On 04/12/2010 12:22 PM, Xiao Guangrong wrote:
Hi Avi,
Avi Kivity wrote:
hlist_for_each_entry_safe() is supposed to be be safe against removal of
the element that is pointed to by the iteration cursor.
If we destroyed the next point, hlist_for_each_entry_safe() is unsafe.
List hlist_for_each_entry_safe()'s code:
|#define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
| for (pos = (head)->first; \
| pos&& ({ n = pos->next; 1; })&& \
| ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
| pos = n)
if n is destroyed:
'pos = n, n = pos->next'
then it access n again, it's unsafe/illegal for us.
But kvm_mmu_zap_page() will only destroy sp == tpos == pos; n points at
pos->next already, so it's safe.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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