On 27 Jun 2019, at 3:15, Ilya Maximets wrote:
Device that bound to XDP socket will not have zero refcount until the
userspace application will not close it. This leads to hang inside
'netdev_wait_allrefs()' if device unregistering requested:
# ip link del p1
< hang on recvmsg on netlink socket >
# ps -x | grep ip
5126 pts/0 D+ 0:00 ip link del p1
# journalctl -b
Jun 05 07:19:16 kernel:
unregister_netdevice: waiting for p1 to become free. Usage count = 1
Jun 05 07:19:27 kernel:
unregister_netdevice: waiting for p1 to become free. Usage count = 1
...
Fix that by implementing NETDEV_UNREGISTER event notification handler
to properly clean up all the resources and unref device.
This should also allow socket killing via ss(8) utility.
Fixes: 965a99098443 ("xsk: add support for bind for Rx")
Signed-off-by: Ilya Maximets <i.maximets@xxxxxxxxxxx>
---
include/net/xdp_sock.h | 5 +++
net/xdp/xdp_umem.c | 10 ++---
net/xdp/xdp_umem.h | 1 +
net/xdp/xsk.c | 87
++++++++++++++++++++++++++++++++++++------
4 files changed, 87 insertions(+), 16 deletions(-)
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index d074b6d60f8a..82d153a637c7 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -61,6 +61,11 @@ struct xdp_sock {
struct xsk_queue *tx ____cacheline_aligned_in_smp;
struct list_head list;
bool zc;
+ enum {
+ XSK_UNINITIALIZED = 0,
+ XSK_BINDED,
+ XSK_UNBINDED,
+ } state;
I'd prefer that these were named better, perhaps:
XSK_READY,
XSK_BOUND,
XSK_UNBOUND,
Other than that:
Acked-by: Jonathan Lemon <jonathan.lemon@xxxxxxxxx>
--
Jonathan
/* Protects multiple processes in the control path */
struct mutex mutex;
/* Mutual exclusion of NAPI TX thread and sendmsg error paths
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 267b82a4cbcf..20c91f02d3d8 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -140,11 +140,13 @@ int xdp_umem_assign_dev(struct xdp_umem *umem,
struct net_device *dev,
return err;
}
-static void xdp_umem_clear_dev(struct xdp_umem *umem)
+void xdp_umem_clear_dev(struct xdp_umem *umem)
{
struct netdev_bpf bpf;
int err;
+ ASSERT_RTNL();
+
if (!umem->dev)
return;
@@ -153,17 +155,13 @@ static void xdp_umem_clear_dev(struct xdp_umem
*umem)
bpf.xsk.umem = NULL;
bpf.xsk.queue_id = umem->queue_id;
- rtnl_lock();
err = umem->dev->netdev_ops->ndo_bpf(umem->dev, &bpf);
- rtnl_unlock();
if (err)
WARN(1, "failed to disable umem!\n");
}
- rtnl_lock();
xdp_clear_umem_at_qid(umem->dev, umem->queue_id);
- rtnl_unlock();
dev_put(umem->dev);
umem->dev = NULL;
@@ -195,7 +193,9 @@ static void xdp_umem_unaccount_pages(struct
xdp_umem *umem)
static void xdp_umem_release(struct xdp_umem *umem)
{
+ rtnl_lock();
xdp_umem_clear_dev(umem);
+ rtnl_unlock();
ida_simple_remove(&umem_ida, umem->id);
diff --git a/net/xdp/xdp_umem.h b/net/xdp/xdp_umem.h
index 27603227601b..a63a9fb251f5 100644
--- a/net/xdp/xdp_umem.h
+++ b/net/xdp/xdp_umem.h
@@ -10,6 +10,7 @@
int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device
*dev,
u16 queue_id, u16 flags);
+void xdp_umem_clear_dev(struct xdp_umem *umem);
bool xdp_umem_validate_queues(struct xdp_umem *umem);
void xdp_get_umem(struct xdp_umem *umem);
void xdp_put_umem(struct xdp_umem *umem);
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index a14e8864e4fa..336723948a36 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -335,6 +335,22 @@ static int xsk_init_queue(u32 entries, struct
xsk_queue **queue,
return 0;
}
+static void xsk_unbind_dev(struct xdp_sock *xs)
+{
+ struct net_device *dev = xs->dev;
+
+ if (!dev || xs->state != XSK_BINDED)
+ return;
+
+ xs->state = XSK_UNBINDED;
+
+ /* Wait for driver to stop using the xdp socket. */
+ xdp_del_sk_umem(xs->umem, xs);
+ xs->dev = NULL;
+ synchronize_net();
+ dev_put(dev);
+}
+
static int xsk_release(struct socket *sock)
