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GET /api/patches/2231224/?format=api
{ "id": 2231224, "url": "http://patchwork.ozlabs.org/api/patches/2231224/?format=api", "web_url": "http://patchwork.ozlabs.org/project/rtc-linux/patch/20260430120313.4078185-1-wakel@google.com/", "project": { "id": 9, "url": "http://patchwork.ozlabs.org/api/projects/9/?format=api", "name": "Linux RTC development", "link_name": "rtc-linux", "list_id": "linux-rtc.vger.kernel.org", "list_email": "linux-rtc@vger.kernel.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260430120313.4078185-1-wakel@google.com>", "list_archive_url": null, "date": "2026-04-30T12:03:13", "name": "selftests: rtc: fix flaky date_read_loop test", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "f79befdcc834c93aba0936a12e1bbf305dc3a6a7", "submitter": { "id": 92108, "url": "http://patchwork.ozlabs.org/api/people/92108/?format=api", "name": "Wake Liu", "email": "wakel@google.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/rtc-linux/patch/20260430120313.4078185-1-wakel@google.com/mbox/", "series": [ { "id": 502288, "url": "http://patchwork.ozlabs.org/api/series/502288/?format=api", "web_url": "http://patchwork.ozlabs.org/project/rtc-linux/list/?series=502288", "date": "2026-04-30T12:03:13", "name": "selftests: rtc: fix flaky date_read_loop test", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/502288/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2231224/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2231224/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linux-rtc+bounces-6456-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-rtc@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256\n header.s=20251104 header.b=eoIk2JN9;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; 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Thu, 30\n Apr 2026 05:03:22 -0700 (PDT)", "Date": "Thu, 30 Apr 2026 20:03:13 +0800", "Precedence": "bulk", "X-Mailing-List": "linux-rtc@vger.kernel.org", "List-Id": "<linux-rtc.vger.kernel.org>", "List-Subscribe": "<mailto:linux-rtc+subscribe@vger.kernel.org>", "List-Unsubscribe": "<mailto:linux-rtc+unsubscribe@vger.kernel.org>", "Mime-Version": "1.0", "X-Mailer": "git-send-email 2.54.0.545.g6539524ca2-goog", "Message-ID": "<20260430120313.4078185-1-wakel@google.com>", "Subject": "[PATCH] selftests: rtc: fix flaky date_read_loop test", "From": "Wake Liu <wakel@google.com>", "To": "Alexandre Belloni <alexandre.belloni@bootlin.com>,\n Shuah Khan <shuah@kernel.org>", "Cc": "linux-rtc@vger.kernel.org, linux-kselftest@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org, Wake Liu <wakel@google.com>", "Content-Type": "text/plain; charset=\"UTF-8\"" }, "content": "The test case rtc.date_read_loop in rtctest.c fails intermittently because\nit checks that the RTC time does not advance by more than 1 second per loop\niteration. However, the loop sleeps for 11ms via nanosleep(), and if the\ntest thread is descheduled by the OS scheduler (e.g., under heavy system\nload in a VM), more than 1 second can elapse between consecutive RTC reads.\nThis causes the next RTC time read to be 2 or more seconds ahead of the\nprevious read, triggering a test assertion failure.\n\nTo make the test more resilient against OS scheduling delays, measure the\nreal elapsed time between iterations using a monotonic clock\n(clock_gettime(CLOCK_MONOTONIC)), and compute the actual number of seconds\nelapsed (delta_s) between consecutive RTC reads. Then dynamically adjust\nthe assertion to:\nASSERT_GE(prev_rtc_read + delta_s + 1, rtc_read);\n\nSigned-off-by: Wake Liu <wakel@google.com>\n---\n tools/testing/selftests/rtc/rtctest.c | 11 +++++++++--\n 1 file changed, 9 insertions(+), 2 deletions(-)", "diff": "diff --git a/tools/testing/selftests/rtc/rtctest.c b/tools/testing/selftests/rtc/rtctest.c\nindex 8047d9879039..54eb5c255a45 100644\n--- a/tools/testing/selftests/rtc/rtctest.c\n+++ b/tools/testing/selftests/rtc/rtctest.c\n@@ -116,6 +116,7 @@ TEST_F_TIMEOUT(rtc, date_read_loop, READ_LOOP_DURATION_SEC + 2) {\n \tlong iter_count = 0;\n \tstruct rtc_time rtc_tm;\n \ttime_t start_rtc_read, prev_rtc_read;\n+\tstruct timespec prev_mono, cur_mono;\n \n \tif (self->fd == -1 && errno == ENOENT)\n \t\tSKIP(return, \"Skipping test since %s does not exist\", rtc_file);\n@@ -126,25 +127,31 @@ TEST_F_TIMEOUT(rtc, date_read_loop, READ_LOOP_DURATION_SEC + 2) {\n \n \trc = ioctl(self->fd, RTC_RD_TIME, &rtc_tm);\n \tASSERT_NE(-1, rc);\n+\tclock_gettime(CLOCK_MONOTONIC, &prev_mono);\n \tstart_rtc_read = rtc_time_to_timestamp(&rtc_tm);\n \tprev_rtc_read = start_rtc_read;\n \n \tdo {\n \t\ttime_t rtc_read;\n+\t\ttime_t delta_s = 0;\n \n \t\trc = ioctl(self->fd, RTC_RD_TIME, &rtc_tm);\n \t\tASSERT_NE(-1, rc);\n+\t\tclock_gettime(CLOCK_MONOTONIC, &cur_mono);\n \n \t\trtc_read = rtc_time_to_timestamp(&rtc_tm);\n+\t\tdelta_s = cur_mono.tv_sec - prev_mono.tv_sec;\n+\n \t\t/* Time should not go backwards */\n \t\tASSERT_LE(prev_rtc_read, rtc_read);\n-\t\t/* Time should not increase more then 1s at a time */\n-\t\tASSERT_GE(prev_rtc_read + 1, rtc_read);\n+\t\t/* Time should not increase more then elapsed time + 1s */\n+\t\tASSERT_GE(prev_rtc_read + delta_s + 1, rtc_read);\n \n \t\t/* Sleep 11ms to avoid killing / overheating the RTC */\n \t\tnanosleep_with_retries(READ_LOOP_SLEEP_MS * 1000000);\n \n \t\tprev_rtc_read = rtc_read;\n+\t\tprev_mono = cur_mono;\n \t\titer_count++;\n \t} while (prev_rtc_read <= start_rtc_read + READ_LOOP_DURATION_SEC);\n \n", "prefixes": [] }