From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="COmBgx4L" Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF6D512C for ; Mon, 27 Nov 2023 14:09:32 -0800 (PST) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5cb92becbf6so71001307b3.2 for ; Mon, 27 Nov 2023 14:09:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1701122972; x=1701727772; darn=vger.kernel.org; h=to:from:subject:references:mime-version:message-id:in-reply-to:date :from:to:cc:subject:date:message-id:reply-to; bh=ujtQ3QhQpwDoNxv/mBiBRV+6eibZuimyXiHKFflebSQ=; b=COmBgx4L1//l84yqThO705JA0rnfhKDL7zGmyRiscQFiJ8m1D2SSwPk4sAaUUMvmTg 80yYZQ8UEmRQjs7qeURMKM5phtmMkOF8smhRPOaKSdtwjrmHXNuvWNyg1A/JcrpQUkHz BZZydtTZ+jmUEHm2/dNE3v2ovnfCD972cm2w+yQrrTM45qO1DlKSF5R8K/vUn7g094r0 5ZrgHetW1dEjIHlPjT9TxpKQPx65u1ebrAUpzsszB0gxzVdP2nA3Lva4sRZyd1stXWv9 UajzHr0cAB1lMbHqK63cs6NeCyjOJbryjQ35cioSjPuwu6tc1BBTzXOOC1H4051lteww mapQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701122972; x=1701727772; h=to:from:subject:references:mime-version:message-id:in-reply-to:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ujtQ3QhQpwDoNxv/mBiBRV+6eibZuimyXiHKFflebSQ=; b=MXnEkXfu3sZvmO2neYgGa/MsgjC7cD7XeG3Nx85zKHA5l56nR/087e87Bn6LQX/ttg aRRTKgDUvphNav4ihH1aiExkzQ2mPRSHJj2vhuSHkhEJNPcXw+U3aN+aFtJK05uQVhl5 4lyQkQwW1djrmnQV2Ok5Tt6AXM/c01OKUBBYMP1GH3jN1nY9RuQA7pPMEV85fJ7Ld6TN NTfGC+wI6H50M7DhPiI3sA1jmxVr5xwRbv+BcyKaQDU7klWuO69/wmcHLbwlfUBP28zm mtaRRDLdTnIeoZaZDkJstme3q54sAJ7Nv3ttaqRLevrTWbjyuUrrys10oOEehr/yzVpp 4GYQ== X-Gm-Message-State: AOJu0YxK5AeEfQkuebXgv0EWzYJd9h/setSgSyaSGuw6eTXKRy0BEaWQ yfBDThwRX0yEPBIChLDP7q3BbHCllFL+ X-Google-Smtp-Source: AGHT+IE15NVm0P2tzub/k7bVxns1jsuHZLV+W+ubNfzDivu1+mCTMHwctkrWJwb3d1cSHMdlaehOprszJXNj X-Received: from irogers.svl.corp.google.com ([2620:15c:2a3:200:829:6e77:9093:f39b]) (user=irogers job=sendgmr) by 2002:a05:690c:3105:b0:5cc:4276:1c6b with SMTP id fb5-20020a05690c310500b005cc42761c6bmr362765ywb.4.1701122972182; Mon, 27 Nov 2023 14:09:32 -0800 (PST) Date: Mon, 27 Nov 2023 14:08:17 -0800 In-Reply-To: <20231127220902.1315692-1-irogers@google.com> Message-Id: <20231127220902.1315692-6-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20231127220902.1315692-1-irogers@google.com> X-Mailer: git-send-email 2.43.0.rc1.413.gea7ed67945-goog Subject: [PATCH v5 05/50] tools api fs: Avoid reading whole file for a 1 byte bool From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Nick Terrell , Kan Liang , Andi Kleen , Kajol Jain , Athira Rajeev , Huacai Chen , Masami Hiramatsu , Vincent Whitchurch , "Steinar H. Gunderson" , Liam Howlett , Miguel Ojeda , Colin Ian King , Dmitrii Dolgov <9erthalion6@gmail.com>, Yang Jihong , Ming Wang , James Clark , K Prateek Nayak , Sean Christopherson , Leo Yan , Ravi Bangoria , German Gomez , Changbin Du , Paolo Bonzini , Li Dong , Sandipan Das , liuwenyu , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Guilherme Amadio Content-Type: text/plain; charset="UTF-8" sysfs__read_bool used the first byte from a fully read file into a string. It then looked at the first byte's value. Avoid doing this and just read the first byte. Signed-off-by: Ian Rogers --- tools/lib/api/fs/fs.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c index 004f2af5504b..337fde770e45 100644 --- a/tools/lib/api/fs/fs.c +++ b/tools/lib/api/fs/fs.c @@ -447,15 +447,22 @@ int sysfs__read_str(const char *entry, char **buf, size_t *sizep) int sysfs__read_bool(const char *entry, bool *value) { - char *buf; - size_t size; - int ret; + struct io io; + char bf[16]; + int ret = 0; + char path[PATH_MAX]; + const char *sysfs = sysfs__mountpoint(); + + if (!sysfs) + return -1; - ret = sysfs__read_str(entry, &buf, &size); - if (ret < 0) - return ret; + snprintf(path, sizeof(path), "%s/%s", sysfs, entry); + io.fd = open(path, O_RDONLY); + if (io.fd < 0) + return -errno; - switch (buf[0]) { + io__init(&io, io.fd, bf, sizeof(bf)); + switch (io__get_char(&io)) { case '1': case 'y': case 'Y': @@ -469,8 +476,7 @@ int sysfs__read_bool(const char *entry, bool *value) default: ret = -1; } - - free(buf); + close(io.fd); return ret; } -- 2.43.0.rc1.413.gea7ed67945-goog