Thu Jan 30 12:36:38 2020 UTC ()

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diff -r1.74 -r1.75 src/sys/kern/sys_lwp.c

--- src/sys/kern/sys_lwp.c 2020/01/29 15:47:52	1.74
+++ src/sys/kern/sys_lwp.c 2020/01/30 12:36:38	1.75

 @@ -1,14 +1,14 @@
-/*	$NetBSD: sys_lwp.c,v 1.74 2020/01/29 15:47:52 ad Exp $	*/
+/*	$NetBSD: sys_lwp.c,v 1.75 2020/01/30 12:36:38 ad Exp $	*/
 /*-
  * Copyright (c) 2001, 2006, 2007, 2008, 2019, 2020 The NetBSD Foundation, Inc.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Nathan J. Williams, and Andrew Doran.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
 @@ -25,27 +25,27 @@
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 /*
  * Lightweight process (LWP) system calls.  See kern_lwp.c for a description
  * of LWPs.
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_lwp.c,v 1.74 2020/01/29 15:47:52 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_lwp.c,v 1.75 2020/01/30 12:36:38 ad Exp $");
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/pool.h>
 #include <sys/proc.h>
 #include <sys/types.h>
 #include <sys/syscallargs.h>
 #include <sys/kauth.h>
 #include <sys/kmem.h>
 #include <sys/ptrace.h>
 #include <sys/sleepq.h>
 #include <sys/lwpctl.h>
 #include <sys/cpu.h>
 @@ -470,35 +470,41 @@ lwp_unpark(const lwpid_t *tp, const u_in
 	rw_enter(&p->p_treelock, RW_READER);
 	for (target = 0; target < ntargets; target++) {
 		/*
 		 * We don't bother excluding zombies or idle LWPs here, as
 		 * setting LW_UNPARKED on them won't do any harm.
 		 */
 		id = (uint64_t)(tp[target] - 1);
 		t = radix_tree_lookup_node(&p->p_lwptree, id);
 		if (t == NULL) {
 			error = ESRCH;
 			continue;
+		}
 		/* It may not have parked yet or we may have raced. */
 		lwp_lock(t);
 		if (t->l_syncobj == &lwp_park_syncobj) {
-			/* Releases the LWP lock. */
+			/*
 			 * As expected it's parked, so wake it up.
 			 * lwp_unsleep() will release the LWP lock.
 			 */
 			lwp_unsleep(t, true);
 		} else {
 			/*
-			 * Set the operation pending.  The next call to
+			 * It hasn't parked yet because the wakeup side won
-			 * _lwp_park() will return early.
+			 * the race, or something else has happened to make
 			 * the thread not park.  Why doesn't really matter.
 			 * Set the operation pending, so that the next call
 			 * to _lwp_park() in the LWP returns early.  If it
 			 * turns out to be a spurious wakeup, no harm done.
 			 */
 			t->l_flag |= LW_UNPARKED;
 			lwp_unlock(t);
+		}
+	}
 	rw_exit(&p->p_treelock);
 	return error;
+}
 int
 lwp_park(clockid_t clock_id, int flags, struct timespec *ts)
+{