1.1 --- a/xen/arch/x86/mm/mem_sharing.c	Thu Jan 06 14:27:33 2011 +0000
     1.2 +++ b/xen/arch/x86/mm/mem_sharing.c	Thu Jan 06 16:58:48 2011 +0000
     1.3 @@ -502,6 +502,7 @@ int mem_sharing_nominate_page(struct p2m
     1.4  
     1.5      *phandle = 0UL;
     1.6  
     1.7 +    shr_lock(); 
     1.8      mfn = gfn_to_mfn(p2m, gfn, &p2mt);
     1.9  
    1.10      /* Check if mfn is valid */
    1.11 @@ -509,29 +510,33 @@ int mem_sharing_nominate_page(struct p2m
    1.12      if (!mfn_valid(mfn))
    1.13          goto out;
    1.14  
    1.15 +    /* Return the handle if the page is already shared */
    1.16 +    page = mfn_to_page(mfn);
    1.17 +    if (p2m_is_shared(p2mt)) {
    1.18 +        *phandle = page->shr_handle;
    1.19 +        ret = 0;
    1.20 +        goto out;
    1.21 +    }
    1.22 +
    1.23      /* Check p2m type */
    1.24      if (!p2m_is_sharable(p2mt))
    1.25          goto out;
    1.26  
    1.27      /* Try to convert the mfn to the sharable type */
    1.28 -    page = mfn_to_page(mfn);
    1.29      ret = page_make_sharable(d, page, expected_refcnt); 
    1.30      if(ret) 
    1.31          goto out;
    1.32  
    1.33      /* Create the handle */
    1.34      ret = -ENOMEM;
    1.35 -    shr_lock(); 
    1.36      handle = next_handle++;  
    1.37      if((hash_entry = mem_sharing_hash_insert(handle, mfn)) == NULL)
    1.38      {
    1.39 -        shr_unlock();
    1.40          goto out;
    1.41      }
    1.42      if((gfn_info = mem_sharing_gfn_alloc()) == NULL)
    1.43      {
    1.44          mem_sharing_hash_destroy(hash_entry);
    1.45 -        shr_unlock();
    1.46          goto out;
    1.47      }
    1.48  
    1.49 @@ -545,7 +550,6 @@ int mem_sharing_nominate_page(struct p2m
    1.50          BUG_ON(page_make_private(d, page) != 0);
    1.51          mem_sharing_hash_destroy(hash_entry);
    1.52          mem_sharing_gfn_destroy(gfn_info, 0);
    1.53 -        shr_unlock();
    1.54          goto out;
    1.55      }
    1.56  
    1.57 @@ -559,11 +563,11 @@ int mem_sharing_nominate_page(struct p2m
    1.58      gfn_info->domain = d->domain_id;
    1.59      page->shr_handle = handle;
    1.60      *phandle = handle;
    1.61 -    shr_unlock();
    1.62  
    1.63      ret = 0;
    1.64  
    1.65  out:
    1.66 +    shr_unlock();
    1.67      return ret;
    1.68  }
    1.69  
    1.70 @@ -633,14 +637,21 @@ int mem_sharing_unshare_page(struct p2m_
    1.71      struct list_head *le;
    1.72      struct domain *d = p2m->domain;
    1.73  
    1.74 +    mem_sharing_audit();
    1.75 +    /* Remove the gfn_info from the list */
    1.76 +    shr_lock();
    1.77 +    
    1.78      mfn = gfn_to_mfn(p2m, gfn, &p2mt);
    1.79 +    
    1.80 +    /* Has someone already unshared it? */
    1.81 +    if (!p2m_is_shared(p2mt)) {
    1.82 +        shr_unlock();
    1.83 +        return 0;
    1.84 +    }
    1.85  
    1.86      page = mfn_to_page(mfn);
    1.87      handle = page->shr_handle;
    1.88   
    1.89 -    mem_sharing_audit();
    1.90 -    /* Remove the gfn_info from the list */
    1.91 -    shr_lock();
    1.92      hash_entry = mem_sharing_hash_lookup(handle); 
    1.93      list_for_each(le, &hash_entry->gfns)
    1.94      {
    1.95 @@ -707,7 +718,6 @@ private_page_found:
    1.96          mem_sharing_hash_delete(handle);
    1.97      else
    1.98          atomic_dec(&nr_saved_mfns);
    1.99 -    shr_unlock();
   1.100  
   1.101      if(p2m_change_type(p2m, gfn, p2m_ram_shared, p2m_ram_rw) != 
   1.102                                                  p2m_ram_shared) 
   1.103 @@ -718,6 +728,7 @@ private_page_found:
   1.104      /* Update m2p entry */
   1.105      set_gpfn_from_mfn(mfn_x(page_to_mfn(page)), gfn);
   1.106  
   1.107 +    shr_unlock();
   1.108      return 0;
   1.109  }
   1.110