2012/2/10 윤정현 <jh0506....@samsung.com>:
> I found a problem this infinite loop case.
>
> If server is deleted, then ECORE_IPC_EVENT_SERVER_DEL callback function will
> be called in client side.
> It will happen infinite loop in ecore_ipc_shutdown if ecore_ipc_shutdown
> called in this ECORE_IPC_EVENT_SERVER_DEL callback function.
>
> For example,
> server_del_handler = ecore_event_handler_add(ECORE_IPC_EVENT_SERVER_DEL,
> _server_del_cb, NULL);
> static Eina_Bool
> _server_del_cb(void *data, int type, void *event)
> {
> ecore_ipc_shutdown();
> return EINA_TRUE;
> }
This is VERY WRONG. You should never shutdown any subsystem from
your callback functions. If you must finish the application then call
ecore_main_loop_quit() and let the main() function do all the shutdowns.
>
> If server is deleted,
> 1. _ecore_ipc_event_server_del : svr->event_count++
> 2. _server_del_cb : ecore_ipc_shutdown called
> 3. ecore_ipc_shutdown : while (servers)
> ecore_ipc_server_del(eina_list_data_get(servers))
> 4. ecore_ipc_server_del : can't eina_list_remove(servers, svr) because
> event_count != 0
> 5. infinite loop
>
> I think this while code is very dangerous whether user miss or not.
> I modified EINA_LIST_FOREACH_SAFE instead of EINA_LIST_FOREACH refer to
> ecore_con.
> Please review this patch.
>
> Thanks.
>
> ------- Original Message -------
> Sender : Carsten Haitzler<ras...@rasterman.com>
> Date : 2012-02-02 18:00 (GMT+09:00)
> Title : Re: [E-devel] [Patch] ecore_ipc - remove potential risk in
> ecore_ipc_shutdown
>
> On Wed, 01 Feb 2012 03:06:01 +0000 (GMT) Jeong-Hyun Yun
> <jh0506....@samsung.com> said:
>
>> Dear All.
>>
>> I removed potential risk in ecore_ipc_shutdown.
>>
>> If servers can't eina_list removed in ecore_ipc_server_del(),
>> for example, delete_me is true or event_count == 0 or etc.,
>> then the while loop will be infinite.
>>
>> I modified EINA_LIST_FOREACH instead of while loop.
>>
>> Please review this patch.
>
> this is dangerous. very. take a look at this line in ecore_ipc_server_del():
>
> servers = eina_list_remove(servers, svr);
>
> so what happens when as you walk a list.. you remove the exact item you are
> walking... then you try use the list node ->next member.. that you just
> freed? :)
>
> this is not a fix. it's asking for segv's.
>
> you issue is this:
>
> if (svr->event_count == 0)
>
>
> ie it wont remove until events have been spooled out from the server. this
> wont
> happen until the mainloop goes and runs again, so you have a problem. what i'd
> do is have a routine before u server_del that finds all events for that server
> and deletes them. :) the problem is that there isn't a list of these per
> server. all the events point back to this server so u basically have a
> referencing issue. if a ref that wont be removed until mainlooop flushes the
> events. you want to look over there.
>
> --
> ------------- Codito, ergo sum - "I code, therefore I am" --------------
> The Rasterman (Carsten Haitzler) ras...@rasterman.com
>
> <p> </p><p> </p>
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------------------------------------------------------------------------------
Virtualization & Cloud Management Using Capacity Planning
Cloud computing makes use of virtualization - but cloud computing
also focuses on allowing computing to be delivered as a service.
http://www.accelacomm.com/jaw/sfnl/114/51521223/
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