File cb88d433-libxl-mig-thread.patch of Package libvirt.11695

commit cb88d4333af6c6a489a8a00f21e8373bb88be2db
Author: Jim Fehlig <jfehlig@suse.com>
Date:   Wed Nov 12 15:32:02 2014 -0700

    libxl: Receive migration data in a thread
    
    The libxl driver receives migration data within an IO callback invoked
    by the event loop, effectively disabling the event loop while migration
    occurs.
    
    This patch moves receving of the migration data to a thread.  The
    incoming connection is still accepted in the IO callback, but control
    is immediately returned to the event loop after spawning the thread.
    
    Signed-off-by: Jim Fehlig <jfehlig@suse.com>

Index: libvirt-1.2.5/src/libxl/libxl_migration.c
===================================================================
--- libvirt-1.2.5.orig/src/libxl/libxl_migration.c
+++ libvirt-1.2.5/src/libxl/libxl_migration.c
@@ -35,6 +35,7 @@
 #include "vircommand.h"
 #include "virstring.h"
 #include "virobject.h"
+#include "virthread.h"
 #include "rpc/virnetsocket.h"
 #include "libxl_domain.h"
 #include "libxl_driver.h"
@@ -48,6 +49,7 @@ VIR_LOG_INIT("libxl.libxl_migration");
 typedef struct _libxlMigrationDstArgs {
     virObject parent;
 
+    int recvfd;
     virConnectPtr conn;
     virDomainObjPtr vm;
     unsigned int flags;
@@ -82,40 +84,78 @@ libxlMigrationDstArgsOnceInit(void)
 VIR_ONCE_GLOBAL_INIT(libxlMigrationDstArgs)
 
 static void
-libxlDoMigrateReceive(virNetSocketPtr sock,
-                      int events ATTRIBUTE_UNUSED,
-                      void *opaque)
+libxlDoMigrateReceive(void *opaque)
 {
     libxlMigrationDstArgs *args = opaque;
-    virConnectPtr conn = args->conn;
     virDomainObjPtr vm = args->vm;
     virNetSocketPtr *socks = args->socks;
     size_t nsocks = args->nsocks;
     bool paused = args->flags & VIR_MIGRATE_PAUSED;
-    libxlDriverPrivatePtr driver = conn->privateData;
+    libxlDriverPrivatePtr driver = args->conn->privateData;
+    int recvfd = args->recvfd;
+    size_t i;
+    int ret;
+
+    virObjectLock(vm);
+    ret = libxlDomainStart(driver, vm, paused, recvfd);
+    virObjectUnlock(vm);
+
+    if (ret < 0 && !vm->persistent)
+        virDomainObjListRemove(driver->domains, vm);
+
+    /* Remove all listen socks from event handler, and close them. */
+    for (i = 0; i < nsocks; i++) {
+        virNetSocketUpdateIOCallback(socks[i], 0);
+        virNetSocketRemoveIOCallback(socks[i]);
+        virNetSocketClose(socks[i]);
+        virObjectUnref(socks[i]);
+        socks[i] = NULL;
+    }
+    args->nsocks = 0;
+    VIR_FORCE_CLOSE(recvfd);
+}
+
+
+static void
+libxlMigrateReceive(virNetSocketPtr sock,
+                    int events ATTRIBUTE_UNUSED,
+                    void *opaque)
+{
+    libxlMigrationDstArgs *args = opaque;
+    virNetSocketPtr *socks = args->socks;
+    size_t nsocks = args->nsocks;
     virNetSocketPtr client_sock;
     int recvfd = -1;
+    virThread thread;
     size_t i;
-    int ret;
 
+    /* Accept migration connection */
     virNetSocketAccept(sock, &client_sock);
     if (client_sock == NULL) {
-        virReportError(VIR_ERR_OPERATION_INVALID, "%s",
-                       _("Fail to accept migration connection"));
-        goto cleanup;
+        virReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                       _("Failed to accept migration connection"));
+        goto fail;
     }
-    VIR_DEBUG("Accepted migration connection\n");
+    VIR_DEBUG("Accepted migration connection."
+              "  Spawing thread to process migration data");
     recvfd = virNetSocketDupFD(client_sock, true);
     virObjectUnref(client_sock);
 
-    virObjectLock(vm);
-    ret = libxlDomainStart(driver, vm, paused, recvfd);
-    virObjectUnlock(vm);
+    /*
+     * Avoid blocking the event loop.  Start a thread to receive
+     * the migration data
+     */
+    args->recvfd = recvfd;
+    if (virThreadCreate(&thread, false,
+                        libxlDoMigrateReceive, args) < 0) {
+        virReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                       _("Failed to create thread for receiving migration data"));
+        goto fail;
+    }
 
-    if (ret < 0 && !vm->persistent)
-        virDomainObjListRemove(driver->domains, vm);
+    return;
 
- cleanup:
+ fail:
     /* Remove all listen socks from event handler, and close them. */
     for (i = 0; i < nsocks; i++) {
         virNetSocketUpdateIOCallback(socks[i], 0);
@@ -377,7 +417,7 @@ libxlDomainMigrationPrepare(virConnectPt
 
         if (virNetSocketAddIOCallback(socks[i],
                                       VIR_EVENT_HANDLE_READABLE,
-                                      libxlDoMigrateReceive,
+                                      libxlMigrateReceive,
                                       args,
                                       virObjectFreeCallback) < 0)
             continue;