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 9D922C4332F for ; Mon, 17 Oct 2022 17:55:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230264AbiJQRzd (ORCPT ); Mon, 17 Oct 2022 13:55:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54580 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230333AbiJQRzc (ORCPT ); Mon, 17 Oct 2022 13:55:32 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2CA252470 for ; Mon, 17 Oct 2022 10:55:30 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id c12-20020a170903234c00b0017f695bf8f0so8078919plh.6 for ; Mon, 17 Oct 2022 10:55:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=agT9QZQMe+zYcofiwo2fky7Lo5K5JsV+HiadouuU+xY=; b=S7DlGIdUa4amE9BoDHGwjgJKqiO83psDwvsaprmeCr6GoWIkFEdQbvV1sXIPEdMv9g 0S+OXhabA0N1xRVPgyuPg8TszXx/+yHwEO/CwpGp6XtpFK4Aa0li2Rgx7e8Wep8ZS4Yg D2hoxAMrGZxuAweBsXnXIRb2O4uBtN4Hu9jS5ucQx6yD3+/rFU9BvVSoZ40szyivSNPQ mPYW2ZFLSvD8UW88Br1sKdAu1R5d5pxrbcFyU/efuZkbveR396g+Zsvi7twrPveruTq1 bibaRLQLbg+zlWTHOfH5AEGo01xabCQUJWuWanJovvYb+5EK1z3YP+FGpyatA6wVwCX2 T1wQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=agT9QZQMe+zYcofiwo2fky7Lo5K5JsV+HiadouuU+xY=; b=pI4w2Tw4YfmImix1cpoDjbN6Ok6ozMOQwUZw79EuQSZvvC/+Y2daitOoFVR+lDRJiG pQTDfOe9Q/O5JASV8LSkqx7Ckf9An8a10HhyZUfttwW7colthTr+XJb3wO7fxB/oCo8c dWHAgtbz7E6SEBDsdYhjP7eQN6WqDnVKCS73eZqMyeSI41CEehql0MPKDe7wn6NuJfpw FXQ4cmwkUHYklXtqWuflAbI3lIMphoX6G5BBJYQq+38MTA6f0H6tvTzmULz4HHl19bVI j6G71tlBTA6nfb4RcDg5XlAbzV8jqriaXhmAn4t2eihu4UD1CwXHTVarLVEaGkLc61hR Qfgg== X-Gm-Message-State: ACrzQf01YhDkxn/o8JTqDtjN8uTRGET1UYpoBP3duKlXQJwn9ANire/b qGgXXxNjflE3fLwbZKpOsk2HFw5KmEZw X-Google-Smtp-Source: AMsMyM5HuNyELUBHl+u6TZZkzRJi+vyJvjs8M4Fo5QyR44pbs2aljP0dCpBB03K1dW9Fpcw4ETF6ejUH7NJA X-Received: from zokeefe3.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1b6]) (user=zokeefe job=sendgmr) by 2002:a17:902:ef92:b0:17e:2618:ee91 with SMTP id iz18-20020a170902ef9200b0017e2618ee91mr13497088plb.122.1666029329663; Mon, 17 Oct 2022 10:55:29 -0700 (PDT) Date: Mon, 17 Oct 2022 10:55:21 -0700 In-Reply-To: <20221017175523.2048887-1-zokeefe@google.com> Mime-Version: 1.0 References: <20221017175523.2048887-1-zokeefe@google.com> X-Mailer: git-send-email 2.38.0.413.g74048e4d9e-goog Message-ID: <20221017175523.2048887-3-zokeefe@google.com> Subject: [PATCH man-pages 2/4] madvise.2: document reliable probe for advice support From: Zach OKeefe To: Alejandro Colomar , Michael Kerrisk Cc: Yang Shi , linux-mm@kvack.org, linux-man@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org From: Zach O'Keefe EINVAL is an overloaded error code for madvise(2) and it's not clear under what context it means "advice is not valid" vs another error. Explicitly document that madvise(0, 0, advice) can reliably be used to probe for kernel support for "advice", returning zero iff "advice" is supported by the kernel. Signed-off-by: Zach O'Keefe --- man2/madvise.2 | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/man2/madvise.2 b/man2/madvise.2 index e14e0f7fb..adfe24c24 100644 --- a/man2/madvise.2 +++ b/man2/madvise.2 @@ -789,6 +789,13 @@ that are not mapped, the Linux version of ignores them and applies the call to the rest (but returns .B ENOMEM from the system call, as it should). +.PP +.BR madvise (0, +0, +.IR advice ) +will return zero iff +.I advice +is supported by the kernel and can be relied on to probe for support. .\" .SH HISTORY .\" The .\" .BR madvise () -- 2.38.0.413.g74048e4d9e-goog