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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1755536541; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fyQY6WbHHR935OUk0tr0hH/Nv0XIIXTz4uXs9PTYD5s=; b=K7chACaYMDaRGExX1A6HHl1xtyW3fyGo3b4d8d7yQX+89xHyZKKYsNXUFRUAJl7ieMHKQQ 9lYnqpAC/gwQ/sUsGNIpFUZZxXBih2tznXkSby/csvimM2HtnoCeDG9Dy8Sf9jixe5XS8Q g3zmzuv1E5IK60R00CA8D1tLLixhhOo= From: Roman Gushchin To: linux-mm@kvack.org, bpf@vger.kernel.org Cc: Suren Baghdasaryan , Johannes Weiner , Michal Hocko , David Rientjes , Matt Bobrowski , Song Liu , Kumar Kartikeya Dwivedi , Alexei Starovoitov , Andrew Morton , linux-kernel@vger.kernel.org, Roman Gushchin Subject: [PATCH v1 09/14] bpf: selftests: introduce read_cgroup_file() helper Date: Mon, 18 Aug 2025 10:01:31 -0700 Message-ID: <20250818170136.209169-10-roman.gushchin@linux.dev> In-Reply-To: <20250818170136.209169-1-roman.gushchin@linux.dev> References: <20250818170136.209169-1-roman.gushchin@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 9926440011 X-Rspam-User: X-Stat-Signature: gg6m8fukgw451c6oiawjx4ccgojiru6g X-Rspamd-Server: rspam09 X-HE-Tag: 1755536542-428870 X-HE-Meta: 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 xliYLri7 dtz1iC2e1Z701f87ZVEAu9y5SkxP08P8QOv1KmGnLjI6XQG9EbbO+FOZzXHi0x9SA0uHdu6mR39GSc53eKefeCYnTdlxujQ8q0k8OhS6Ri8zz3OqeZQGZ9MD3mFssg/obJvvclCb9WD/0iDISGUFobYmN3mmbLS2CDyWZp6n6zHMJ1YKjqDDLtd7hsmMggbU9d4C4ELJmQ7WQeFUz2yS+FF9iEIYCPmuoJk+3K6eU2sz9yRBGbsf3KdtGew== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Implement read_cgroup_file() helper to read from cgroup control files, e.g. statistics. Signed-off-by: Roman Gushchin --- tools/testing/selftests/bpf/cgroup_helpers.c | 39 ++++++++++++++++++++ tools/testing/selftests/bpf/cgroup_helpers.h | 2 + 2 files changed, 41 insertions(+) diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c index e4535451322e..3ffd4b764f91 100644 --- a/tools/testing/selftests/bpf/cgroup_helpers.c +++ b/tools/testing/selftests/bpf/cgroup_helpers.c @@ -125,6 +125,45 @@ int enable_controllers(const char *relative_path, const char *controllers) return __enable_controllers(cgroup_path, controllers); } +static size_t __read_cgroup_file(const char *cgroup_path, const char *file, + char *buf, size_t size) +{ + char file_path[PATH_MAX + 1]; + size_t ret; + int fd; + + snprintf(file_path, sizeof(file_path), "%s/%s", cgroup_path, file); + fd = open(file_path, O_RDONLY); + if (fd < 0) { + log_err("Opening %s", file_path); + return -1; + } + + ret = read(fd, buf, size); + close(fd); + return ret; +} + +/** + * read_cgroup_file() - Read to a cgroup file + * @relative_path: The cgroup path, relative to the workdir + * @file: The name of the file in cgroupfs to read to + * @buf: Buffer to read from the file + * @size: Size of the buffer + * + * Read to a file in the given cgroup's directory. + * + * If successful, the number of read bytes is returned. + */ +size_t read_cgroup_file(const char *relative_path, const char *file, + char *buf, size_t size) +{ + char cgroup_path[PATH_MAX - 24]; + + format_cgroup_path(cgroup_path, relative_path); + return __read_cgroup_file(cgroup_path, file, buf, size); +} + static int __write_cgroup_file(const char *cgroup_path, const char *file, const char *buf) { diff --git a/tools/testing/selftests/bpf/cgroup_helpers.h b/tools/testing/selftests/bpf/cgroup_helpers.h index 502845160d88..821cb76db1f7 100644 --- a/tools/testing/selftests/bpf/cgroup_helpers.h +++ b/tools/testing/selftests/bpf/cgroup_helpers.h @@ -11,6 +11,8 @@ /* cgroupv2 related */ int enable_controllers(const char *relative_path, const char *controllers); +size_t read_cgroup_file(const char *relative_path, const char *file, + char *buf, size_t size); int write_cgroup_file(const char *relative_path, const char *file, const char *buf); int write_cgroup_file_parent(const char *relative_path, const char *file, -- 2.50.1