migration: reuse mis->userfault_quit_fd

It was only used for quitting the page fault thread before. Let it be
something more useful - now we can use it to notify a "wake" for the
page fault thread (for any reason), and it only means "quit" if the
fault_thread_quit is set.

Since we changed what it does, renaming it to userfault_event_fd.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180208103132.28452-3-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/migration/migration.h b/migration/migration.h
index 848f638a20..75c72d3c8f 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -35,6 +35,8 @@ struct MigrationIncomingState {
     bool           have_fault_thread;
     QemuThread     fault_thread;
     QemuSemaphore  fault_thread_sem;
+    /* Set this when we want the fault thread to quit */
+    bool           fault_thread_quit;
 
     bool           have_listen_thread;
     QemuThread     listen_thread;
@@ -42,8 +44,8 @@ struct MigrationIncomingState {
 
     /* For the kernel to send us notifications */
     int       userfault_fd;
-    /* To tell the fault_thread to quit */
-    int       userfault_quit_fd;
+    /* To notify the fault_thread to wake, e.g., when need to quit */
+    int       userfault_event_fd;
     QEMUFile *to_src_file;
     QemuMutex rp_mutex;    /* We send replies from multiple threads */
     void     *postcopy_tmp_page;