diff options
Diffstat (limited to 'sysdeps/mach/hurd/fork.c')
| -rw-r--r-- | sysdeps/mach/hurd/fork.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/sysdeps/mach/hurd/fork.c b/sysdeps/mach/hurd/fork.c index 2527964..6fadb3d 100644 --- a/sysdeps/mach/hurd/fork.c +++ b/sysdeps/mach/hurd/fork.c @@ -1,4 +1,4 @@ -/* Copyright (C) 1994, 1995 Free Software Foundation, Inc. +/* Copyright (C) 1994, 1995, 1996 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -121,7 +121,6 @@ __fork (void) __spin_lock (&_hurd_ports[i].lock); ports_locked = 1; - *(volatile task_t *) &__mach_task_self_; /* XXX work around kernel bug */ /* Stop all other threads while copying the address space, so nothing changes. */ @@ -130,6 +129,25 @@ __fork (void) { stopped = 1; +#define XXX_KERNEL_PAGE_FAULT_BUG /* XXX work around page fault bug in mk */ + +#ifdef XXX_KERNEL_PAGE_FAULT_BUG + /* Gag me with a pitchfork. + The bug scenario is this: + + - The page containing __mach_task_self_ is paged out. + - The signal thread was faulting on that page when we + suspended it via proc_dostop. It holds some lock, or set + some busy bit, or somesuch. + - Now this thread faults on that same page. + - GRATUIOUS DEADLOCK + + We can break the deadlock by aborting the thread that faulted + first, which if the bug happened was the signal thread because + it is the only other thread and we just suspended it. + */ + __thread_abort (_hurd_msgport_thread); +#endif /* Create the child task. It will inherit a copy of our memory. */ err = __task_create (__mach_task_self (), 1, &newtask); } |