[Freeipa-devel] [PATCH] check pending_return after dbus_connection_send_with_reply

[Stephen Gallagher]

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On 06/24/2009 08:45 AM, Stephen Gallagher wrote:
> On 06/24/2009 08:43 AM, Simo Sorce wrote:
>> On Wed, 2009-06-24 at 06:06 -0400, Stephen Gallagher wrote:
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>>> On 06/24/2009 03:37 AM, Sumit Bose wrote:
>>>> Am 23.06.2009 23:18, schrieb Simo Sorce:
>>>>> On Tue, 2009-06-23 at 15:05 +0200, Sumit Bose wrote:
>>>>>> Hi,
>>>>>>
>>>>>> according to
>>>>>> http://dbus.freedesktop.org/doc/dbus/api/html/group__DBusConnection.html#ga951b2a6f6c4069fa392752000b24ebe
>>>>>> dbus_connection_send_with_reply can return TRUE, but set pending_return
>>>>>> to NULL. This patch adds a check to protect the following call which try
>>>>>> to use pending_return.
>>>>>>
>>>>>> I have found this while running some load tests with >40 parallel
>>>>>> authentication requests.
>>>>> Your patch will cacth it but the effect is the same (we will ourselves).
>>>>> Do you know in what cases this can happen and what it means ?
>>>> According to the url above pending_return == NULL means that the
>>>> connection is disconnected.
>>>>
>>>>> Why does it return true if pending_return is null ?
>>>>>
>>> Simo, the function only returns false if there was a memory allocation
>>> error.
>>>> dbus at lists.freedesktop.org ?
>>>>
>>>>> Is there anything we can do, like loop back and retry 2-3 times before
>>>>> giving up ?
>>>>>
>>>> I do not know if it makes sense here. If the connection is disconnected
>>>> the reason might be that the other side of the connection died. If the
>>>> other side is restarted by the monitor can we use the old connection or
>>>> it is necessary to reconnect?
>>>>
>>> I agree with Sumit. The only reason a peer-to-peer D-BUS connection
>>> would be disconnected is if one end of it exited. So retrying is just
>>> wasting cycles. It's better to just kill it off and let the monitor
>>> restart the offending process.
>> I'd rather reconnect if possible.
>> Killing off a backend would entail reconnecting to remote servers or
>> perform other initialization, etc.. It would be nice if we could avoid
>> that when possible, and leave deadly measures to when we can't do
>> anything else.
> 
>> Simo.
> 
> 
> Simo, what I was saying is that if the connection has disconnected, then
> the service has already exited. (I.E. the backend has already died and
> needs to re-init anyway)
> 

Pushed to master.

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Stephen Gallagher
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