The main change since v3: as suggested by Stefano, the worker teardown
race is now fixed where it actually lives, i.e. in vhost_workers_free(),
instead of being guarded from the vsock side. The new patch 4 makes the
teardown wait out the RCU readers which might still be queueing work on
a worker, and then run whatever they queued, before the workers are
freed.
With the teardown itself made safe, queueing work on a stopped device
is harmless again: the work handlers check the backend under vq->mutex
and simply return. So the backend guards in send_pkt()/cancel_pkt()
and the synchronize_rcu() in reset_owner() from v3 are no longer needed
and are gone.
v3 -> v4:
* Patch 2:
- rename 'started' -> 'ever_started';
- reword commit message;
* Patch 3: reword commit message and code comment;
* Patch 4 (NEW) ("vhost: synchronize with RCU readers when freeing workers"):
- fix the vq->worker UAF and the stuck VHOST_WORK_QUEUED bit
generically in vhost_workers_free();
* Patch 4 -> 5 ("vhost/vsock: add VHOST_RESET_OWNER ioctl"):
- drop the backend guards in send_pkt()/cancel_pkt() and the
synchronize_rcu() in reset_owner() - covered by patch 4 now;
- make vhost_vsock_reset_owner() return long;
- reword commit message.
v3:
https://lore.kernel.org/virtualization/[email protected]
Andrey Drobyshev (3):
vhost/vsock: suppress EHOSTUNREACH fast-fail during CPR pause
vhost/vsock: re-scan TX virtqueue on device start
vhost: synchronize with RCU readers when freeing workers
Pavel Tikhomirov (2):
vhost/vsock: split out vhost_vsock_drop_backends helper
vhost/vsock: add VHOST_RESET_OWNER ioctl
drivers/vhost/vhost.c | 15 ++++++++++
drivers/vhost/vsock.c | 80 +++++++++++++++++++++++++++++++++++++++------------
2 files changed, 76 insertions(+), 19 deletions(-)
--
2.47.1
