Commit 386a907b authored by Wei Wang's avatar Wei Wang Committed by Dr. David Alan Gilbert
Browse files

migration: use bitmap_mutex in migration_bitmap_clear_dirty 



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: default avatarWei Wang <wei.w.wang@intel.com>
CC: Dr. David Alan Gilbert <dgilbert@redhat.com>
CC: Juan Quintela <quintela@redhat.com>
CC: Michael S. Tsirkin <mst@redhat.com>
CC: Peter Xu <peterx@redhat.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <1544516693-5395-4-git-send-email-wei.w.wang@intel.com>
Signed-off-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
parent 94960256

migration/ram.c

+4 −1
Original line number Diff line number Diff line
@@ -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;

}