From patchwork Tue Oct 23 13:43:45 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Wilck X-Patchwork-Id: 10653229 X-Patchwork-Delegate: christophe.varoqui@free.fr Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6EA3314BD for ; Tue, 23 Oct 2018 13:52:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 61ADF2989C for ; Tue, 23 Oct 2018 13:52:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 55FEC298B7; Tue, 23 Oct 2018 13:52:27 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id E66F32989C for ; Tue, 23 Oct 2018 13:52:26 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B15E430820F1; Tue, 23 Oct 2018 13:52:25 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 71250798D7; Tue, 23 Oct 2018 13:52:25 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 0389918005AC; Tue, 23 Oct 2018 13:52:25 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id w9NDiNZj001073 for ; Tue, 23 Oct 2018 09:44:23 -0400 Received: by smtp.corp.redhat.com (Postfix) id AAE9B5D763; Tue, 23 Oct 2018 13:44:23 +0000 (UTC) Delivered-To: dm-devel@redhat.com Received: from mx1.redhat.com (ext-mx03.extmail.prod.ext.phx2.redhat.com [10.5.110.27]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4CD1D5D6B3; Tue, 23 Oct 2018 13:44:21 +0000 (UTC) Received: from smtp2.provo.novell.com (smtp2.provo.novell.com [137.65.250.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0176081F0F; Tue, 23 Oct 2018 13:44:20 +0000 (UTC) Received: from apollon.suse.de.de (prv-ext-foundry1int.gns.novell.com [137.65.251.240]) by smtp2.provo.novell.com with ESMTP (TLS encrypted); Tue, 23 Oct 2018 07:44:10 -0600 From: Martin Wilck To: Christophe Varoqui , Benjamin Marzinski Date: Tue, 23 Oct 2018 15:43:45 +0200 Message-Id: <20181023134348.17915-2-mwilck@suse.com> In-Reply-To: <20181023134348.17915-1-mwilck@suse.com> References: <20181023134348.17915-1-mwilck@suse.com> MIME-Version: 1.0 X-Greylist: Sender passed SPF test, Sender IP whitelisted by DNSRBL, ACL 216 matched, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 23 Oct 2018 13:44:20 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 23 Oct 2018 13:44:20 +0000 (UTC) for IP:'137.65.250.81' DOMAIN:'smtp2.provo.novell.com' HELO:'smtp2.provo.novell.com' FROM:'mwilck@suse.com' RCPT:'' X-RedHat-Spam-Score: -2.301 (RCVD_IN_DNSWL_MED, SPF_PASS) 137.65.250.81 smtp2.provo.novell.com 137.65.250.81 smtp2.provo.novell.com X-Scanned-By: MIMEDefang 2.78 on 10.5.110.27 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-loop: dm-devel@redhat.com Cc: dm-devel@redhat.com, Martin Wilck Subject: [dm-devel] [PATCH v2 07/10] libmultipath: handle TUR threads that can't be cancelled X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Tue, 23 Oct 2018 13:52:26 +0000 (UTC) X-Virus-Scanned: ClamAV using ClamSMTP When the tur checker code determines that a hanging TUR thread couldn't be cancelled, rather than simply returning, reallocate the checker context and start a new thread. This will leak some memory if the hanging thread never wakes up again, but well, in that highly unlikely case we're leaking threads anyway. Signed-off-by: Martin Wilck Reviewed-by: Benjamin Marzinski --- libmultipath/checkers/tur.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/libmultipath/checkers/tur.c b/libmultipath/checkers/tur.c index 41210892..a6c88eb2 100644 --- a/libmultipath/checkers/tur.c +++ b/libmultipath/checkers/tur.c @@ -349,11 +349,29 @@ int libcheck_check(struct checker * c) } } else { if (uatomic_read(&ct->holders) > 1) { - /* The thread has been cancelled but hasn't - * quit. exit with timeout. */ + /* + * The thread has been cancelled but hasn't quit. + * We have to prevent it from interfering with the new + * thread. We create a new context and leave the old + * one with the stale thread, hoping it will clean up + * eventually. + */ condlog(3, "%d:%d : tur thread not responding", major(ct->devt), minor(ct->devt)); - return PATH_TIMEOUT; + + /* + * libcheck_init will replace c->context. + * It fails only in OOM situations. In this case, return + * PATH_UNCHECKED to avoid prematurely failing the path. + */ + if (libcheck_init(c) != 0) + return PATH_UNCHECKED; + + if (!uatomic_sub_return(&ct->holders, 1)) + /* It did terminate, eventually */ + cleanup_context(ct); + + ct = c->context; } /* Start new TUR checker */ pthread_mutex_lock(&ct->lock);