Date: Fri, 25 Jan 2008 11:00:05 GMT From: Gary Stanley <gary@velocity-servers.net> To: freebsd-threads@FreeBSD.org Subject: Re: threads/119920: fork broken in libpthread Message-ID: <200801251100.m0PB05sM043838@freefall.freebsd.org>
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The following reply was made to PR threads/119920; it has been noted by GNATS.
From: Gary Stanley <gary@velocity-servers.net>
To: bug-followup@FreeBSD.org
Cc:
Subject: Re: threads/119920: fork broken in libpthread
Date: Fri, 25 Jan 2008 05:50:28 -0500
Can you try this patch? I ported it from some mail regarding this
issue on threads@
diff -ur lib/libpthread/thread/thr_kern.c lib/libpthread/thread/thr_kern.c
--- lib/libpthread/thread/thr_kern.c 2006-03-16 23:29:07.000000000 +0000
+++ lib/libpthread/thread/thr_kern.c 2008-01-25 10:33:23.000000000 +0000
@@ -345,6 +345,17 @@
_LCK_SET_PRIVATE2(&curthread->kse->k_lockusers[i], NULL);
}
curthread->kse->k_locklevel = 0;
+
+ /*
+ * Reinitialize the thread and signal locks so that
+ * sigaction() will work after a fork().
+ */
+ _lock_reinit(&curthread->lock, LCK_ADAPTIVE, _thr_lock_wait,
+ _thr_lock_wakeup);
+ _lock_reinit(&_thread_signal_lock, LCK_ADAPTIVE, _kse_lock_wait,
+ _kse_lock_wakeup);
+
+
_thr_spinlock_init();
if (__isthreaded) {
_thr_rtld_fini();
@@ -354,6 +365,20 @@
curthread->kse->k_kcb->kcb_kmbx.km_curthread = NULL;
curthread->attr.flags |= PTHREAD_SCOPE_SYSTEM;
+ /*
+ * After a fork, it is possible that an upcall occurs in
+ * the parent KSE that fork()'d before the child process
+ * is fully created and before its vm space is copied.
+ * During the upcall, the tcb is set to null or to another
+ * thread, and this is what gets copied in the child process
+ * when the vm space is cloned sometime after the upcall
+ * occurs. Note that we shouldn't have to set the kcb, but
+ * we do it for completeness.
+ */
+ _kcb_set(curthread->kse->k_kcb);
+ _tcb_set(curthread->kse->k_kcb, curthread->tcb);
+
+
/* After a fork(), there child should have no pending signals. */
sigemptyset(&curthread->sigpend);
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