On SP systems, like bluhm@'s armv7 regression machine, the kern/ptrace2 test is failing due to a subtle behavior. Diff below makes it pass.
http://bluhm.genua.de/regress/results/2021-03-19T15%3A17%3A02Z/logs/sys/kern/ptrace2/make.log The failing test does a fork(2) and the parent issues a PT_ATTACH on the child before it has been scheduled for the first time. Then the parent goes to sleep in waitpid() and when the child starts executing the check below overwrites the ptrace(2)-received SIGSTOP by a SIGTRAP. This scenario doesn't seem to happen on MP machine because the child starts to execute itself on a different core right after sys_fork() is finished. What is the purpose of this check? Should it be relaxed or removed? Index: kern/kern_fork.c =================================================================== RCS file: /cvs/src/sys/kern/kern_fork.c,v retrieving revision 1.234 diff -u -p -r1.234 kern_fork.c --- kern/kern_fork.c 15 Feb 2021 09:35:59 -0000 1.234 +++ kern/kern_fork.c 20 Mar 2021 11:59:18 -0000 @@ -86,9 +86,6 @@ fork_return(void *arg) { struct proc *p = (struct proc *)arg; - if (p->p_p->ps_flags & PS_TRACED) - psignal(p, SIGTRAP); - child_return(p); }
