- Change CURSIG() and postsig() to require that the proc lock is held

  rather than grabbing it and releasing it themselves.  This allows callers
  of these functions to get the lock to close race conditions.
- Grab Giant around ktrace in postsig.
- Count the switches performed on SIGSTOP's as involuntary context switches
  in the resource usage stats.

Reported by:	tegge (signal race), bde (missing csw stats)

1 files changed, 10 insertions, 9 deletions

diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 5c43d06..82d2c73 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -172,19 +172,15 @@ int
 CURSIG(struct proc *p)
 {
 	sigset_t tmpset;
-	int r = 0;
 
-	PROC_LOCK(p);
+	PROC_LOCK_ASSERT(p, MA_OWNED);
 	if (SIGISEMPTY(p->p_siglist))
-		goto out;
+		return (0);
 	tmpset = p->p_siglist;
 	SIGSETNAND(tmpset, p->p_sigmask);
 	if (SIGISEMPTY(tmpset) && (p->p_flag & P_TRACED) == 0)
-		goto out;
-	r = issignal(p);
-out:
-	PROC_UNLOCK(p);
-	return (r);
+		return (0);
+	return (issignal(p));
 }
 
 static __inline int
@@ -1386,6 +1382,7 @@ issignal(p)
 				stop(p);
 				PROC_UNLOCK_NOSWITCH(p);
 				DROP_GIANT_NOSWITCH();
+				p->p_stats->p_ru.ru_nivcsw++;
 				mi_switch();
 				mtx_unlock_spin(&sched_lock);
 				PICKUP_GIANT();
@@ -1464,6 +1461,7 @@ issignal(p)
 				stop(p);
 				PROC_UNLOCK_NOSWITCH(p);
 				DROP_GIANT_NOSWITCH();
+				p->p_stats->p_ru.ru_nivcsw++;
 				mi_switch();
 				mtx_unlock_spin(&sched_lock);
 				PICKUP_GIANT();
@@ -1536,10 +1534,12 @@ postsig(sig)
 
 	KASSERT(sig != 0, ("postsig"));
 
+	PROC_LOCK_ASSERT(p, MA_OWNED);
 #ifdef KTRACE
+	PROC_UNLOCK(p);
 	mtx_lock(&Giant);
-#endif
 	PROC_LOCK(p);
+#endif
 	ps = p->p_sigacts;
 	SIGDELSET(p->p_siglist, sig);
 	action = ps->ps_sigact[_SIG_IDX(sig)];
@@ -1603,6 +1603,7 @@ postsig(sig)
 		}
 		PROC_UNLOCK(p);
 		(*p->p_sysent->sv_sendsig)(action, sig, &returnmask, code);
+		PROC_LOCK(p);
 	}
 }