PERFORCE change 56496 for review

[David Xu]

http://perforce.freebsd.org/chv.cgi?CH=56496

Change 56496 by davidxu at davidxu_alona on 2004/07/05 11:47:36

	Allow multiple threads to report debug event at same time,
	the last thread will win the race, and others will retry,
	debugger has chance to select a thread to be replied.

Affected files ...

.. //depot/projects/davidxu_ksedbg/src/sys/kern/kern_sig.c#5 edit
.. //depot/projects/davidxu_ksedbg/src/sys/sys/proc.h#4 edit

Differences ...

==== //depot/projects/davidxu_ksedbg/src/sys/kern/kern_sig.c#5 (text+ko) ====

@@ -2005,16 +2005,39 @@
 {
 	struct proc *p = td->td_proc;
 	struct thread *td0;
-	int newsig;
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK,
 	    &p->p_mtx.mtx_object, "Stopping for traced signal");
 
-	while (P_SHOULDSTOP(p)) {
-		if (p->p_flag & P_SINGLE_EXIT)
+	mtx_lock_spin(&sched_lock);
+	td->td_flags |= TDF_XSIG;
+	mtx_unlock_spin(&sched_lock);
+	td->td_xsig = sig;
+	while (td->td_flags & TDF_XSIG) {
+		if (p->p_flag & P_SINGLE_EXIT) {
+			mtx_lock_spin(&sched_lock);
+			td->td_flags &= ~TDF_XSIG;
+			mtx_unlock_spin(&sched_lock);
 			return (sig);
+		}
+		/*
+		 * Just make wait() to work, the last stopped thread
+		 * will win.
+		 */
+		p->p_xstat = sig;
+		p->p_xthread = td;
+		p->p_flag |= (P_STOPPED_SIG|P_STOPPED_TRACE);
 		mtx_lock_spin(&sched_lock);
+		FOREACH_THREAD_IN_PROC(p, td0) {
+			if (TD_IS_SLEEPING(td0) &&
+			    (td0->td_flags & TDF_SINTR) &&
+			    !TD_IS_SUSPENDED(td0)) {
+				thread_suspend_one(td0);
+			} else if (td != td0) {
+				td0->td_flags |= TDF_ASTPENDING;
+			}
+		}
 		thread_stopped(p);
 		thread_suspend_one(td);
 		PROC_UNLOCK(p);
@@ -2024,33 +2047,7 @@
 		PICKUP_GIANT();
 		PROC_LOCK(p);
 	}
-	p->p_xstat = sig;
-	p->p_xthread = td;
-	p->p_flag |= (P_STOPPED_SIG|P_STOPPED_TRACE);
-	mtx_lock_spin(&sched_lock);
-	FOREACH_THREAD_IN_PROC(p, td0) {
-		if (TD_IS_SLEEPING(td0) &&
-		    (td0->td_flags & TDF_SINTR) &&
-		    !TD_IS_SUSPENDED(td0)) {
-			thread_suspend_one(td0);
-		} else if (td != td0) {
-			td0->td_flags |= TDF_ASTPENDING;
-		}
-	}
-	thread_stopped(p);
-	thread_suspend_one(td);
-	PROC_UNLOCK(p);
-	DROP_GIANT();
-	mi_switch(SW_INVOL, NULL);
-	mtx_unlock_spin(&sched_lock);
-	PICKUP_GIANT();
-	PROC_LOCK(p);
-	newsig = p->p_xstat;
-	p->p_xstat = newsig;
-	mtx_lock_spin(&sched_lock);
-	thread_unsuspend(p);
-	mtx_unlock_spin(&sched_lock);
-	return (newsig);
+	return (td->td_xsig);
 }
 
 /*

==== //depot/projects/davidxu_ksedbg/src/sys/sys/proc.h#4 (text+ko) ====

@@ -303,7 +303,7 @@
 	volatile u_int	td_generation;	/* (k) Enable detection of preemption */
 	stack_t		td_sigstk;	/* (k) Stack ptr and on-stack flag. */
 	int		td_kflags;	/* (c) Flags for KSE threading. */
-
+	int		td_xsig;	/* (c) Signal for ptrace */
 #define	td_endzero td_base_pri
 
 /* Copied during fork1() or thread_sched_upcall(). */
@@ -354,6 +354,7 @@
 #define	TDF_OWEUPC	0x008000 /* Owe thread an addupc() call at next AST. */
 #define	TDF_NEEDRESCHED	0x010000 /* Thread needs to yield. */
 #define	TDF_NEEDSIGCHK	0x020000 /* Thread may need signal delivery. */
+#define	TDF_XSIG	0x040000 /* Thread is exchanging signal under traced */ 
 #define	TDF_UMTXWAKEUP	0x080000 /* Libthr thread must not sleep on a umtx. */
 #define	TDF_THRWAKEUP	0x100000 /* Libthr thread must not suspend itself. */