[Qemu-commits] [qemu/qemu] ebb6ff: virtio-blk: Cancel the pending BH when the datapla...

[Peter Maydell]

  Branch: refs/heads/master
  Home:   https://github.com/qemu/qemu
  Commit: ebb6ff25cd888a52a64a9adc3692541c6d1d9a42
      
https://github.com/qemu/qemu/commit/ebb6ff25cd888a52a64a9adc3692541c6d1d9a42
  Author: Philippe Mathieu-Daudé <address@hidden>
  Date:   2019-09-03 (Tue, 03 Sep 2019)

  Changed paths:
    M hw/block/dataplane/virtio-blk.c

  Log Message:
  -----------
  virtio-blk: Cancel the pending BH when the dataplane is reset

When 'system_reset' is called, the main loop clear the memory
region cache before the BH has a chance to execute. Later when
the deferred function is called, some assumptions that were
made when scheduling them are no longer true when they actually
execute.

This is what happens using a virtio-blk device (fresh RHEL7.8 install):

 $ (sleep 12.3; echo system_reset; sleep 12.3; echo system_reset; sleep 1; echo 
q) \
   | qemu-system-x86_64 -m 4G -smp 8 -boot menu=on \
     -device virtio-blk-pci,id=image1,drive=drive_image1 \
     -drive 
file=/var/lib/libvirt/images/rhel78.qcow2,if=none,id=drive_image1,format=qcow2,cache=none
 \
     -device virtio-net-pci,netdev=net0,id=nic0,mac=52:54:00:c4:e7:84 \
     -netdev tap,id=net0,script=/bin/true,downscript=/bin/true,vhost=on \
     -monitor stdio -serial null -nographic
  (qemu) system_reset
  (qemu) system_reset
  (qemu) qemu-system-x86_64: hw/virtio/virtio.c:225: vring_get_region_caches: 
Assertion `caches != NULL' failed.
  Aborted

  (gdb) bt
  Thread 1 (Thread 0x7f109c17b680 (LWP 10939)):
  #0  0x00005604083296d1 in vring_get_region_caches (vq=0x56040a24bdd0) at 
hw/virtio/virtio.c:227
  #1  0x000056040832972b in vring_avail_flags (vq=0x56040a24bdd0) at 
hw/virtio/virtio.c:235
  #2  0x000056040832d13d in virtio_should_notify (vdev=0x56040a240630, 
vq=0x56040a24bdd0) at hw/virtio/virtio.c:1648
  #3  0x000056040832d1f8 in virtio_notify_irqfd (vdev=0x56040a240630, 
vq=0x56040a24bdd0) at hw/virtio/virtio.c:1662
  #4  0x00005604082d213d in notify_guest_bh (opaque=0x56040a243ec0) at 
hw/block/dataplane/virtio-blk.c:75
  #5  0x000056040883dc35 in aio_bh_call (bh=0x56040a243f10) at util/async.c:90
  #6  0x000056040883dccd in aio_bh_poll (ctx=0x560409161980) at util/async.c:118
  #7  0x0000560408842af7 in aio_dispatch (ctx=0x560409161980) at 
util/aio-posix.c:460
  #8  0x000056040883e068 in aio_ctx_dispatch (source=0x560409161980, 
callback=0x0, user_data=0x0) at util/async.c:261
  #9  0x00007f10a8fca06d in g_main_context_dispatch () at 
/lib64/libglib-2.0.so.0
  #10 0x0000560408841445 in glib_pollfds_poll () at util/main-loop.c:215
  #11 0x00005604088414bf in os_host_main_loop_wait (timeout=0) at 
util/main-loop.c:238
  #12 0x00005604088415c4 in main_loop_wait (nonblocking=0) at 
util/main-loop.c:514
  #13 0x0000560408416b1e in main_loop () at vl.c:1923
  #14 0x000056040841e0e8 in main (argc=20, argv=0x7ffc2c3f9c58, 
envp=0x7ffc2c3f9d00) at vl.c:4578

Fix this by cancelling the BH when the virtio dataplane is stopped.

[This is version of the patch was modified as discussed with Philippe on
the mailing list thread.
--Stefan]

Reported-by: Yihuang Yu <address@hidden>
Suggested-by: Stefan Hajnoczi <address@hidden>
Fixes: https://bugs.launchpad.net/qemu/+bug/1839428
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>


  Commit: cc9c8b82669e22bf2440ccb54a7a0ebee7627a28
      
https://github.com/qemu/qemu/commit/cc9c8b82669e22bf2440ccb54a7a0ebee7627a28
  Author: Peter Maydell <address@hidden>
  Date:   2019-09-13 (Fri, 13 Sep 2019)

  Changed paths:
    M hw/block/dataplane/virtio-blk.c

  Log Message:
  -----------
  Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into 
staging

Pull request

# gpg: Signature made Wed 11 Sep 2019 15:36:02 BST
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <address@hidden>" [full]
# gpg:                 aka "Stefan Hajnoczi <address@hidden>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  virtio-blk: Cancel the pending BH when the dataplane is reset

Signed-off-by: Peter Maydell <address@hidden>


Compare: https://github.com/qemu/qemu/compare/7ff91278623f...cc9c8b82669e