[ltt-dev] [PATCH v3 0/4] Separate ltt_trace_create() into ltt_trace_create() and ltt_trace_alloc()

[Zhaolei]

Hello, I modified patchset of "Separate ltt_trace_create() into
ltt_trace_create() and ltt_trace_alloc()" based on your advice.

>> -static struct dentry *ltt_root_dentry;
>> +struct dentry *ltt_root_dentry;
>> +EXPORT_SYMBOL_GPL(ltt_root_dentry);
>> +
> 
> Hrm, I think it will cause a double declaration of ltt_root_dentry if
> both ltt-relay and ltt-relay-locked are loaded. ltt_root_dentry should
> probably sit in ltt-core.c.
ltt_root_dentry is moved into ltt-core.c.
But I think it is ltt-core.c's duty to create ltt-root in debugfs(not ltt-relay)
ltt-relay and ltt-relay-locked's dir should be in ltt-root, so dir should be:
debugfs/
`-- ltt
    |-- control
    |   `-- ...
    |-- relay
    |   `-- ...
    `-- relay-locked
        `-- ...
Maybe it will also affect user-mode tools, I'd like to impl it after new
ltt-trace-control get merged.

>> + unsigned int def_subbufsize;
>> + unsigned int def_subbufcount;
>> +} chan_infos[] = {
> 
> A declaration like this seems to work :
> 
> 
> int blah[] = {
>        [0] = 1,
>        [1] = 2,
>        [5] = 3,
>        [4] = 4,
> };
> 
> So I think you can populate the array by using :
> 
> struct chan_info_struct {
> const char *name;
> unsigned int channel_index;
> unsigned int def_subbufsize;
> unsigned int def_subbufcount;
> } chan_infos[] = {
>  [GET_CHANNEL_INDEX(cpu)] = {
>    LTT_CPU_CHANNEL,
>    LTT_DEFAULT_SUBBUF_SIZE_HIGH,
>    LTT_DEFAULT_N_SUBBUFS_HIGH,
>  },
>  .........
> };
> 
> So you don't have to force the correct declaration order.
Thanks, I changed source.
But I think "[LTT_CHANNEL_CPU] = {" is better, because using
GET_CHANNEL_INDEX() as array's index will leave a lot of blank items as:
[0] = [BLANK]
[1] = [BLANK]
[2] = [BLANK]
[3] = [BLANK]
[4] = [BLANK]
[5] = [BLANK]
[6] = [BLANK]
[7] = [BLANK]
[8] = [BLANK]
[9] = [BLANK]
[10] = [BLANK]
[11] = [BLANK]
[12] = [BLANK]
[13] = [BLANK]
[14] = [BLANK]
[15] = [BLANK]
[16] = [CPU's item]
[17] = [BLANK]
[18] = [BLANK]
[19] = [BLANK]
[20] = [PROCESSES's item]
[21] = [BLANK]
[22] = [BLANK]
[23] = [BLANK]
...
And make search and iter operation complex.

Per-channel's overwrite control function is added.
I'll post new ltt-trace-control in next mail.

After we merge this patch, we need to do following work:
1: Change user-mode tools to support debugfs-based control interface.
   (now we support both control interface)
2: Remove old netlink-based code from source.

Thanks!