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From: | Wei Wang |
Subject: | Re: [Qemu-devel] [virtio-dev] Re: [PATCH v9 3/8] migration: use bitmap_mutex in migration_bitmap_clear_dirty |
Date: | Tue, 27 Nov 2018 18:17:13 +0800 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
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
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