Subject: Re: [virtio-dev] Re: [PATCH v9 3/8] migration: use bitmap_mutex in migration_bitmap_clear_dirty
On 11/27/2018 03:41 PM, Peter Xu wrote:
Ok then I'm fine with it. Though you could update the comments too if you like: /* protects modification of the bitmap and migration_dirty_pages */ QemuMutex bitmap_mutex; And it's tricky that sometimes we don't take the lock when reading this variable "migration_dirty_pages". I don't see obvious issue so far, hope it's true (at least I skipped the colo ones...).
The caller reads the value just to estimate the remaining_size, and it seems fine without a lock, because whether it reads a value before the update or after the update seem not causing an issue. Best, Wei