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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: Wei 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: Peter Xu <peterx@redhat.com>
Message-Id: <1544516693-5395-4-git-send-email-wei.w.wang@intel.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Wei Wang 2018-12-11 16:24:49 +08:00 committed by Dr. David Alan Gilbert
parent 94960256ae
commit 386a907b37
1 changed files with 4 additions and 1 deletions
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5
migration/ram.c
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@ -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;
}