On Tue, Dec 02, 2008 at 11:41:03PM -0800, Sukadev Bhattiprolu wrote: > Bastian Blank [bastian@xxxxxxxxxxxx] wrote: > | On Mon, Dec 01, 2008 at 01:15:18PM -0800, Sukadev Bhattiprolu wrote: > | > Greg Kurz [gkurz@xxxxxxxxxx] wrote: > | > | On Thu, 2008-11-27 at 02:17 +0100, Bastian Blank wrote: > | > | > On Tue, Nov 25, 2008 at 07:45:28PM -0800, Sukadev Bhattiprolu wrote: > | > | > > Currently task_active_pid_ns is not safe to call after a > | > | > > task becomes a zombie and exit_task_namespaces is called, > | > | > > as nsproxy becomes NULL. > | > | > Why do you need to be able to get the pid namespace from zombie > | > | > processes? > | > After exiting namespaces, the process notifies parent. With new changes > | > to signals (in this patchset), the signal code may need to determine > | > the namespace of sender (the exiting child in this case). > | So the parent of a process with a new pid namespace will never get a > | SIGCHLD? > I am wondering what I said that leads to that conclusion :-) If parent > has a handler the handler will be called as usual otherwise SIGCHLD > will be ignored. You said you need a way to check the namespace of a zombie process. The only signal a zombie can issue is the SIGCHLD to the parent. > | What I read in the kernel source (kernel/signal.c:do_notify_parent, > | include/asm-generic/siginfo.h:CLD_EXITED) is that the exit signals > | (SIGCHLD) are describes as sent by the kernel. > > Yes. Are you suggesting a check like > > if (!is_si_special(info) && !SI_FROMKERNEL(info)) ? > /* must be from user, safe to check ns */ If "is_si_special(info) && SI_FROMKERNEL(info)" is true, there is no need to check anything. The double negations makes this not easier to read. Bastian -- Klingon phaser attack from front!!!!! 100% Damage to life support!!!! _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
