RE: fork(): parent or child should run first?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> The following problem may be simple for you, so I hope someone can answer
> here. We've got a complex software using child processes and a table
> to keep data of them together, like this:
>
> childs[n].pid=fork();
>
> where "n" is an integer contains a free "slot" in the childs struct array.
>
> I also handle SIGCHLD in the parent and signal handler  searches
> the childs
> array for the pid returned by waitpid(). However here is my problem. The
> child process can be fast, ie exits before scheduler of the kernel give
> chance the parent process to run, so storing pid into childs[n].pid in the
> parent context is not done yet. Child may exit, than scheduler
> gives control
[snip]

	There are a lot of things you should not do in a signal handler, this is
one of them. There are a lot of possible solutions. My recommendation would
be to handle the death of a child from a safe context, rather than from a
signal handler. For example, the SIGCHLD handler could just set a volatile
variable to 'true' and then the code could notice that from a safe context
and loop on 'waitpid', reaping all dead children.

	DS


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux