Custom SNMP subagent

Hi all,

I have a question concerning SNMP on linux. I am making a custom SNMP
sub-agent to be able to get and set some specific information about my
systems. That is working almost fine, but ...
If I change one of the settings via an external program on the system,
I have to perform 2 snmpget's in order to be able to get the correct
value.
It seams like the first time a perform the snmpget, first the
currently stored value is returned, and after that the
processBrightnessRequest is called. (see code below)
Is there a way to make sure that the callback function is called (and
finished) prior to returning a value, or am I using the wrong
functions altogether?
If this is not the correct newsgroup for this question, please refer
me to the correct place.
Thanks a lot in advance,

Dirk

A code snippet:
void init_dZidcmBrightness(void) {
netsnmp_handler_registration *reg;
netsnmp_watcher_info *winfo;

static oid dZidcmBrightness_oid[] =
{ 1,3,6,1,4,1,1327,1,2,2,1,1,2 };

reg = netsnmp_create_handler_registration("dZidcmBrightn ess",
processBrightnessRequest, dZidcmBrightness_oid,
OID_LENGTH(dZidcmBrightness_oid), HANDLER_CAN_RWRITE);
winfo = netsnmp_create_watcher_info(&dZidcmBrightness, sizeof(long),
ASN_INTEGER, WATCHER_FIXED_SIZE);
if (netsnmp_register_watched_scalar( reg, winfo ) < 0 ) {
snmp_log( LOG_ERR, "Failed to register watched
dZidcmBrightness" );
}
}

int processBrightnessRequest(netsnmp_mib_handler *handler,
netsnmp_handler_registration *reginfo,
netsnmp_agent_request_info *reqinfo,
netsnmp_request_info *requests) {

DZ_RETURN_VALUE result = -1;

switch (reqinfo->mode) {
case MODE_GET:
// Read the value
MonitorGetBrightness(&dZidcmBrightness);
break;
case MODE_SET_RESERVE1:
break;
case MODE_SET_RESERVE2:
break;
case MODE_SET_FREE:
break;
case MODE_SET_ACTION:
// Set the value
result = MonitorSetBrightness(*(requests->requestvb-
>val.integer));
break;
case MODE_SET_COMMIT:
break;
case MODE_SET_UNDO:
break;
default:
snmp_log(LOG_INFO, "Unknown mode\n\n");
}
return 0;
}