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GET /api/patches/810723/?format=api
{ "id": 810723, "url": "http://patchwork.ozlabs.org/api/patches/810723/?format=api", "web_url": "http://patchwork.ozlabs.org/project/netdev/patch/20170906163551.20387-1-Haakon.Bugge@oracle.com/", "project": { "id": 7, "url": "http://patchwork.ozlabs.org/api/projects/7/?format=api", "name": "Linux network development", "link_name": "netdev", "list_id": "netdev.vger.kernel.org", "list_email": "netdev@vger.kernel.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20170906163551.20387-1-Haakon.Bugge@oracle.com>", "list_archive_url": null, "date": "2017-09-06T16:35:51", "name": "[net,v2] rds: Fix incorrect statistics counting", "commit_ref": null, "pull_url": null, "state": "accepted", "archived": true, "hash": "bd6a5949c1403c96d30b655661e327b5a382fdb3", "submitter": { "id": 72009, "url": "http://patchwork.ozlabs.org/api/people/72009/?format=api", "name": "Haakon Bugge", "email": "Haakon.Bugge@oracle.com" }, "delegate": { "id": 34, "url": "http://patchwork.ozlabs.org/api/users/34/?format=api", "username": "davem", "first_name": "David", "last_name": "Miller", "email": "davem@davemloft.net" }, "mbox": "http://patchwork.ozlabs.org/project/netdev/patch/20170906163551.20387-1-Haakon.Bugge@oracle.com/mbox/", "series": [ { "id": 1850, "url": "http://patchwork.ozlabs.org/api/series/1850/?format=api", "web_url": "http://patchwork.ozlabs.org/project/netdev/list/?series=1850", "date": "2017-09-06T16:35:51", "name": "[net,v2] rds: Fix incorrect statistics counting", "version": 2, "mbox": "http://patchwork.ozlabs.org/series/1850/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/810723/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/810723/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<netdev-owner@vger.kernel.org>", "X-Original-To": "patchwork-incoming@ozlabs.org", "Delivered-To": "patchwork-incoming@ozlabs.org", "Authentication-Results": "ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=netdev-owner@vger.kernel.org;\n\treceiver=<UNKNOWN>)", "Received": [ "from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3xnTks46bNz9t2R\n\tfor <patchwork-incoming@ozlabs.org>;\n\tThu, 7 Sep 2017 02:37:09 +1000 (AEST)", "(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1755471AbdIFQgo (ORCPT <rfc822;patchwork-incoming@ozlabs.org>);\n\tWed, 6 Sep 2017 12:36:44 -0400", "from aserp1040.oracle.com ([141.146.126.69]:34630 \"EHLO\n\taserp1040.oracle.com\" rhost-flags-OK-OK-OK-OK) by vger.kernel.org\n\twith ESMTP id S1753775AbdIFQgm (ORCPT\n\t<rfc822;netdev@vger.kernel.org>); Wed, 6 Sep 2017 12:36:42 -0400", "from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74])\n\tby aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with\n\tESMTP id v86Ga4Ka002281\n\t(version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256\n\tverify=OK); Wed, 6 Sep 2017 16:36:05 GMT", "from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75])\n\tby userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id v86Ga3VX023269\n\t(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256\n\tverify=OK); Wed, 6 Sep 2017 16:36:03 GMT", "from abhmp0011.oracle.com (abhmp0011.oracle.com [141.146.116.17])\n\tby userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id\n\tv86Ga3f0013258; Wed, 6 Sep 2017 16:36:03 GMT", "from lab02.no.oracle.com (/10.172.144.56)\n\tby default (Oracle Beehive Gateway v4.0)\n\twith ESMTP ; Wed, 06 Sep 2017 09:36:02 -0700" ], "From": "=?utf-8?q?H=C3=A5kon_Bugge?= <Haakon.Bugge@oracle.com>", "To": "Santosh Shilimkar <santosh.shilimkar@oracle.com>,\n\t\"David S . Miller\" <davem@davemloft.net>", "Cc": "netdev@vger.kernel.org, linux-rdma@vger.kernel.org,\n\trds-devel@oss.oracle.com, linux-kernel@vger.kernel.org,\n\tknut.omang@oracle.com", "Subject": "[PATCH net v2] rds: Fix incorrect statistics counting", "Date": "Wed, 6 Sep 2017 18:35:51 +0200", "Message-Id": "<20170906163551.20387-1-Haakon.Bugge@oracle.com>", "X-Mailer": "git-send-email 2.9.3", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=UTF-8", "Content-Transfer-Encoding": "8bit", "X-Source-IP": "userv0022.oracle.com [156.151.31.74]", "Sender": "netdev-owner@vger.kernel.org", "Precedence": "bulk", "List-ID": "<netdev.vger.kernel.org>", "X-Mailing-List": "netdev@vger.kernel.org" }, "content": "In rds_send_xmit() there is logic to batch the sends. However, if\nanother thread has acquired the lock and has incremented the send_gen,\nit is considered a race and we yield. The code incrementing the\ns_send_lock_queue_raced statistics counter did not count this event\ncorrectly.\n\nThis commit counts the race condition correctly.\n\nChanges from v1:\n- Removed check for *someone_on_xmit()*\n- Fixed incorrect indentation\n\nSigned-off-by: Håkon Bugge <haakon.bugge@oracle.com>\nReviewed-by: Knut Omang <knut.omang@oracle.com>\n---\n net/rds/send.c | 10 +++++++---\n 1 file changed, 7 insertions(+), 3 deletions(-)", "diff": "diff --git a/net/rds/send.c b/net/rds/send.c\nindex 058a407..b52cdc8 100644\n--- a/net/rds/send.c\n+++ b/net/rds/send.c\n@@ -428,14 +428,18 @@ int rds_send_xmit(struct rds_conn_path *cp)\n \t * some work and we will skip our goto\n \t */\n \tif (ret == 0) {\n+\t\tbool raced;\n+\n \t\tsmp_mb();\n+\t\traced = send_gen != READ_ONCE(cp->cp_send_gen);\n+\n \t\tif ((test_bit(0, &conn->c_map_queued) ||\n-\t\t !list_empty(&cp->cp_send_queue)) &&\n-\t\t\tsend_gen == READ_ONCE(cp->cp_send_gen)) {\n-\t\t\trds_stats_inc(s_send_lock_queue_raced);\n+\t\t !list_empty(&cp->cp_send_queue)) && !raced) {\n \t\t\tif (batch_count < send_batch_count)\n \t\t\t\tgoto restart;\n \t\t\tqueue_delayed_work(rds_wq, &cp->cp_send_w, 1);\n+\t\t} else if (raced) {\n+\t\t\trds_stats_inc(s_send_lock_queue_raced);\n \t\t}\n \t}\n out:\n", "prefixes": [ "net", "v2" ] }