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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 431DCC04EB9 for ; Mon, 3 Dec 2018 08:11:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0ACD02082F for ; Mon, 3 Dec 2018 08:11:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0ACD02082F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725870AbeLCILE (ORCPT ); Mon, 3 Dec 2018 03:11:04 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:43978 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725830AbeLCILD (ORCPT ); Mon, 3 Dec 2018 03:11:03 -0500 X-Greylist: delayed 458 seconds by postgrey-1.27 at vger.kernel.org; Mon, 03 Dec 2018 03:11:03 EST Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 49AC787A84; Mon, 3 Dec 2018 08:03:22 +0000 (UTC) Received: from master.localdomain.com (unknown [10.64.242.98]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0C7D02166BA2; Mon, 3 Dec 2018 08:03:20 +0000 (UTC) From: Masatake YAMATO To: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, yamato@redhat.com Subject: [PATCH resend] eventfd: make eventfd files distinguishable in /proc/$PID/fd Date: Mon, 3 Dec 2018 17:03:17 +0900 Message-Id: <20181203080317.1028-1-yamato@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Mon, 03 Dec 2018 08:03:22 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Mon, 03 Dec 2018 08:03:22 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'yamato@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Finding endpoints of an IPC channel is one of essential task to understand how a user program works. Procfs and netlink socket provide enough hints to find endpoints for IPC channels like pipes, unix sockets, and pseudo terminals. However, there is no simple way to find endpoints for an eventfd file from userland. An inode number doesn't hint. Unlike pipe, all eventfd files shares one inode object. To provide the way to find endpoints of an eventfd file, this patch adds eventfd identifiers to the output of 'ls -l /proc/$pid/fd' like: ... lrwx------. 1 qemu qemu 64 May 20 04:49 93 -> 'anon_inode:[eventfd:130]' lrwx------. 1 qemu qemu 64 May 20 04:49 94 -> 'anon_inode:[eventfd:131]' ... Here "130" and "131" are added as identifiers newly added. In the case that ida_simple_get returns an error, this change doesn't add an identifier; just use "[eventfd]" as before. Signed-off-by: Masatake YAMATO --- fs/eventfd.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/eventfd.c b/fs/eventfd.c index 08d3bd602f73..c18952948110 100644 --- a/fs/eventfd.c +++ b/fs/eventfd.c @@ -21,6 +21,11 @@ #include #include #include +#include + +/* Worst case buffer size needed for holding an integer. */ +#define ITOA_MAX_LEN 12 +DEFINE_IDA(eventfd_ida); struct eventfd_ctx { struct kref kref; @@ -35,6 +40,7 @@ struct eventfd_ctx { */ __u64 count; unsigned int flags; + int id; }; /** @@ -69,6 +75,8 @@ EXPORT_SYMBOL_GPL(eventfd_signal); static void eventfd_free_ctx(struct eventfd_ctx *ctx) { + if (ctx->id >= 0) + ida_simple_remove(&eventfd_ida, ctx->id); kfree(ctx); } @@ -384,6 +392,7 @@ static int do_eventfd(unsigned int count, int flags) { struct eventfd_ctx *ctx; int fd; + char name[1 + 8 + ITOA_MAX_LEN + 1 + 1] = "[eventfd]"; /* Check the EFD_* constants for consistency. */ BUILD_BUG_ON(EFD_CLOEXEC != O_CLOEXEC); @@ -400,8 +409,11 @@ static int do_eventfd(unsigned int count, int flags) init_waitqueue_head(&ctx->wqh); ctx->count = count; ctx->flags = flags; + ctx->id = ida_simple_get(&eventfd_ida, 0, 0, GFP_KERNEL); - fd = anon_inode_getfd("[eventfd]", &eventfd_fops, ctx, + if (ctx->id >= 0) + snprintf(name, sizeof(name), "[eventfd:%d]", ctx->id); + fd = anon_inode_getfd(name, &eventfd_fops, ctx, O_RDWR | (flags & EFD_SHARED_FCNTL_FLAGS)); if (fd < 0) eventfd_free_ctx(ctx); -- 2.17.0