From 7b47ae208675e0da813f9f46838d9a8935c68a02 Mon Sep 17 00:00:00 2001

From: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>

Date: Thu, 8 May 2014 10:58:41 +0200

Subject: [PATCH 06/31] Init the XBZRLE.lock in ram_mig_init

RH-Author: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>

Message-id: <1399546722-6350-4-git-send-email-dgilbert@redhat.com>

Patchwork-id: 58743

O-Subject: [RHEL7.1/RHEL7.0.z qemu-kvm PATCH 3/4] Init the XBZRLE.lock in ram_mig_init

Bugzilla: 1066338

RH-Acked-by: Juan Quintela <quintela@redhat.com>

RH-Acked-by: Markus Armbruster <armbru@redhat.com>

RH-Acked-by: Amit Shah <amit.shah@redhat.com>

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Initialising the XBZRLE.lock earlier simplifies the lock use.

Based on Markus's patch in:

http://lists.gnu.org/archive/html/qemu-devel/2014-03/msg03879.html

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Gonglei <arei.gonglei@huawei.com>

Reviewed-by: Markus Armbruster <armbru@redhat.com>

Signed-off-by: Juan Quintela <quintela@redhat.com>

(cherry picked from commit d97326eec2ca1313eaf0b5cffd69af5663b5af5d)

---

 arch_init.c | 61 +++++++++++++++++++++++++++++++------------------------------

 1 file changed, 31 insertions(+), 30 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 arch_init.c |   61 ++++++++++++++++++++++++++++++-----------------------------

 1 files changed, 31 insertions(+), 30 deletions(-)

diff --git a/arch_init.c b/arch_init.c

index 37c9f6d..80e48f2 100644

--- a/arch_init.c

+++ b/arch_init.c

@@ -45,6 +45,7 @@

 #include "hw/audio/pcspk.h"

 #include "migration/page_cache.h"

 #include "qemu/config-file.h"

+#include "qemu/error-report.h"

 #include "qmp-commands.h"

 #include "trace.h"

 #include "exec/cpu-all.h"

@@ -167,11 +168,8 @@ static struct {

     /* Cache for XBZRLE, Protected by lock. */

     PageCache *cache;

     QemuMutex lock;

-} XBZRLE = {

-    .encoded_buf = NULL,

-    .current_buf = NULL,

-    .cache = NULL,

-};

+} XBZRLE;

+

 /* buffer used for XBZRLE decoding */

 static uint8_t *xbzrle_decoded_buf;

@@ -187,41 +185,44 @@ static void XBZRLE_cache_unlock(void)

         qemu_mutex_unlock(&XBZRLE.lock);

 }

+/*

+ * called from qmp_migrate_set_cache_size in main thread, possibly while

+ * a migration is in progress.

+ * A running migration maybe using the cache and might finish during this

+ * call, hence changes to the cache are protected by XBZRLE.lock().

+ */

 int64_t xbzrle_cache_resize(int64_t new_size)

 {

-    PageCache *new_cache, *cache_to_free;

+    PageCache *new_cache;

+    int64_t ret;

     if (new_size < TARGET_PAGE_SIZE) {

         return -1;

     }

-    /* no need to lock, the current thread holds qemu big lock */

+    XBZRLE_cache_lock();

+

     if (XBZRLE.cache != NULL) {

-        /* check XBZRLE.cache again later */

         if (pow2floor(new_size) == migrate_xbzrle_cache_size()) {

-            return pow2floor(new_size);

+            goto out_new_size;

         }

         new_cache = cache_init(new_size / TARGET_PAGE_SIZE,

                                         TARGET_PAGE_SIZE);

         if (!new_cache) {

-            DPRINTF("Error creating cache\n");

-            return -1;

-        }

-

-        XBZRLE_cache_lock();

-        /* the XBZRLE.cache may have be destroyed, check it again */

-        if (XBZRLE.cache != NULL) {

-            cache_to_free = XBZRLE.cache;

-            XBZRLE.cache = new_cache;

-        } else {

-            cache_to_free = new_cache;

+            error_report("Error creating cache");

+            ret = -1;

+            goto out;

         }

-        XBZRLE_cache_unlock();

-        cache_fini(cache_to_free);

+        cache_fini(XBZRLE.cache);

+        XBZRLE.cache = new_cache;

     }

-    return pow2floor(new_size);

+out_new_size:

+    ret = pow2floor(new_size);

+out:

+    XBZRLE_cache_unlock();

+    return ret;

 }

 /* accounting for migration statistics */

@@ -735,28 +736,27 @@ static int ram_save_setup(QEMUFile *f, void *opaque)

     dirty_rate_high_cnt = 0;

     if (migrate_use_xbzrle()) {

-        qemu_mutex_lock_iothread();

+        XBZRLE_cache_lock();

         XBZRLE.cache = cache_init(migrate_xbzrle_cache_size() /

                                   TARGET_PAGE_SIZE,

                                   TARGET_PAGE_SIZE);

         if (!XBZRLE.cache) {

-            qemu_mutex_unlock_iothread();

-            DPRINTF("Error creating cache\n");

+            XBZRLE_cache_unlock();

+            error_report("Error creating cache");

             return -1;

         }

-        qemu_mutex_init(&XBZRLE.lock);

-        qemu_mutex_unlock_iothread();

+        XBZRLE_cache_unlock();

         /* We prefer not to abort if there is no memory */

         XBZRLE.encoded_buf = g_try_malloc0(TARGET_PAGE_SIZE);

         if (!XBZRLE.encoded_buf) {

-            DPRINTF("Error allocating encoded_buf\n");

+            error_report("Error allocating encoded_buf");

             return -1;

         }

         XBZRLE.current_buf = g_try_malloc(TARGET_PAGE_SIZE);

         if (!XBZRLE.current_buf) {

-            DPRINTF("Error allocating current_buf\n");

+            error_report("Error allocating current_buf");

             g_free(XBZRLE.encoded_buf);

             XBZRLE.encoded_buf = NULL;

             return -1;

@@ -1110,6 +1110,7 @@ static SaveVMHandlers savevm_ram_handlers = {

 void ram_mig_init(void)

 {

+    qemu_mutex_init(&XBZRLE.lock);

     register_savevm_live(NULL, "ram", 0, 4, &savevm_ram_handlers, NULL);

 }

-- 

1.7.1