[Qemu-devel] [PATCH 0/2] ide/atapi: partially avoid deadlock if the storage backend is dead

[Peter Lieven <pl@kamp.de>]

the blk_drain_all() that is executed if the guest issues a DMA cancel
leads to a stuck main loop if the storage backend (e.g. a NFS share)
is unresponsive.

This scenario is a common case for CDROM images mounted from an
NFS share. In this case a broken NFS server can take down the
whole VM even if the mounted CDROM is not used and was just not
unmounted after usage.

This approach avoids the blk_drain_all for read-only media and
cancelles the AIO locally and makes the callback a NOP if the
original request is completed after the NFS share is responsive
again.

Peter Lieven (2):
  block/io: allow AIOCB without callback
  ide/atapi: partially avoid deadlock if the storage backend is dead

 block/io.c   |  8 ++++++--
 hw/ide/pci.c | 32 ++++++++++++++++++--------------
 2 files changed, 24 insertions(+), 16 deletions(-)

-- 
1.9.1