[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v3 1/2] migration: protect migration_bitmap
From: |
Li Zhijian |
Subject: |
[Qemu-devel] [PATCH v3 1/2] migration: protect migration_bitmap |
Date: |
Thu, 2 Jul 2015 20:18:05 +0800 |
Signed-off-by: Li Zhijian <address@hidden>
Signed-off-by: Wen Congyang <address@hidden>
Signed-off-by: Juan Quintela <address@hidden>
---
migration/ram.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index 57368e1..187dbbb 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -494,6 +494,7 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t
**current_data,
return 1;
}
+/* Called with rcu_read_lock() to protect migration_bitmap */
static inline
ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,
ram_addr_t start)
@@ -502,26 +503,31 @@ 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;
unsigned long next;
+ bitmap = atomic_rcu_read(&migration_bitmap);
if (ram_bulk_stage && nr > base) {
next = nr + 1;
} else {
- next = find_next_bit(migration_bitmap, size, nr);
+ next = find_next_bit(bitmap, size, nr);
}
if (next < size) {
- clear_bit(next, migration_bitmap);
+ clear_bit(next, bitmap);
migration_dirty_pages--;
}
return (next - base) << TARGET_PAGE_BITS;
}
+/* 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;
+ bitmap = atomic_rcu_read(&migration_bitmap);
migration_dirty_pages +=
- cpu_physical_memory_sync_dirty_bitmap(migration_bitmap, start, length);
+ cpu_physical_memory_sync_dirty_bitmap(bitmap, start, length);
}
@@ -1017,10 +1023,15 @@ void free_xbzrle_decoded_buf(void)
static void migration_end(void)
{
- if (migration_bitmap) {
+ /* 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;
+ atomic_rcu_set(&migration_bitmap, NULL);
+ if (bitmap) {
memory_global_dirty_log_stop();
- g_free(migration_bitmap);
- migration_bitmap = NULL;
+ synchronize_rcu();
+ g_free(bitmap);
}
XBZRLE_cache_lock();
--
2.1.4