From: Wei Wang <[email protected]> The bitmap mutex is used to synchronize threads to update the dirty bitmap and the migration_dirty_pages counter. For example, the free page optimization clears bits of free pages from the bitmap in an iothread context. This patch makes migration_bitmap_clear_dirty update the bitmap and counter under the mutex.
Signed-off-by: Wei Wang <[email protected]> CC: Dr. David Alan Gilbert <[email protected]> CC: Juan Quintela <[email protected]> CC: Michael S. Tsirkin <[email protected]> CC: Peter Xu <[email protected]> Reviewed-by: Peter Xu <[email protected]> Message-Id: <[email protected]> Signed-off-by: Dr. David Alan Gilbert <[email protected]> --- migration/ram.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/migration/ram.c b/migration/ram.c index 01315edd66..0747873ca9 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -342,7 +342,7 @@ struct RAMState { uint64_t target_page_count; /* number of dirty bits in the bitmap */ uint64_t migration_dirty_pages; - /* protects modification of the bitmap */ + /* Protects modification of the bitmap and migration dirty pages */ QemuMutex bitmap_mutex; /* The RAMBlock used in the last src_page_requests */ RAMBlock *last_req_rb; @@ -1590,11 +1590,14 @@ static inline bool migration_bitmap_clear_dirty(RAMState *rs, { bool ret; + qemu_mutex_lock(&rs->bitmap_mutex); ret = test_and_clear_bit(page, rb->bmap); if (ret) { rs->migration_dirty_pages--; } + qemu_mutex_unlock(&rs->bitmap_mutex); + return ret; } -- 2.20.1
