from commit 2ff6403, we make a mistake to call synchronize_rcu()
within rcu_read_lock()/rcu_read_unlock()
Signed-off-by: Li Zhijian <lizhij...@cn.fujitsu.com>
Signed-off-by: Wen Congyang <we...@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhij...@cn.fujitsu.com>
---
migration/ram.c | 49 ++++++++++++++++++++++++++++++++-----------------
1 file changed, 32 insertions(+), 17 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index c696814..51635e9 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -221,7 +221,11 @@ static RAMBlock *last_seen_block;
/* This is the last block from where we have sent data */
static RAMBlock *last_sent_block;
static ram_addr_t last_offset;
-static unsigned long *migration_bitmap;
+struct rcu_bitmap {
+ struct rcu_head rcu;
+ unsigned long *bitmap;
+};
+static struct rcu_bitmap *migration_bitmap;
static QemuMutex migration_bitmap_mutex;
static uint64_t migration_dirty_pages;
static uint32_t last_version;
@@ -504,7 +508,7 @@ ram_addr_t
migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,
unsigned long nr = base + (start >> TARGET_PAGE_BITS);
uint64_t mr_size = TARGET_PAGE_ALIGN(memory_region_size(mr));
unsigned long size = base + (mr_size >> TARGET_PAGE_BITS);
- unsigned long *bitmap;
+ struct rcu_bitmap *bitmap;
unsigned long next;
@@ -512,11 +516,11 @@ ram_addr_t
migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,
if (ram_bulk_stage && nr > base) {
next = nr + 1;
} else {
- next = find_next_bit(bitmap, size, nr);
+ next = find_next_bit(bitmap->bitmap, size, nr);
}
if (next < size) {
- clear_bit(next, bitmap);
+ clear_bit(next, bitmap->bitmap);
migration_dirty_pages--;
}
return (next - base) << TARGET_PAGE_BITS;
@@ -525,10 +529,10 @@ ram_addr_t
migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,
/* Called with rcu_read_lock() to protect migration_bitmap */
static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length)
{
- unsigned long *bitmap;
+ struct rcu_bitmap *bitmap;
bitmap = atomic_rcu_read(&migration_bitmap);
migration_dirty_pages +=
- cpu_physical_memory_sync_dirty_bitmap(bitmap, start, length);
+ cpu_physical_memory_sync_dirty_bitmap(bitmap->bitmap, start, length);
}
@@ -1024,17 +1028,29 @@ void free_xbzrle_decoded_buf(void)
xbzrle_decoded_buf = NULL;
}
+static struct rcu_bitmap *rcu_bitmap_new(long bits)
+{
+ struct rcu_bitmap *bitmap = g_malloc0(sizeof(*bitmap));
+ bitmap->bitmap = bitmap_new(bits);
+ return bitmap;
+}
+
+static void rcu_bitmap_destroy(struct rcu_bitmap *bitmap)
+{
+ g_free(bitmap->bitmap);
+ g_free(bitmap);
+}
+
static void migration_end(void)
{
/* caller have hold iothread lock or is in a bh, so there is
* no writing race against this migration_bitmap
*/
- unsigned long *bitmap = migration_bitmap;
+ struct rcu_bitmap *bitmap = migration_bitmap;
atomic_rcu_set(&migration_bitmap, NULL);
if (bitmap) {
memory_global_dirty_log_stop();
- synchronize_rcu();
- g_free(bitmap);
+ call_rcu(bitmap, rcu_bitmap_destroy, rcu);
}
XBZRLE_cache_lock();
@@ -1071,8 +1087,8 @@ void migration_bitmap_extend(ram_addr_t old, ram_addr_t
new)
* no writing race against this migration_bitmap
*/
if (migration_bitmap) {
- unsigned long *old_bitmap = migration_bitmap, *bitmap;
- bitmap = bitmap_new(new);
+ struct rcu_bitmap *old_bitmap = migration_bitmap, *bitmap;
+ bitmap = rcu_bitmap_new(new);
/* prevent migration_bitmap content from being set bit
* by migration_bitmap_sync_range() at the same time.
@@ -1080,13 +1096,12 @@ void migration_bitmap_extend(ram_addr_t old, ram_addr_t
new)
* at the same time.
*/
qemu_mutex_lock(&migration_bitmap_mutex);
- bitmap_copy(bitmap, old_bitmap, old);
- bitmap_set(bitmap, old, new - old);
+ bitmap_copy(bitmap->bitmap, old_bitmap->bitmap, old);
+ bitmap_set(bitmap->bitmap, old, new - old);
atomic_rcu_set(&migration_bitmap, bitmap);
qemu_mutex_unlock(&migration_bitmap_mutex);
migration_dirty_pages += new - old;
- synchronize_rcu();
- g_free(old_bitmap);
+ call_rcu(old_bitmap, rcu_bitmap_destroy, rcu);
}
}
@@ -1145,8 +1160,8 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
reset_ram_globals();
ram_bitmap_pages = last_ram_offset() >> TARGET_PAGE_BITS;
- migration_bitmap = bitmap_new(ram_bitmap_pages);
- bitmap_set(migration_bitmap, 0, ram_bitmap_pages);
+ migration_bitmap = rcu_bitmap_new(ram_bitmap_pages);
+ bitmap_set(migration_bitmap->bitmap, 0, ram_bitmap_pages);
/*
* Count the total number of pages used by ram blocks not including any
--
2.1.4
