![Björn Töpel](/assets/img/avatar_default.png)
The AF_XDP socket struct can exist in three different, implicit states: setup, bound and released. Setup is prior the socket has been bound to a device. Bound is when the socket is active for receive and send. Released is when the process/userspace side of the socket is released, but the sock object is still lingering, e.g. when there is a reference to the socket in an XSKMAP after process termination. The Rx fast-path code uses the "dev" member of struct xdp_sock to check whether a socket is bound or relased, and the Tx code uses the struct xdp_umem "xsk_list" member in conjunction with "dev" to determine the state of a socket. However, the transition from bound to released did not tear the socket down in correct order. On the Rx side "dev" was cleared after synchronize_net() making the synchronization useless. On the Tx side, the internal queues were destroyed prior removing them from the "xsk_list". This commit corrects the cleanup order, and by doing so xdp_del_sk_umem() can be simplified and one synchronize_net() can be removed. Fixes:965a990984
("xsk: add support for bind for Rx") Fixes:ac98d8aab6
("xsk: wire upp Tx zero-copy functions") Reported-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Björn Töpel <bjorn.topel@intel.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
405 lines
8.2 KiB
C
405 lines
8.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* XDP user-space packet buffer
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* Copyright(c) 2018 Intel Corporation.
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*/
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#include <linux/init.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task.h>
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#include <linux/uaccess.h>
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#include <linux/slab.h>
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#include <linux/bpf.h>
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#include <linux/mm.h>
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#include <linux/netdevice.h>
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#include <linux/rtnetlink.h>
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#include "xdp_umem.h"
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#include "xsk_queue.h"
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#define XDP_UMEM_MIN_CHUNK_SIZE 2048
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void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
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{
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unsigned long flags;
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spin_lock_irqsave(&umem->xsk_list_lock, flags);
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list_add_rcu(&xs->list, &umem->xsk_list);
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spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
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}
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void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
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{
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unsigned long flags;
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spin_lock_irqsave(&umem->xsk_list_lock, flags);
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list_del_rcu(&xs->list);
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spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
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}
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/* The umem is stored both in the _rx struct and the _tx struct as we do
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* not know if the device has more tx queues than rx, or the opposite.
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* This might also change during run time.
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*/
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static void xdp_reg_umem_at_qid(struct net_device *dev, struct xdp_umem *umem,
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u16 queue_id)
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{
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if (queue_id < dev->real_num_rx_queues)
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dev->_rx[queue_id].umem = umem;
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if (queue_id < dev->real_num_tx_queues)
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dev->_tx[queue_id].umem = umem;
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}
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struct xdp_umem *xdp_get_umem_from_qid(struct net_device *dev,
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u16 queue_id)
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{
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if (queue_id < dev->real_num_rx_queues)
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return dev->_rx[queue_id].umem;
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if (queue_id < dev->real_num_tx_queues)
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return dev->_tx[queue_id].umem;
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return NULL;
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}
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static void xdp_clear_umem_at_qid(struct net_device *dev, u16 queue_id)
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{
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if (queue_id < dev->real_num_rx_queues)
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dev->_rx[queue_id].umem = NULL;
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if (queue_id < dev->real_num_tx_queues)
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dev->_tx[queue_id].umem = NULL;
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}
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int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
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u16 queue_id, u16 flags)
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{
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bool force_zc, force_copy;
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struct netdev_bpf bpf;
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int err = 0;
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force_zc = flags & XDP_ZEROCOPY;
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force_copy = flags & XDP_COPY;
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if (force_zc && force_copy)
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return -EINVAL;
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rtnl_lock();
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if (xdp_get_umem_from_qid(dev, queue_id)) {
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err = -EBUSY;
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goto out_rtnl_unlock;
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}
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xdp_reg_umem_at_qid(dev, umem, queue_id);
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umem->dev = dev;
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umem->queue_id = queue_id;
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if (force_copy)
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/* For copy-mode, we are done. */
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goto out_rtnl_unlock;
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if (!dev->netdev_ops->ndo_bpf ||
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!dev->netdev_ops->ndo_xsk_async_xmit) {
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err = -EOPNOTSUPP;
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goto err_unreg_umem;
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}
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bpf.command = XDP_SETUP_XSK_UMEM;
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bpf.xsk.umem = umem;
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bpf.xsk.queue_id = queue_id;
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err = dev->netdev_ops->ndo_bpf(dev, &bpf);
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if (err)
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goto err_unreg_umem;
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rtnl_unlock();
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dev_hold(dev);
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umem->zc = true;
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return 0;
