DFC-OpenSource / ox-ctrl

In the latest v2.6 version, I saw the channel counter is decremented twice in gl-prov. The first call is at [1] when gl-prov allocates the provision list. The second call is at [2] when the provision list is freed (after writes have been executed). This is clearly a bug and the channel counter should only be decremented once.

The question is when should the counter be decremented? Perhaps it should be decremented at [2] after writes have been executed.

[1]

ox-ctrl/ftl/ox-app/block/oxb-gl-prov.c

Line 233 in 1fd9aea

app_ch_dec_thread(prov_ppa->ch[ch_id]);

[2]

ox-ctrl/ftl/ox-app/block/oxb-gl-prov.c

Line 271 in 1fd9aea

app_ch_dec_thread(ppas->ch[i]);

Dear Chen,

Thank you for opening the issue. I have analyzed it this is what I found:

We have 2 arrays:
(i) prov_ppa->ch[ch_id] : Stores pointers to channels of provisioned PPAs. If a position is NULL, the related channel (with the same index) is not provisioned.
(ii) dec_ch[ch_id] : Stores pointers to channels that NOT provisioned. If a position is NULL, the related channel is provisioned.

It starts by setting ALL active channels to both arrays:

ox-ctrl/ftl/ox-app/block/oxb-gl-prov.c

Line 117 in 1fd9aea

prov_ppa->ch[ch_id] = dec_ch[ch_id] = ch[ch_id];
Provisioned channels are removed from 'dec_ch':

ox-ctrl/ftl/ox-app/block/oxb-gl-prov.c

Line 195 in 1fd9aea

dec_ch[ch_id] = NULL;

After PPAs are provisioned, we decrease channels that might have been deactivated during the process and channels that were not used (we check for NULL pointers at 'dec_ch'):

ox-ctrl/ftl/ox-app/block/oxb-gl-prov.c

Lines 231 to 233 in 1fd9aea

    
           for (ch_id = 0; ch_id < app_nch; ch_id++) { 
        
               if (dec_ch[ch_id] != NULL) 
        
                   app_ch_dec_thread(prov_ppa->ch[ch_id]);

Note: 'dec_ch' was defined because we need the pointer to the channels to be decreased at line 233.
Note: We start the function by increasing all active channels, and decrease the ones that were not provisioned at the end.

Suggestion: We may change the function to increase only provisioned channels. The increase function replaces the 'dec_ch' array at the line:

ox-ctrl/ftl/ox-app/block/oxb-gl-prov.c

Line 195 in 1fd9aea

dec_ch[ch_id] = NULL;

Any comments?

Hi Ivan,

To summarize the analysis, the non-provisioned channels can be decremented twice, one after provisioning and one after writing is completed.

To address this problem, after we decrement the non-provisioned channels, shouldn't we unset the corresponding channel from prov_ppa->ch to NULL?

	for (ch_id = 0; ch_id < app_nch; ch_id++) {
	if (dec_ch[ch_id] != NULL)
	app_ch_dec_thread(prov_ppa->ch[ch_id]);

Double calling of app_ch_dec_thread