[PATCH] ubusd: convert tx_queue to linked list

[Arnout Vandecappelle]

On 24/03/2021 08:52, Arnout Vandecappelle wrote:
> 
> 
> On 23/03/2021 17:16, Petr Štetiar wrote:
>> Arnout Vandecappelle (Essensium/Mind) <arnout at mind.be> [2021-03-23 16:23:25]:
>>
>> Hi,
>>
>>> To maintain the linked list, an additional structure ubus_msg_buf_list
>>> is created. We could also have added the linked list to the ubus_msg_buf
>>> struct itself, but it is not relevant in the many other uses of the
>>> ubus_msg_buf struct so it would just complicate things.
>>
>> I've just tried to run CI pipeline[1] on this patch and got following complaints
>> from clang static analyzer[2]:
>>
>>  ubusd_main.c:33:3: warning: Use of memory after it is freed [unix.Malloc]
>>                  ubus_msg_list_free(ubl);
>>                  ^~~~~~~~~~~~~~~~~~~~~~~
>>
>>  ubusd_main.c:76:39: warning: Use of memory after it is freed [unix.Malloc]
>>                  written = ubus_msg_writev(sock->fd, ubl->msg, ubl->offset);
>>                                                      ^~~~~~~~
>>
>> 1. https://gitlab.com/ynezz/openwrt-ubus/-/pipelines/275104805
>> 2. https://ynezz.gitlab.io/-/openwrt-ubus/-/jobs/1121145462/artifacts/build/scan/2021-03-23-154521-70-1/index.html
> 
>  This is a false positive. I suspect that clang doesn't see that !list_empty()
> implies that the list is not empty. I'll try to rewrite using assigning to ubl
> in the while loop header rather than in the body.

 Duh, that doesn't work - list_first_entry doesn't give NULL if the list is empty...

 I'm not sure how to fix this. Any ideas?

 Regards,
 Arnout