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err_unreg_umem:
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xdp_clear_umem_at_qid(dev, queue_id);
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if (!force_zc)
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err = 0; /* fallback to copy mode */
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out_rtnl_unlock:
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rtnl_unlock();
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return err;
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}
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static void xdp_umem_clear_dev(struct xdp_umem *umem)
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{
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struct netdev_bpf bpf;
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int err;
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if (umem->zc) {
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bpf.command = XDP_SETUP_XSK_UMEM;
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bpf.xsk.umem = NULL;
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bpf.xsk.queue_id = umem->queue_id;
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rtnl_lock();
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err = umem->dev->netdev_ops->ndo_bpf(umem->dev, &bpf);
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rtnl_unlock();
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if (err)
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WARN(1, "failed to disable umem!\n");
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}
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if (umem->dev) {
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rtnl_lock();
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xdp_clear_umem_at_qid(umem->dev, umem->queue_id);
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rtnl_unlock();
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}
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if (umem->zc) {
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dev_put(umem->dev);
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umem->zc = false;
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}
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}
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static void xdp_umem_unpin_pages(struct xdp_umem *umem)
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{
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unsigned int i;
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for (i = 0; i < umem->npgs; i++) {
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struct page *page = umem->pgs[i];
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set_page_dirty_lock(page);
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put_page(page);
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}
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kfree(umem->pgs);
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umem->pgs = NULL;
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}
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static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
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{
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if (umem->user) {
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atomic_long_sub(umem->npgs, &umem->user->locked_vm);
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free_uid(umem->user);
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}
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}
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static void xdp_umem_release(struct xdp_umem *umem)
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{
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struct task_struct *task;
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struct mm_struct *mm;
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xdp_umem_clear_dev(umem);
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if (umem->fq) {
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xskq_destroy(umem->fq);
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umem->fq = NULL;
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}
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if (umem->cq) {
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xskq_destroy(umem->cq);
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umem->cq = NULL;
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}
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xsk_reuseq_destroy(umem);
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xdp_umem_unpin_pages(umem);
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task = get_pid_task(umem->pid, PIDTYPE_PID);
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put_pid(umem->pid);
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if (!task)
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goto out;
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mm = get_task_mm(task);
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put_task_struct(task);
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if (!mm)
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goto out;
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mmput(mm);
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kfree(umem->pages);
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umem->pages = NULL;
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xdp_umem_unaccount_pages(umem);
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out:
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kfree(umem);
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}
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static void xdp_umem_release_deferred(struct work_struct *work)
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{
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struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
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xdp_umem_release(umem);
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}
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void xdp_get_umem(struct xdp_umem *umem)
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{
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refcount_inc(&umem->users);
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}
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void xdp_put_umem(struct xdp_umem *umem)
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{
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if (!umem)
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return;
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if (refcount_dec_and_test(&umem->users)) {
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INIT_WORK(&umem->work, xdp_umem_release_deferred);
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schedule_work(&umem->work);
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}
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}
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static int xdp_umem_pin_pages(struct xdp_umem *umem)
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{
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unsigned int gup_flags = FOLL_WRITE;
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long npgs;
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int err;
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umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs),
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GFP_KERNEL | __GFP_NOWARN);
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if (!umem->pgs)
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return -ENOMEM;
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down_write(¤t->mm->mmap_sem);
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npgs = get_user_pages(umem->address, umem->npgs,
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gup_flags, &umem->pgs[0], NULL);
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up_write(¤t->mm->mmap_sem);
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if (npgs != umem->npgs) {
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if (npgs >= 0) {
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umem->npgs = npgs;
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err = -ENOMEM;
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goto out_pin;
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}
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err = npgs;
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goto out_pgs;
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}
