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, simply 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.
This makes bdrv_error_action() thread safe.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
block.c | 2 +-
stubs/vm-stop.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/block.c b/block.c
index fc2edd3..fa41598 100644
--- a/block.c
+++ b/block.c
@@ -3515,7 +3515,7 @@ void bdrv_error_action(BlockDriverState *bs,
BlockErrorAction action,
assert(error >= 0);
bdrv_emit_qmp_error_event(bs, QEVENT_BLOCK_IO_ERROR, action, is_read);
if (action == BDRV_ACTION_STOP) {
- vm_stop(RUN_STATE_IO_ERROR);
+ qemu_system_vmstop_request(RUN_STATE_IO_ERROR);
bdrv_iostatus_set_err(bs, error);
}
}
diff --git a/stubs/vm-stop.c b/stubs/vm-stop.c
index f82c897..7fbeefd 100644
--- a/stubs/vm-stop.c
+++ b/stubs/vm-stop.c
@@ -1,7 +1,7 @@
#include "qemu-common.h"
#include "sysemu/sysemu.h"
-int vm_stop(RunState state)
+void qemu_system_vmstop_request(RunState state)
{
abort();
}
--
1.8.3.1
