From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2026EE49AE for ; Wed, 23 Aug 2023 08:09:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233795AbjHWIJk (ORCPT ); Wed, 23 Aug 2023 04:09:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34530 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233769AbjHWIJT (ORCPT ); Wed, 23 Aug 2023 04:09:19 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EE98E73 for ; Wed, 23 Aug 2023 01:08:37 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-58e4d2b7d16so71990167b3.0 for ; Wed, 23 Aug 2023 01:08:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1692778117; x=1693382917; h=to:from:subject:references:mime-version:message-id:in-reply-to:date :from:to:cc:subject:date:message-id:reply-to; bh=YVPNIKRWrRX85pZfkeIbGqGN+aZoz9nclv8JB/Dx+DY=; b=2maq36UDs0VaiEhSZa+HOihekElrL31Y7dnJsQtE8bZUDmRBFN1lR+rsLege7SaQtM RC+t3k9R4dvAeanDR/0eqeLUy6eDraJwzyW3yUHNYpbCCTMH2eT9TDmEWUFZ84/MWwX1 zxFZvceDTzy0qiEKhDlYcDOepm3nzaCNoJ0OuHLlUkGbMiywB8oGzvw/kpFoak+otjCB Bvep9JpQO5Fx9/PtTYdv/CM+sKZ9PFJD4CBCQFBuHIBxTkhj4kZP9ZX970g49ZXXX5x5 rsI1VPoyeDPgF5Un3KGeDxnrvMZFa5KESm5+vHquELPRCYpdNy2zsdpTQcKGzLRX/7Ge 6oLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692778117; x=1693382917; 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=YVPNIKRWrRX85pZfkeIbGqGN+aZoz9nclv8JB/Dx+DY=; b=N2aGf2CcfukLt4LYN7bMXBz3/StR+HQAigJMKbypRWtfc0dtWgLOgjUIxSAuKuej7a pDKPeffcHOSwtdvCKkw7EI3iYFBG0VHzpJ7BKCvhkTdIKBYjgClKW88mKVxyqngKlTsa rleyS0MU6Gx/U/FbrUlAN4QcJ3gk5YguPNimWf++7qAAN1rzfINIZSkCYwrdayd7Zc8l UiV9aS1N3gZ5I7uyAISmYUs5u2NZtZL5GKaPCtn32pNd9n26sf105tiBaqwZWT5avMkp E2MDl4dyOP6Z629MDPv/3iR5pdxtC/sCbOELHOe8MNL/AMOihdMoQv3rOzEPtqm9iLOs zVAw== X-Gm-Message-State: AOJu0YzgCM2/BlZmv7b616YGfVy6jTvjqozVusvZvcB4O1txoVM5IrD7 +OCHNHKbeHWG19h8tYkDPjkxta6CZZ+s X-Google-Smtp-Source: AGHT+IGNtc+vuUpoFkBQPAmSbNQ4ZcXCetCAAcNdD4zTkg2mp9pmA9kBpq8P8G/UaaTc8ofzxTgEMsGtFGHK X-Received: from irogers.svl.corp.google.com ([2620:15c:2a3:200:3971:e84:f508:9a36]) (user=irogers job=sendgmr) by 2002:a05:6902:691:b0:d4e:e2ae:e0c8 with SMTP id i17-20020a056902069100b00d4ee2aee0c8mr146979ybt.1.1692778116848; Wed, 23 Aug 2023 01:08:36 -0700 (PDT) Date: Wed, 23 Aug 2023 01:08:05 -0700 In-Reply-To: <20230823080828.1460376-1-irogers@google.com> Message-Id: <20230823080828.1460376-3-irogers@google.com> Mime-Version: 1.0 References: <20230823080828.1460376-1-irogers@google.com> X-Mailer: git-send-email 2.42.0.rc1.204.g551eb34607-goog Subject: [PATCH v1 02/25] perf pmu: Avoid a path name copy From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , James Clark , Kan Liang , John Garry , Kajol Jain , Jing Zhang , Ravi Bangoria , Rob Herring , Gaosheng Cui , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org Rather than read a base path and append into a 2nd path, read the base path directly into output buffer and append to that. Signed-off-by: Ian Rogers --- tools/perf/util/pmu.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c index a7f05e4dda97..7683c6749d66 100644 --- a/tools/perf/util/pmu.c +++ b/tools/perf/util/pmu.c @@ -1756,17 +1756,19 @@ int perf_pmu__event_source_devices_fd(void) * then pathname will be filled with * "/sys/bus/event_source/devices/cs_etm/format" * - * Return 0 if the sysfs mountpoint couldn't be found or if no - * characters were written. + * Return 0 if the sysfs mountpoint couldn't be found, if no characters were + * written or if the buffer size is exceeded. */ int perf_pmu__pathname_scnprintf(char *buf, size_t size, const char *pmu_name, const char *filename) { - char base_path[PATH_MAX]; + size_t len; - if (!perf_pmu__event_source_devices_scnprintf(base_path, sizeof(base_path))) + len = perf_pmu__event_source_devices_scnprintf(buf, size); + if (!len || (len + strlen(pmu_name) + strlen(filename) + 1) >= size) return 0; - return scnprintf(buf, size, "%s%s/%s", base_path, pmu_name, filename); + + return scnprintf(buf + len, size - len, "%s/%s", pmu_name, filename); } int perf_pmu__pathname_fd(int dirfd, const char *pmu_name, const char *filename, int flags) -- 2.42.0.rc1.204.g551eb34607-goog