From 8be8acd7af2d635a3a2a8508546a3bbf6b6190ed Mon Sep 17 00:00:00 2001 From: ed Date: Thu, 22 Oct 2015 09:33:34 +0000 Subject: [PATCH] Add a way to distinguish between forking and thread creation in schedtail. For CloudABI we need to initialize the registers of new threads differently based on whether the thread got created through a fork or through simple thread creation. Add a flag, TDP_FORKING, that is set by do_fork() and cleared by fork_exit(). This can be tested against in schedtail. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D3973 --- sys/kern/kern_fork.c | 3 ++- sys/kern/subr_syscall.c | 3 +++ sys/sys/proc.h | 2 +- 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c index bb35b9b25d8f..1b556be41d01 100644 --- a/sys/kern/kern_fork.c +++ b/sys/kern/kern_fork.c @@ -586,7 +586,7 @@ do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2, * been preserved. */ p2->p_flag |= p1->p_flag & P_SUGID; - td2->td_pflags |= td->td_pflags & TDP_ALTSTACK; + td2->td_pflags |= (td->td_pflags & TDP_ALTSTACK) | TDP_FORKING; SESS_LOCK(p1->p_session); if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) p2->p_flag |= P_CONTROLT; @@ -1023,6 +1023,7 @@ fork_exit(void (*callout)(void *, struct trapframe *), void *arg, if (p->p_sysent->sv_schedtail != NULL) (p->p_sysent->sv_schedtail)(td); + td->td_pflags &= ~TDP_FORKING; } /* diff --git a/sys/kern/subr_syscall.c b/sys/kern/subr_syscall.c index 71f3d5998367..c0763262f74b 100644 --- a/sys/kern/subr_syscall.c +++ b/sys/kern/subr_syscall.c @@ -176,6 +176,9 @@ syscallret(struct thread *td, int error, struct syscall_args *sa) struct proc *p, *p2; int traced; + KASSERT((td->td_pflags & TDP_FORKING) == 0, + ("fork() did not clear TDP_FORKING upon completion")); + p = td->td_proc; /* diff --git a/sys/sys/proc.h b/sys/sys/proc.h index 5e8acc6147ca..eff28b40365b 100644 --- a/sys/sys/proc.h +++ b/sys/sys/proc.h @@ -446,7 +446,7 @@ do { \ #define TDP_RESETSPUR 0x04000000 /* Reset spurious page fault history. */ #define TDP_NERRNO 0x08000000 /* Last errno is already in td_errno */ #define TDP_UIOHELD 0x10000000 /* Current uio has pages held in td_ma */ -#define TDP_UNUSED29 0x20000000 /* --available-- */ +#define TDP_FORKING 0x20000000 /* Thread is being created through fork() */ #define TDP_EXECVMSPC 0x40000000 /* Execve destroyed old vmspace */ /*