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 X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01F90C433E0 for ; Fri, 15 Jan 2021 13:05:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1D65221FA for ; Fri, 15 Jan 2021 13:04:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387471AbhAONEk (ORCPT ); Fri, 15 Jan 2021 08:04:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387742AbhAONE2 (ORCPT ); Fri, 15 Jan 2021 08:04:28 -0500 Received: from mail-wm1-x34a.google.com (mail-wm1-x34a.google.com [IPv6:2a00:1450:4864:20::34a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 53B46C061794 for ; Fri, 15 Jan 2021 05:03:48 -0800 (PST) Received: by mail-wm1-x34a.google.com with SMTP id g82so2961236wmg.6 for ; Fri, 15 Jan 2021 05:03:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=jOOfDKQx1+jPnbv33agbvLGtXZ2MbhOFvMWdPLPRW0k=; b=Dlq9uaH+pIB75P7MKmxH+aUEe4eGD10sBNXqDWp/qunB8HR5dcReV4Z2eIviWjc/P6 Vt9jvadWbhJp0D/aZyhiP5wGE9wQUsQOTnCiPaeWNPQtfFPRCz03VlSdmi7ysHZYwIZI 5Xl/6HCkGZ4QSXNEmK3ER8XR4fdzYRouvHBhg/CCMlMVhbhHGQ8OiXqSWNCNhiWDwY44 tgRMA4O3D/h+Kl1w9S9GWC/D0XgVxFyq3CcgG+q4XB7UdyoFR1t7RCDatIifBKIzb2vg m8QhBN3U2fPqoxqC4zcLDc26MpSEyLwLG/ezS0R+ihp/jH0mtIbqNBEKqNPZiYOjtcKL RM8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=jOOfDKQx1+jPnbv33agbvLGtXZ2MbhOFvMWdPLPRW0k=; b=T809UibTB0r1pul1YuRPZs3nUIgVWRAEbAw4cEXAMr0Ea8ST9ONI1uOewRQgUvJikw junhZ8MHo1hOcWd75lQFQCqNxvANjK3E6SKWT1mHH/f28iW4DDA8l3IjcaNyzrYPrzn9 HjX9cdZYWRZUZK/f5K3s+PGDDXY+Z6KSU8eyAT1BdlD1O4KbDSR+XFfW8SLO5U2VeCgE 3Xqcv0vLIhXbWbqRzhRS6cfFpJHPivyTotIIQecLxEUekaNyjJIRYfeyhwo+NDO5RZTR FSXQBVdUvOidI39XCjEoep1Kbh8zACCPDA575SmJIcutfeY1U738pmJOHRq0LU87tNDj O9kw== X-Gm-Message-State: AOAM5324PGW+EGjqSLAjS+mZvvj/nQyGcSKX0RCVsib1A0PZEVF/WCAC BfnDejoEERDm26i0LonQQ4tNY02iHsGkPEi3gZtHzTdGtlUEmZAorakt9OwL5or6pIa8Jv6EVSM 7KTyzvrmAG55ZjGO0+gRLALUoXbCGGCRoHJF7IRLbR3YQLwOQ74mzv/iqLIX7ppILkuzaWQ== X-Google-Smtp-Source: ABdhPJxlZI7UXjDHh8f5aiGTii0hBsMm1kPklYbJotEJlDg6aIGyTVeSV+JktC6XgXB8pT4mP8GUISHL+JI= Sender: "glider via sendgmr" X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:f693:9fff:fef4:9ff]) (user=glider job=sendgmr) by 2002:a1c:2c89:: with SMTP id s131mr934933wms.0.1610715826432; Fri, 15 Jan 2021 05:03:46 -0800 (PST) Date: Fri, 15 Jan 2021 14:03:34 +0100 In-Reply-To: <20210115130336.2520663-1-glider@google.com> Message-Id: <20210115130336.2520663-4-glider@google.com> Mime-Version: 1.0 References: <20210115130336.2520663-1-glider@google.com> X-Mailer: git-send-email 2.30.0.284.gd98b1dd5eaa7-goog Subject: [PATCH v2 3/5] docs: ABI: add /sys/kernel/error_report/ documentation From: Alexander Potapenko To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: andreyknvl@google.com, dvyukov@google.com, mingo@redhat.com, elver@google.com, pmladek@suse.com, rostedt@goodmis.org, sergey.senozhatsky@gmail.com, glider@google.com, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add ABI documentation for files in /sys/kernel/error_report/ Requested-by: Andrew Morton Cc: Andrew Morton Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Ingo Molnar Cc: Marco Elver Cc: Petr Mladek Cc: Steven Rostedt Cc: Sergey Senozhatsky Cc: linux-mm@kvack.org Signed-off-by: Alexander Potapenko --- .../ABI/testing/sysfs-kernel-error_report | 41 +++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-error_report diff --git a/Documentation/ABI/testing/sysfs-kernel-error_report b/Documentation/ABI/testing/sysfs-kernel-error_report new file mode 100644 index 000000000000..666d039f93a9 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-error_report @@ -0,0 +1,41 @@ +What: /sys/kernel/error_report/ +Date: January 2021 +Contact: Alexander Potapenko , + Marco Elver +Description: + /sys/kernel/error_report/ contains two files: "report_count" + and "last_report". These files are used to notify userspace + about error reports from the enrolled kernel subsystems (those + that use error_report_start/error_report_end tracepoints). + + "report_count" contains the current number of reported errors. + This number is incremented every time the error_report_end + trace event occurs in the kernel. + + "last_report" contains the most recent error report; concurrent + report generation results in collection of any one report + ("last_report" may not be the last shown on the console). + A "report" is everything the task had printed to the console + between issuing the error_report_start and error_report_end + trace events. + + Due to sysfs limitations, the report size is truncated at + PAGE_SIZE. To save space, the leading info in square brackets + printed by CONFIG_PRINTK_TIME and CONFIG_PRINTK_CALLER is + trimmed from the output lines. + + Both files use sysfs_notify() to notify userspace about + changes. Userspace programs can use poll() to block until an + error is reported: + + pfd.fd = fd; + pfd.events = POLLPRI; + while (1) { + lseek(pfd.fd, 0, SEEK_SET); + poll(&pfd, 1, -1); + read(pfd.fd, buffer, PAGE_SIZE); + /* Process the report in @buffer. */ + } + + Files in /sys/kernel/error_report/ are available when + CONFIG_ERROR_REPORT_NOTIFY is enabled. -- 2.30.0.284.gd98b1dd5eaa7-goog