diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2014-06-05 14:53:59 +0200 |
---|---|---|
committer | Stefan Hajnoczi <stefanha@redhat.com> | 2014-06-23 16:36:13 +0800 |
commit | 2bd3bce8efebe86b031beab5c0e3b9bbaec0b502 (patch) | |
tree | f0c9c33850b6e351afe75d315611bd2047cf6011 /stubs/vm-stop.c | |
parent | 74892d2468b9f0c56b915ce94848d6f7fac39740 (diff) |
block: asynchronously stop the VM on I/O errors
With virtio-blk dataplane, I/O errors might occur while QEMU is
not in the main I/O thread. However, it's invalid to call vm_stop
when we're neither in a VCPU thread nor in the main I/O thread,
even if we were to take the iothread mutex around it.
To avoid this problem, we can raise a request to the main I/O thread,
similar to what QEMU does when vm_stop is called from a CPU thread.
We know that bdrv_error_action is called from an AIO callback, and
the moment at which the callback will fire is not well-defined; it
depends on the moment at which the disk or OS finishes the operation,
which can happen at any time. Note that QEMU is certainly not in a CPU
thread and we do not need to call cpu_stop_current() like vm_stop() does.
However, we need to ensure that any action taken by management will
result in correct detection of the error _and_ a running VM. In particular:
- the event must be raised after the iostatus has been set, so that
"info block" will return an iostatus that matches the event.
- the VM must be stopped after the iostatus has been set, so that
"info block" will return an iostatus that matches the runstate.
The ordering between the STOP and BLOCK_IO_ERROR events is preserved;
BLOCK_IO_ERROR is documented to come first.
This makes bdrv_error_action() thread safe (assuming QMP events are,
which is attacked by a separate series).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'stubs/vm-stop.c')
-rw-r--r-- | stubs/vm-stop.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/stubs/vm-stop.c b/stubs/vm-stop.c index f82c897dfe..69fd86b2e8 100644 --- a/stubs/vm-stop.c +++ b/stubs/vm-stop.c @@ -1,7 +1,12 @@ #include "qemu-common.h" #include "sysemu/sysemu.h" -int vm_stop(RunState state) +void qemu_system_vmstop_request_prepare(void) +{ + abort(); +} + +void qemu_system_vmstop_request(RunState state) { abort(); } |