{
struct sock *sk = sock->sk;
@@ -354,15 +370,7 @@ static int xsk_release(struct socket *sock)
sock_prot_inuse_add(net, sk->sk_prot, -1);
local_bh_enable();
- if (xs->dev) {
- struct net_device *dev = xs->dev;
-
- /* Wait for driver to stop using the xdp socket. */
- xdp_del_sk_umem(xs->umem, xs);
- xs->dev = NULL;
- synchronize_net();
- dev_put(dev);
- }
+ xsk_unbind_dev(xs);
xskq_destroy(xs->rx);
xskq_destroy(xs->tx);
@@ -412,7 +420,7 @@ static int xsk_bind(struct socket *sock, struct
sockaddr *addr, int addr_len)
return -EINVAL;
mutex_lock(&xs->mutex);
- if (xs->dev) {
+ if (xs->state != XSK_UNINITIALIZED) {
err = -EBUSY;
goto out_release;
}
@@ -492,6 +500,8 @@ static int xsk_bind(struct socket *sock, struct
sockaddr *addr, int addr_len)
out_unlock:
if (err)
dev_put(dev);
+ else
+ xs->state = XSK_BINDED;
out_release:
mutex_unlock(&xs->mutex);
return err;
@@ -520,6 +530,10 @@ static int xsk_setsockopt(struct socket *sock,
int level, int optname,
return -EFAULT;
mutex_lock(&xs->mutex);
+ if (xs->state != XSK_UNINITIALIZED) {
+ mutex_unlock(&xs->mutex);
+ return -EBUSY;
+ }
q = (optname == XDP_TX_RING) ? &xs->tx : &xs->rx;
err = xsk_init_queue(entries, q, false);
mutex_unlock(&xs->mutex);
@@ -534,7 +548,7 @@ static int xsk_setsockopt(struct socket *sock, int
level, int optname,
return -EFAULT;
mutex_lock(&xs->mutex);
- if (xs->umem) {
+ if (xs->state != XSK_UNINITIALIZED || xs->umem) {
mutex_unlock(&xs->mutex);
return -EBUSY;
}
@@ -561,6 +575,10 @@ static int xsk_setsockopt(struct socket *sock,
int level, int optname,
return -EFAULT;
mutex_lock(&xs->mutex);
+ if (xs->state != XSK_UNINITIALIZED) {
+ mutex_unlock(&xs->mutex);
+ return -EBUSY;
+ }
if (!xs->umem) {
mutex_unlock(&xs->mutex);
return -EINVAL;
@@ -662,6 +680,9 @@ static int xsk_mmap(struct file *file, struct
socket *sock,
unsigned long pfn;
struct page *qpg;
+ if (xs->state != XSK_UNINITIALIZED)
+ return -EBUSY;
+
if (offset == XDP_PGOFF_RX_RING) {
q = READ_ONCE(xs->rx);
} else if (offset == XDP_PGOFF_TX_RING) {
@@ -693,6 +714,38 @@ static int xsk_mmap(struct file *file, struct
socket *sock,
size, vma->vm_page_prot);
}
+static int xsk_notifier(struct notifier_block *this,
+ unsigned long msg, void *ptr)
+{
+ struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+ struct net *net = dev_net(dev);
+ struct sock *sk;
+
+ switch (msg) {
+ case NETDEV_UNREGISTER:
+ mutex_lock(&net->xdp.lock);
+ sk_for_each(sk, &net->xdp.list) {
+ struct xdp_sock *xs = xdp_sk(sk);
+
+ mutex_lock(&xs->mutex);
+ if (xs->dev == dev) {
+ sk->sk_err = ENETDOWN;
+ if (!sock_flag(sk, SOCK_DEAD))
+ sk->sk_error_report(sk);
+
+ xsk_unbind_dev(xs);
+
+ /* Clear device references in umem. */
+ xdp_umem_clear_dev(xs->umem);
+ }
+ mutex_unlock(&xs->mutex);
+ }
+ mutex_unlock(&net->xdp.lock);
+ break;
+ }
+ return NOTIFY_DONE;
+}
+
static struct proto xsk_proto = {
.name = "XDP",
.owner = THIS_MODULE,
@@ -764,6 +817,7 @@ static int xsk_create(struct net *net, struct
socket *sock, int protocol,
sock_set_flag(sk, SOCK_RCU_FREE);
xs = xdp_sk(sk);
+ xs->state = XSK_UNINITIALIZED;
mutex_init(&xs->mutex);
spin_lock_init(&xs->tx_completion_lock);
@@ -784,6 +838,10 @@ static const struct net_proto_family
xsk_family_ops = {
.owner = THIS_MODULE,
};
+static struct notifier_block xsk_netdev_notifier = {
+ .notifier_call = xsk_notifier,
+};
+
static int __net_init xsk_net_init(struct net *net)
{
mutex_init(&net->xdp.lock);
@@ -816,8 +874,15 @@ static int __init xsk_init(void)
err = register_pernet_subsys(&xsk_net_ops);
if (err)
goto out_sk;
+
+ err = register_netdevice_notifier(&xsk_netdev_notifier);
+ if (err)
+ goto out_pernet;
+
return 0;
+out_pernet:
+ unregister_pernet_subsys(&xsk_net_ops);
out_sk:
sock_unregister(PF_XDP);
out_proto:
--
2.17.1
