Re: [Qemu-devel] [PATCH 06/21] vl: add a tmp pointer so that a handler can delete the entry to which it belongs.

Anthony Liguori
2010-12-08T14:22:23Z

On 12/08/2010 02:11 AM, Yoshiaki Tamura wrote:
> 2010/12/8 Isaku Yamahata<yamahata@valinux.co.jp>:
>
>> QLIST_FOREACH_SAFE?
>>
> Thanks! So, it should be,
>
> QLIST_FOREACH_SAFE(e,&vm_change_state_head, entries, ne) {
> e->cb(e->opaque, running, reason);
> }
>
> I'll put it in the next spin.
>

This is still brittle though because it only allows the current handler
to delete itself. A better approach is to borrow the technique we use
with file descriptors (using a deleted flag) as that is robust against
deletion of any elements in a handler.

Regards,

Anthony Liguori

> Yoshi
>
>
>> On Thu, Nov 25, 2010 at 03:06:45PM +0900, Yoshiaki Tamura wrote:
>>
>>> By copying the next entry to a tmp pointer,
>>> qemu_del_vm_change_state_handler() can be called in the handler.
>>>
>>> Signed-off-by: Yoshiaki Tamura<tamura.yoshiaki@lab.ntt.co.jp>
>>> ---
>>> vl.c | 5 +++--
>>> 1 files changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/vl.c b/vl.c
>>> index 805e11f..6b6aec0 100644
>>> --- a/vl.c
>>> +++ b/vl.c
>>> @@ -1073,11 +1073,12 @@ void qemu_del_vm_change_state_handler(VMChangeStateEntry *e)
>>>
>>> void vm_state_notify(int running, int reason)
>>> {
>>> - VMChangeStateEntry *e;
>>> + VMChangeStateEntry *e, *ne;
>>>
>>> trace_vm_state_notify(running, reason);
>>>
>>> - for (e = vm_change_state_head.lh_first; e; e = e->entries.le_next) {
>>> + for (e = vm_change_state_head.lh_first; e; e = ne) {
>>> + ne = e->entries.le_next;
>>> e->cb(e->opaque, running, reason);
>>> }
>>> }
>>> --
>>> 1.7.1.2
>>>
>>>
>>>
>> --
>> yamahata
>> --
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