problem with signal handling and threads (fbsd49R)

[Daniel Eischen]

On Thu, 8 Jan 2004, rmkml wrote:

> Hi,
> 
> I've got a problem with signal handling and threads.
> I've reproduced the problem in a simple code.
> Description of program:
>  install a signal  handler SIGINT.
>  create a thread that do nothing except waiting.
>  main thread use poll to wait forever [ poll(,,-1) ].
>  user has too crtl-C to interrupt poll
>  after 5 ctrl-C, loop is over and main-thread signals sub-thread to
> stops.
> 
> In fact, it appears not to work correctly: after one ctrl-C, user has to
> press ctrl-C twice before poll returns with errno=EINTR !!
> If the thread creation is removed from code, the expected behavior is
> seen : the program works fine.
> 
> If I replace the poll by sigsuspend() the program works fine too.
> 
> Is there something wrong with poll function ?

No, it's your program.  Why do you think the signal will
only be delivered to the main thread and not the other
(run) thread?  If you want a particular thread to receive
a signal, then you had better set up signal masks for
all threads appropriately (or use sigwait()).