernel.org

---

v17:

• Use ASSERT_RTNL() (Jakub).

v13:

• Add reviewed-by from Pavel (thanks!)
• Fixed comment (Pavel)

v11:

• Fix not checking dev->queue_mgmt_ops (Pavel).
• Fix ndo_queue_mem_free call that passed the wrong pointer (David).

v9: https://lore.kernel.org/all/20240502045410.3524155-4-dw@davidwei.uk/ (submitted by David).

• fixed SPDX license identifier (Simon).
• Rebased on top of merged queue API definition, and changed implementation to match that.
• Replace rtnl_lock() with rtnl_is_locked() to make it useable from my netlink code where rtnl is already locked.

---

include/net/netdev_rx_queue.h | 3 ++ net/core/Makefile | 1 + net/core/netdev_rx_queue.c | 74 +++++++++++++++++++++++++++++++++++ 3 files changed, 78 insertions(+) create mode 100644 net/core/netdev_rx_queue.c

diff --git a/include/net/netdev_rx_queue.h b/include/net/netdev_rx_queue.h index aa1716fb0e53c..e78ca52d67fbf 100644 --- a/include/net/netdev_rx_queue.h +++ b/include/net/netdev_rx_queue.h @@ -54,4 +54,7 @@ get_netdev_rx_queue_index(struct netdev_rx_queue *queue) return index; } #endif

+int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq);

#endif diff --git a/net/core/Makefile b/net/core/Makefile index 62be9aef25285..f82232b358a2c 100644 --- a/net/core/Makefile +++ b/net/core/Makefile @@ -19,6 +19,7 @@ obj-$(CONFIG_NETDEV_ADDR_LIST_TEST) += dev_addr_lists_test.o

obj-y += net-sysfs.o obj-y += hotdata.o +obj-y += netdev_rx_queue.o obj-$(CONFIG_PAGE_POOL) += page_pool.o page_pool_user.o obj-$(CONFIG_PROC_FS) += net-procfs.o obj-$(CONFIG_NET_PKTGEN) += pktgen.o diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c new file mode 100644 index 0000000000000..da11720a59830 --- /dev/null +++ b/net/core/netdev_rx_queue.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0-or-later

+#include <linux/netdevice.h> +#include <net/netdev_queues.h> +#include <net/netdev_rx_queue.h>

+int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx) +{

• void *new_mem, *old_mem;
• int err;
• if (!dev->queue_mgmt_ops || !dev->queue_mgmt_ops->ndo_queue_stop ||

•    !dev->queue_mgmt_ops->ndo_queue_mem_free ||
  

•    !dev->queue_mgmt_ops->ndo_queue_mem_alloc ||
  

•    !dev->queue_mgmt_ops->ndo_queue_start)
  

• return -EOPNOTSUPP;
  

• ASSERT_RTNL();
• new_mem = kvzalloc(dev->queue_mgmt_ops->ndo_queue_mem_size, GFP_KERNEL);
• if (!new_mem)

• return -ENOMEM;
  

• old_mem = kvzalloc(dev->queue_mgmt_ops->ndo_queue_mem_size, GFP_KERNEL);
• if (!old_mem) {

• err = -ENOMEM;
  

• goto err_free_new_mem;
  

• }
• err = dev->queue_mgmt_ops->ndo_queue_mem_alloc(dev, new_mem, rxq_idx);
• if (err)

• goto err_free_old_mem;
  

• err = dev->queue_mgmt_ops->ndo_queue_stop(dev, old_mem, rxq_idx);
• if (err)

• goto err_free_new_queue_mem;
  

• err = dev->queue_mgmt_ops->ndo_queue_start(dev, new_mem, rxq_idx);
• if (err)

• goto err_start_queue;
  

• dev->queue_mgmt_ops->ndo_queue_mem_free(dev, old_mem);
• kvfree(old_mem);
• kvfree(new_mem);
• return 0;

+err_start_queue:

• /* Restarting the queue with old_mem should be successful as we haven't

• * changed any of the queue configuration, and there is not much we can
  

• * do to recover from a failure here.
  

• *
  

• * WARN if we fail to recover the old rx queue, and at least free
  

• * old_mem so we don't also leak that.
  

• */
  

• if (dev->queue_mgmt_ops->ndo_queue_start(dev, old_mem, rxq_idx)) {

• WARN(1,
  

•      "Failed to restart old queue in error path. RX queue %d may be unhealthy.",
  

•      rxq_idx);
  

• dev->queue_mgmt_ops->ndo_queue_mem_free(dev, old_mem);
  

• }

+err_free_new_queue_mem:

• dev->queue_mgmt_ops->ndo_queue_mem_free(dev, new_mem);

+err_free_old_mem:

• kvfree(old_mem);

+err_free_new_mem:

• kvfree(new_mem);
• return err;

+}

2.46.0.rc1.232.g9752f9e123-goog