From patchwork Mon Mar 7 22:35:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 593377 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id BB708140273; Tue, 8 Mar 2016 09:39:18 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ad3o3-0001VJ-Dl; Mon, 07 Mar 2016 22:39:15 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1ad3k7-0007ag-3g for kernel-team@lists.ubuntu.com; Mon, 07 Mar 2016 22:35:11 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ad3k6-0007Zx-L9; Mon, 07 Mar 2016 22:35:10 +0000 Received: from kamal by fourier with local (Exim 4.86) (envelope-from ) id 1ad3k3-0000OL-Vy; Mon, 07 Mar 2016 14:35:07 -0800 From: Kamal Mostafa To: Ilya Dryomov Subject: [4.2.y-ckt stable] Patch "libceph: don't bail early from try_read() when skipping a message" has been added to the 4.2.y-ckt tree Date: Mon, 7 Mar 2016 14:35:06 -0800 Message-Id: <1457390106-1468-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 X-Extended-Stable: 4.2 Cc: Varada Kari , Kamal Mostafa , kernel-team@lists.ubuntu.com, Alex Elder X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled libceph: don't bail early from try_read() when skipping a message to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt5. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 8627b2f646a9101412f1eac20fa947e3b55a9efa Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Wed, 17 Feb 2016 20:04:08 +0100 Subject: libceph: don't bail early from try_read() when skipping a message commit e7a88e82fe380459b864e05b372638aeacb0f52d upstream. The contract between try_read() and try_write() is that when called each processes as much data as possible. When instructed by osd_client to skip a message, try_read() is violating this contract by returning after receiving and discarding a single message instead of checking for more. try_write() then gets a chance to write out more requests, generating more replies/skips for try_read() to handle, forcing the messenger into a starvation loop. Reported-by: Varada Kari Signed-off-by: Ilya Dryomov Tested-by: Varada Kari Reviewed-by: Alex Elder Signed-off-by: Kamal Mostafa --- net/ceph/messenger.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 2.7.0 diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index ec564c5..1d47fa3 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -2328,7 +2328,7 @@ static int read_partial_message(struct ceph_connection *con) con->in_base_pos = -front_len - middle_len - data_len - sizeof(m->footer); con->in_tag = CEPH_MSGR_TAG_READY; - return 0; + return 1; } else if ((s64)seq - (s64)con->in_seq > 1) { pr_err("read_partial_message bad seq %lld expected %lld\n", seq, con->in_seq + 1); @@ -2361,7 +2361,7 @@ static int read_partial_message(struct ceph_connection *con) sizeof(m->footer); con->in_tag = CEPH_MSGR_TAG_READY; con->in_seq++; - return 0; + return 1; } BUG_ON(!con->in_msg);