[Nut-upsdev] nut-scanner pthread issue

[Michal Hlavinka]

 > I am not sure your patch is the right way to fix. I guess it's 
crashing because pthread_t is some kind of pointer on your system.

Right, on Linux, pthread_t is a pointer.

 > I did not find something saying that an implementation of pthread 
forbid thre thread ID to be 0 (correct me if I am wrong).

I did not find any documentation neither


 > setting the appropriate nutscan_avail_* variable to 0 might be a 
better way.

yes, it'll fix the problem too

> ________________________________________
> From: nut-upsdev-bounces+fredericbohe=eaton.com at lists.alioth.debian.org [nut-upsdev-bounces+fredericbohe=eaton.com at lists.alioth.debian.org] on behalf of Michal Hlavinka [mhlavink at redhat.com]
> Sent: Thursday, September 06, 2012 3:24 PM
> To: NUT Developers
> Subject: [Nut-upsdev] nut-scanner pthread issue
>
> Hi,
>
> the terminating part of nut-scanner can crash in pthread code, because
> some threads won't exist. For example snmp part:
>
> ==============================
>          if( allow_snmp && nutscan_avail_snmp ) {
>                  if( start_ip == NULL ) {
>                          printq(quiet,"No start IP, skipping SNMP\n");
>                  }
>                  else {
>                          printq(quiet,"Scanning SNMP bus.\n");
> #ifdef HAVE_PTHREAD
>                          if( pthread_create(&thread[TYPE_SNMP],NULL,run_snmp,&snmp_sec)) {
>                                  nutscan_avail_snmp = 0;
>                          }
> #else
>                          dev[TYPE_SNMP] = nutscan_scan_snmp(start_ip,end_ip,timeout,&snmp_sec);
> #endif /* HAVE_PTHREAD */
>                  }
>          }
> ==============================
> if start_ip==NULL, pthread is not created, but later...
>
>          if( allow_snmp && nutscan_avail_snmp && thread[TYPE_SNMP]) {
>                  pthread_join(thread[TYPE_SNMP],NULL);
>          }
>
> it calls pthread_join with threan[TYPE_SNMP]==0,
> pthread_join(0, ?) behaviour is undefined, on my system undefined=crashes.
>
> I used attached patch to get rid of it.
>
> Cheers,
> Michal
>
> /me is back from vacation and going to another one tmrw, so I won't be
> reachable for some time (again)
>