Re: Scheduler: SIGSTOP on multi threaded processes

From: Miquel van Smoorenburg
Date: Thu May 05 2005 - 17:05:42 EST


In article <Pine.LNX.4.61.0505050814340.24130@xxxxxxxxxxxxxxxxxx>,
Richard B. Johnson <linux-os@xxxxxxxxxxxx> wrote:
>
>I don't think the kernel handler gets a chance to do anything
>because SYS-V init installs its own handler(s). There are comments
>about Linux misbehavior in the code. It turns out that I was
>right about SIGSTOP and SIGCONT...

No, you're confused. Sysvinit catches SIGTSTP and SIGCONT (not SIGSTOP)
because pid #1 is special - unlike all other processes, SIG_DFL for
pid #1 is equal to SIG_IGN.

And remember - signal handlers are not inherited (how could they be..)
so there is no such thing as "init installing a signal handler
for all processes".

Right now you should go out and buy a copy of the Stevens book,
"Advanced programming in the Unix enviroment", and study it.

Mike.

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