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return 0;
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out_pin:
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xdp_umem_unpin_pages(umem);
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out_pgs:
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kfree(umem->pgs);
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umem->pgs = NULL;
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return err;
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}
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static int xdp_umem_account_pages(struct xdp_umem *umem)
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{
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unsigned long lock_limit, new_npgs, old_npgs;
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if (capable(CAP_IPC_LOCK))
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return 0;
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lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
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umem->user = get_uid(current_user());
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do {
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old_npgs = atomic_long_read(&umem->user->locked_vm);
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new_npgs = old_npgs + umem->npgs;
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if (new_npgs > lock_limit) {
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free_uid(umem->user);
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umem->user = NULL;
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return -ENOBUFS;
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}
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} while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
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new_npgs) != old_npgs);
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return 0;
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}
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static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
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{
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u32 chunk_size = mr->chunk_size, headroom = mr->headroom;
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unsigned int chunks, chunks_per_page;
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u64 addr = mr->addr, size = mr->len;
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int size_chk, err, i;
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if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
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/* Strictly speaking we could support this, if:
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* - huge pages, or*
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* - using an IOMMU, or
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* - making sure the memory area is consecutive
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* but for now, we simply say "computer says no".
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*/
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return -EINVAL;
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}
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if (!is_power_of_2(chunk_size))
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return -EINVAL;
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if (!PAGE_ALIGNED(addr)) {
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/* Memory area has to be page size aligned. For
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* simplicity, this might change.
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*/
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return -EINVAL;
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}
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if ((addr + size) < addr)
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return -EINVAL;
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chunks = (unsigned int)div_u64(size, chunk_size);
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if (chunks == 0)
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return -EINVAL;
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chunks_per_page = PAGE_SIZE / chunk_size;
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if (chunks < chunks_per_page || chunks % chunks_per_page)
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return -EINVAL;
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headroom = ALIGN(headroom, 64);
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size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM;
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if (size_chk < 0)
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return -EINVAL;
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umem->pid = get_task_pid(current, PIDTYPE_PID);
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umem->address = (unsigned long)addr;
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umem->chunk_mask = ~((u64)chunk_size - 1);
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umem->size = size;
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umem->headroom = headroom;
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umem->chunk_size_nohr = chunk_size - headroom;
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umem->npgs = size / PAGE_SIZE;
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umem->pgs = NULL;
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umem->user = NULL;
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INIT_LIST_HEAD(&umem->xsk_list);
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spin_lock_init(&umem->xsk_list_lock);
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refcount_set(&umem->users, 1);
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err = xdp_umem_account_pages(umem);
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if (err)
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goto out;
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err = xdp_umem_pin_pages(umem);
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if (err)
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goto out_account;
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umem->pages = kcalloc(umem->npgs, sizeof(*umem->pages), GFP_KERNEL);
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if (!umem->pages) {
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err = -ENOMEM;
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goto out_account;
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}
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for (i = 0; i < umem->npgs; i++)
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umem->pages[i].addr = page_address(umem->pgs[i]);
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return 0;
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out_account:
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xdp_umem_unaccount_pages(umem);
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out:
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put_pid(umem->pid);
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return err;
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}
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struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
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{
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struct xdp_umem *umem;
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int err;
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umem = kzalloc(sizeof(*umem), GFP_KERNEL);
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if (!umem)
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return ERR_PTR(-ENOMEM);
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err = xdp_umem_reg(umem, mr);
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if (err) {
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kfree(umem);
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return ERR_PTR(err);
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}
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return umem;
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}
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bool xdp_umem_validate_queues(struct xdp_umem *umem)
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{
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return umem->fq && umem->cq;
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}
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