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Date:      Fri, 24 Apr 2020 13:29:08 +0000 (UTC)
From:      Kyle Evans <kevans@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org
Subject:   svn commit: r360257 - stable/12/tests/sys/kqueue/libkqueue
Message-ID:  <202004241329.03ODT8qt076691@repo.freebsd.org>
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Author: kevans
Date: Fri Apr 24 13:29:08 2020
New Revision: 360257
URL: https://svnweb.freebsd.org/changeset/base/360257

Log:
  MFC r360033, r360108: better precision in kqueue timer tests
  
  r360033:
  tests: kqueue: use a more precise timer for the NOTE_ABSTIME test
  
  Originally noticed while attempting to run the kqueue tests under
  qemu-user-static, this apparently just happens sometimes when running in a
  jail in general -- the timer will fire off "too early," but it's really just
  the result of imprecise measurements (noted by cem).
  
  Kicking this over to NOTE_USECONDS still tests the correct thing while
  allowing it to work more consistently; a basic sanity test reveals that we
  often end up coming in just less than 200 microseconds after the timer
  fired off.
  
  r360108:
  tests: kqueue: fix some issues with now() on ILP32 platforms
  
  There were ultimately two separate problems here:
  - a 32-bit long cannot represent microseconds since 1970 (noted by ian)
  - time_t is 32-bit on i386, so now() was wrong anyways even with the correct
    return type.
  
  For the first, just explicitly use a uint64_t for now() and all of the
  callers. For the second, we need to explicitly cast tv_sec to uint64_t
  before it gets multiplied in the SEC_TO_US macro. Casting this instance
  rather than generally in the macro was arbitrarily chosen simply because all
  other uses are converting small relative time values.
  
  The tests now pass on i386, at least; presumably other ILP32 will be fine
  now as well.

Modified:
  stable/12/tests/sys/kqueue/libkqueue/timer.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/tests/sys/kqueue/libkqueue/timer.c
==============================================================================
--- stable/12/tests/sys/kqueue/libkqueue/timer.c	Fri Apr 24 13:25:02 2020	(r360256)
+++ stable/12/tests/sys/kqueue/libkqueue/timer.c	Fri Apr 24 13:29:08 2020	(r360257)
@@ -30,13 +30,14 @@
 /* Get the current time with microsecond precision. Used for
  * sub-second timing to make some timer tests run faster.
  */
-static long
+static uint64_t
 now(void)
 {
     struct timeval tv;
 
     gettimeofday(&tv, NULL);
-    return SEC_TO_US(tv.tv_sec) + tv.tv_usec;
+    /* Promote potentially 32-bit time_t to uint64_t before conversion. */
+    return SEC_TO_US((uint64_t)tv.tv_sec) + tv.tv_usec;
 }
 
 /* Sleep for a given number of milliseconds. The timeout is assumed to
@@ -216,17 +217,17 @@ test_abstime(void)
 {
     const char *test_id = "kevent(EVFILT_TIMER, EV_ONESHOT, NOTE_ABSTIME)";
     struct kevent kev;
-    time_t start;
-    time_t stop;
-    const int timeout = 3;
+    uint64_t end, start, stop;
+    const int timeout_sec = 3;
 
     test_begin(test_id);
 
     test_no_kevents();
 
-    start = time(NULL);
+    start = now();
+    end = start + SEC_TO_US(timeout_sec);
     EV_SET(&kev, vnode_fd, EVFILT_TIMER, EV_ADD | EV_ONESHOT,
-      NOTE_ABSTIME | NOTE_SECONDS, start + timeout, NULL);
+      NOTE_ABSTIME | NOTE_USECONDS, end, NULL);
     if (kevent(kqfd, &kev, 1, NULL, 0, NULL) < 0)
         err(1, "%s", test_id);
 
@@ -235,10 +236,10 @@ test_abstime(void)
     kev.data = 1;
     kev.fflags = 0;
     kevent_cmp(&kev, kevent_get(kqfd));
-    stop = time(NULL);
-    if (stop < start + timeout)
-        err(1, "too early %jd %jd", (intmax_t)stop, (intmax_t)(start + timeout));
 
+    stop = now();
+    if (stop < end)
+        err(1, "too early %jd %jd", (intmax_t)stop, (intmax_t)end);
     /* Check if the event occurs again */
     sleep(3);
     test_no_kevents();
@@ -252,7 +253,7 @@ test_update(void)
     const char *test_id = "kevent(EVFILT_TIMER (UPDATE), EV_ADD | EV_ONESHOT)";
     struct kevent kev;
     long elapsed;
-    long start;
+    uint64_t start;
 
     test_begin(test_id);
 
@@ -297,7 +298,7 @@ test_update_equal(void)
     const char *test_id = "kevent(EVFILT_TIMER (UPDATE=), EV_ADD | EV_ONESHOT)";
     struct kevent kev;
     long elapsed;
-    long start;
+    uint64_t start;
 
     test_begin(test_id);
 
@@ -341,7 +342,7 @@ test_update_expired(void)
     const char *test_id = "kevent(EVFILT_TIMER (UPDATE EXP), EV_ADD | EV_ONESHOT)";
     struct kevent kev;
     long elapsed;
-    long start;
+    uint64_t start;
 
     test_begin(test_id);
 
@@ -392,8 +393,7 @@ test_update_periodic(void)
     const char *test_id = "kevent(EVFILT_TIMER (UPDATE), periodic)";
     struct kevent kev;
     long elapsed;
-    long start;
-    long stop;
+    uint64_t start, stop;
 
     test_begin(test_id);
 
@@ -450,8 +450,7 @@ test_update_timing(void)
     int iteration;
     int sleeptime;
     long elapsed;
-    long start;
-    long stop;
+    uint64_t start, stop;
 
     test_begin(test_id);

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