On Mon, 2009-06-08 at 14:28 +0300, Uri Lublin wrote:
It may happen that the io-handler is still registered. That causes
select() to return with EBADF, not calling handlers for other fds.
The io-handler would be registered when (on the source) the whole state
was written but not yet flushed. For example when using QEMUFileBuffered,
(tcp-migration) there may be data left in a buffer waiting to be transferred.
In such a case buffered_close() calls buffered_flush() which calls
migrate_fd_put_buffer, which may, upon EAGAIN, register migrate_fd_put_notify
as a handler.
Signed-off-by: Uri Lublin<address@hidden>
---
migration.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/migration.c b/migration.c
index 401383c..57f2a52 100644
--- a/migration.c
+++ b/migration.c
@@ -301,5 +301,7 @@ void migrate_fd_wait_for_unfreeze(void *opaque)
int migrate_fd_close(void *opaque)
{
FdMigrationState *s = opaque;
+
+ qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
Looks good, but perhaps a comment explaining how the I/O handler could
possibly be registered here would be useful - at first glance, it seemed
to me that the I/O handler should always be de-registered in
migrate_fd_cleanup() before getting here.
The key to understanding the problem is that qemu_fclose() on a buffered
file can cause I/O to be flushed.