From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 26 Mar 2013 14:45:16 +0000 (+0100)
Subject: qemu: Set migration FD blocking
X-Git-Tag: v0.10.2.4~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2bcf1522ff4b72e559cd5203ab916fad2e2d6b15;p=thirdparty%2Flibvirt.git

qemu: Set migration FD blocking

Since we switched from direct host migration scheme to the one,
where we connect to the destination and then just pass a FD to a
qemu, we have uncovered a qemu bug. Qemu expects migration FD to
block. However, we are passing a nonblocking one which results in
cryptic error messages like:

  qemu: warning: error while loading state section id 2
  load of migration failed

The bug is already known to Qemu folks, but we should workaround
already released Qemus. Patch has been originally proposed by Stefan
Hajnoczi <stefanha@gmail.com>
(cherry picked from commit ceb31795af40f6127a541076b905935ff83e5b11)
---

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 1da353c3a7..7decf13220 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1811,6 +1811,13 @@ qemuMigrationConnect(struct qemud_driver *driver,
         spec->dest.fd.qemu == -1)
         goto cleanup;
 
+    /* Migration expects a blocking FD */
+    if (virSetBlocking(spec->dest.fd.qemu, true) < 0) {
+        virReportSystemError(errno, _("Unable to set FD %d blocking"),
+                             spec->dest.fd.qemu);
+        goto cleanup;
+    }
+
     ret = 0;
 
 cleanup: