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Blame SOURCES/kvm-dirty-bitmap-fix-double-lock-on-bitmap-enabling.patch

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From c2d0ba193251782ce258dff254b00848bfc3de5a Mon Sep 17 00:00:00 2001
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From: John Snow <jsnow@redhat.com>
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Date: Wed, 18 Jul 2018 22:54:43 +0200
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Subject: [PATCH 225/268] dirty-bitmap: fix double lock on bitmap enabling
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RH-Author: John Snow <jsnow@redhat.com>
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Message-id: <20180718225511.14878-8-jsnow@redhat.com>
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Patchwork-id: 81403
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O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 07/35] dirty-bitmap: fix double lock on bitmap enabling
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Bugzilla: 1207657
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RH-Acked-by: Eric Blake <eblake@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Bitmap lock/unlock were added to bdrv_enable_dirty_bitmap in
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8b1402ce80d, but some places were not updated correspondingly, which
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leads to trying to take this lock twice, which is dead-lock. Fix this.
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Actually, iotest 199 (about dirty bitmap postcopy migration) is broken
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now, and this fixes it.
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Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Message-id: 20180625165745.25259-3-vsementsov@virtuozzo.com
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Signed-off-by: John Snow <jsnow@redhat.com>
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(cherry picked from commit 58f72b965e9e1820d246329461216c4d13140122)
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Signed-off-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/dirty-bitmap.c           | 3 ++-
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 migration/block-dirty-bitmap.c | 4 ++--
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 2 files changed, 4 insertions(+), 3 deletions(-)
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diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
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index 4d6ae8b..f580c1a 100644
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--- a/block/dirty-bitmap.c
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+++ b/block/dirty-bitmap.c
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@@ -259,8 +259,9 @@ void bdrv_enable_dirty_bitmap_locked(BdrvDirtyBitmap *bitmap)
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 /* Called with BQL taken. */
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 void bdrv_dirty_bitmap_enable_successor(BdrvDirtyBitmap *bitmap)
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 {
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+    assert(bitmap->mutex == bitmap->successor->mutex);
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     qemu_mutex_lock(bitmap->mutex);
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-    bdrv_enable_dirty_bitmap(bitmap->successor);
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+    bdrv_enable_dirty_bitmap_locked(bitmap->successor);
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     qemu_mutex_unlock(bitmap->mutex);
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 }
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diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
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index dd04f10..abba0b6 100644
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--- a/migration/block-dirty-bitmap.c
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+++ b/migration/block-dirty-bitmap.c
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@@ -511,7 +511,7 @@ void dirty_bitmap_mig_before_vm_start(void)
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         DirtyBitmapLoadBitmapState *b = item->data;
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         if (b->migrated) {
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-            bdrv_enable_dirty_bitmap(b->bitmap);
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+            bdrv_enable_dirty_bitmap_locked(b->bitmap);
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         } else {
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             bdrv_dirty_bitmap_enable_successor(b->bitmap);
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         }
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@@ -547,7 +547,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
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         if (enabled_bitmaps == NULL) {
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             /* in postcopy */
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             bdrv_reclaim_dirty_bitmap_locked(s->bs, s->bitmap, &error_abort);
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-            bdrv_enable_dirty_bitmap(s->bitmap);
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+            bdrv_enable_dirty_bitmap_locked(s->bitmap);
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         } else {
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             /* target not started, successor must be empty */
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             int64_t count = bdrv_get_dirty_count(s->bitmap);
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-- 
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1.8.3.1
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