pthread_cancel / sleep change in behaviour

Konstantin Belousov kostikbel at gmail.com
Fri Sep 4 08:19:10 UTC 2015


On Fri, Sep 04, 2015 at 08:37:40AM +0800, Erich Dollansky wrote:
> Hi,
> 
> On Thu, 3 Sep 2015 13:43:51 +0300
> Konstantin Belousov <kostikbel at gmail.com> wrote:
> > On Thu, Sep 03, 2015 at 06:33:53PM +0800, Erich Dollansky wrote:
> > > On Thu, 3 Sep 2015 11:19:47 +0300
> > > Konstantin Belousov <kostikbel at gmail.com> wrote:
> > > > On Thu, Sep 03, 2015 at 08:00:47AM +0800, Erich Dollansky wrote:
> > > > > Is this change of behaviour a feature or a bug?
> > > > Provide a minimal example demonstrating the issue.
> > > while preparing the example I found the source of the problem. We
> > > have to block all signals for some reason. The handling for
> > > 
> > > signal (SIGTHR, SIG_IGN);
> > > 
> > > seems to have changed. The moment I remove above's line from the
> > > code, the program works. There is no difference when the programs
> > > runs on machines prior mid November 2014.
> > > 
> > Err, this is a bug, probably both in your program (user code must not
> > twiddle with SIGCANCEL) and in libc. The later, I believe, was fixed
> 
> I just ran the same binary on:
> 
> FreeBSD B85M-HD3-0.alogt.com 11.0-CURRENT FreeBSD 11.0-CURRENT #5
> r287425: Thu Sep  3 21:44:16 WITA 2015
> erich at B85M-HD3-0.alogt.com:/usr/obj/usr/src/sys/B85M-HD3  amd64
> 
> and it works there.
> 
> So, it is just a matter of time until the fix finds its way back to 10?
Yes, should be several days timeframe.

> 
> Of course, I do not ignore the signal now in the application anymore.
> The application then works as expected on 10.2 STABLE.
Well, the consequence of the bug, which affected you, is that it was
allowed for the applications to ignore SIGCANCEL. With the bug fixed,
the signal(SIGCANCEL, anything) becomes nop.


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