From nobody Tue Dec 2 01:03:57 2025 Received: from mailgw.kylinos.cn (mailgw.kylinos.cn [124.126.103.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 723703002A3; Mon, 24 Nov 2025 12:39:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=124.126.103.232 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763987969; cv=none; b=dNTaHqpIy0DWY8Yjc4qM1G6en00SvMpV9lKbgbf3AQQYcIUsbqfM1CjH8DQk4Pg18Bwzj/hMThhiVz1Qs0AgznOz/RXQ0ncEen1gT9TZU1gUNU9IuGfXWvSeOE4xzoJKNunb/zS8DVTXXw6e/uqUuQrPCyXvm9RKxL47fI1gZuQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763987969; c=relaxed/simple; bh=szqf3Kx+BUT+AouG3NOcTxdXuFk3oM/DtXY+gzj1CM4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=lCbsBG7U4TPEgkUtn204W+vkVdwW/WY44BGTgwiH3XCor8uYaSWIOjCeZ8MkLRvrJ5ji7BQ3+PnSD+u6lsNUIYAJ0dogUva/aRbfDYmrKqwBjQi5mdIUMF3vNP+CDjY/m5JPbHquAaXoeL5yQp13bhR3KD+KVLR6ymB4V3iAU4w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn; spf=pass smtp.mailfrom=kylinos.cn; arc=none smtp.client-ip=124.126.103.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kylinos.cn X-UUID: 98483984c93211f0a38c85956e01ac42-20251124 X-CTIC-Tags: HR_CC_COUNT, HR_CC_DOMAIN_COUNT, HR_CC_NAME, HR_CC_NO_NAME, HR_CTE_8B HR_CTT_TXT, HR_DATE_H, HR_DATE_WKD, HR_DATE_ZONE, HR_FROM_NAME HR_SJ_DIGIT_LEN, HR_SJ_LANG, HR_SJ_LEN, HR_SJ_LETTER, HR_SJ_NOR_SYM HR_SJ_PHRASE, HR_SJ_PHRASE_LEN, HR_SJ_WS, HR_TO_COUNT, HR_TO_DOMAIN_COUNT HR_TO_NO_NAME, IP_TRUSTED, SRC_TRUSTED, DN_TRUSTED, SA_EXISTED SN_EXISTED, SPF_NOPASS, DKIM_NOPASS, DMARC_NOPASS, CIE_GOOD CIE_GOOD_SPF, GTI_FG_BS, GTI_RG_INFO, GTI_C_BU, AMN_GOOD ABX_MISS_RDNS X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.6,REQID:42b03b5e-27eb-45ad-9959-30113448a8c4,IP:10,U RL:0,TC:0,Content:-5,EDM:0,RT:0,SF:-5,FILE:0,BULK:0,RULE:Release_Ham,ACTIO N:release,TS:0 X-CID-INFO: VERSION:1.3.6,REQID:42b03b5e-27eb-45ad-9959-30113448a8c4,IP:10,URL :0,TC:0,Content:-5,EDM:0,RT:0,SF:-5,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:0 X-CID-META: VersionHash:a9d874c,CLOUDID:fbe2a9042fa2bbbafeb5aba0e34aac7c,BulkI D:251124203921M1CZFT1B,BulkQuantity:0,Recheck:0,SF:17|19|38|66|78|81|82|10 2|127|850|898,TC:nil,Content:0|15|50,EDM:-3,IP:-2,URL:0,File:nil,RT:nil,Bu lk:nil,QS:nil,BEC:nil,COL:0,OSI:0,OSA:0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR: 0,BRE:0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR,TF_CID_SPAM_FAS,TF_CID_SPAM_FSD X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: 98483984c93211f0a38c85956e01ac42-20251124 X-User: zhangguopeng@kylinos.cn Received: from localhost.localdomain [(223.70.159.239)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_256_GCM_SHA384 256/256) with ESMTP id 149211058; Mon, 24 Nov 2025 20:39:18 +0800 From: Guopeng Zhang To: tj@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, mkoutny@suse.com, muchun.song@linux.dev Cc: lance.yang@linux.dev, shuah@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Guopeng Zhang Subject: [PATCH v4 1/3] selftests: cgroup: Add cg_read_key_long_poll() to poll a cgroup key with retries Date: Mon, 24 Nov 2025 20:38:14 +0800 Message-Id: <20251124123816.486164-2-zhangguopeng@kylinos.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251124123816.486164-1-zhangguopeng@kylinos.cn> References: <20251124123816.486164-1-zhangguopeng@kylinos.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Introduce a new helper function `cg_read_key_long_poll()` in cgroup_util.h. This function polls the specified key in a cgroup file until it matches the= expected value or the retry limit is reached, with configurable wait intervals betwe= en retries. This helper is particularly useful for handling asynchronously updated cgro= up statistics (e.g., memory.stat), where immediate reads may observe stale values, especi= ally on busy systems. It allows tests and other utilities to handle such cases more flexibly. Signed-off-by: Guopeng Zhang Suggested-by: Michal Koutn=C3=BD --- .../selftests/cgroup/lib/cgroup_util.c | 21 +++++++++++++++++++ .../cgroup/lib/include/cgroup_util.h | 5 +++++ 2 files changed, 26 insertions(+) diff --git a/tools/testing/selftests/cgroup/lib/cgroup_util.c b/tools/testi= ng/selftests/cgroup/lib/cgroup_util.c index 44c52f620fda..953835f5da66 100644 --- a/tools/testing/selftests/cgroup/lib/cgroup_util.c +++ b/tools/testing/selftests/cgroup/lib/cgroup_util.c @@ -168,6 +168,27 @@ long cg_read_key_long(const char *cgroup, const char *= control, const char *key) return atol(ptr + strlen(key)); } =20 +long cg_read_key_long_poll(const char *cgroup, const char *control, + const char *key, long expected, int retries, + useconds_t wait_interval_us) +{ + long val =3D -1; + int i; + + for (i =3D 0; i < retries; i++) { + val =3D cg_read_key_long(cgroup, control, key); + if (val < 0) + return val; + + if (val =3D=3D expected) + break; + + usleep(wait_interval_us); + } + + return val; +} + long cg_read_lc(const char *cgroup, const char *control) { char buf[PAGE_SIZE]; diff --git a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h b/too= ls/testing/selftests/cgroup/lib/include/cgroup_util.h index 7ab2824ed7b5..772f5383ddc7 100644 --- a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h +++ b/tools/testing/selftests/cgroup/lib/include/cgroup_util.h @@ -17,6 +17,8 @@ #define CG_NAMED_NAME "selftest" #define CG_PATH_FORMAT (!cg_test_v1_named ? "0::%s" : (":name=3D" CG_NAMED= _NAME ":%s")) =20 +#define DEFAULT_WAIT_INTERVAL_US (100 * 1000) /* 100 ms */ + /* * Checks if two given values differ by less than err% of their sum. */ @@ -64,6 +66,9 @@ extern int cg_read_strstr(const char *cgroup, const char = *control, extern long cg_read_long(const char *cgroup, const char *control); extern long cg_read_long_fd(int fd); long cg_read_key_long(const char *cgroup, const char *control, const char = *key); +long cg_read_key_long_poll(const char *cgroup, const char *control, + const char *key, long expected, int retries, + useconds_t wait_interval_us); extern long cg_read_lc(const char *cgroup, const char *control); extern int cg_write(const char *cgroup, const char *control, char *buf); extern int cg_open(const char *cgroup, const char *control, int flags); --=20 2.25.1