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xdp: fix hang while unregistering device bound to xdp socket

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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: 965a990984 ("xsk: add support for bind for Rx")
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Ilya Maximets
2019-06-28 11:04:07 +03:00
committed by Daniel Borkmann
parent 162c820ed8
commit 455302d1c9
4 changed files with 87 additions and 16 deletions
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5
include/net/xdp_sock.h
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@@ -61,6 +61,11 @@ struct xdp_sock {
struct xsk_queue *tx ____cacheline_aligned_in_smp;
struct list_head list;
bool zc;
enum {
XSK_READY = 0,
XSK_BOUND,
XSK_UNBOUND,
} state;
/* Protects multiple processes in the control path */
struct mutex mutex;
/* Mutual exclusion of NAPI TX thread and sendmsg error paths