Date: Thu, 31 Mar 2011 09:58:51 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: Svatopluk Kraus <onwahe@gmail.com> Subject: Re: schedcpu() in /sys/kern/sched_4bsd.c calls thread_lock() on thread with un-initialized td_lock Message-ID: <201103310958.51416.jhb@freebsd.org> In-Reply-To: <AANLkTimEiOW%2BkSZD6n1MHiRou3UWibU6Oy3fr9RO4_O4@mail.gmail.com> References: <AANLkTimEiOW%2BkSZD6n1MHiRou3UWibU6Oy3fr9RO4_O4@mail.gmail.com>
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On Thursday, March 31, 2011 7:32:26 am Svatopluk Kraus wrote:
> Hi,
>
> I've got a page fault (because of NULL td_lock) in
> thread_lock_flags() called from schedcpu() in /sys/kern/sched_4bsd.c
> file. During process fork, new thread is linked to new process which
> is linked to allproc list and both allproc_lock and new process lock
> are unlocked before sched_fork() is called, where new thread td_lock
> is initialized. Only PRS_NEW process status is on sentry but not
> checked in schedcpu().
I think this should fix it:
Index: sched_4bsd.c
===================================================================
--- sched_4bsd.c (revision 220190)
+++ sched_4bsd.c (working copy)
@@ -463,6 +463,10 @@ schedcpu(void)
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
PROC_LOCK(p);
+ if (p->p_state == PRS_NEW) {
+ PROC_UNLOCK(p);
+ continue;
+ }
FOREACH_THREAD_IN_PROC(p, td) {
awake = 0;
thread_lock(td);
--
John Baldwin
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