From owner-svn-src-all@freebsd.org Mon Sep 2 17:10:47 2019 Return-Path: Delivered-To: svn-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 070C7E33D1; Mon, 2 Sep 2019 17:10:47 +0000 (UTC) (envelope-from imp@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46Mc6Z6FM9z42P3; Mon, 2 Sep 2019 17:10:46 +0000 (UTC) (envelope-from imp@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id B980E1D464; Mon, 2 Sep 2019 17:10:46 +0000 (UTC) (envelope-from imp@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x82HAkNG095243; Mon, 2 Sep 2019 17:10:46 GMT (envelope-from imp@FreeBSD.org) Received: (from imp@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x82HAkTe095242; Mon, 2 Sep 2019 17:10:46 GMT (envelope-from imp@FreeBSD.org) Message-Id: <201909021710.x82HAkTe095242@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: imp set sender to imp@FreeBSD.org using -f From: Warner Losh Date: Mon, 2 Sep 2019 17:10:46 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r351704 - head/sys/dev/nvme X-SVN-Group: head X-SVN-Commit-Author: imp X-SVN-Commit-Paths: head/sys/dev/nvme X-SVN-Commit-Revision: 351704 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 02 Sep 2019 17:10:47 -0000 Author: imp Date: Mon Sep 2 17:10:46 2019 New Revision: 351704 URL: https://svnweb.freebsd.org/changeset/base/351704 Log: Add a brief comment explaining why we can return ETIMEDOUT from the call to the polled interface. Normally this would have the potential to corrupt stack memory because the completion routines would run after we return. In this case, however, we're doing a dump so it's safe for reasons explained in the comment. Modified: head/sys/dev/nvme/nvme_ns_cmd.c Modified: head/sys/dev/nvme/nvme_ns_cmd.c ============================================================================== --- head/sys/dev/nvme/nvme_ns_cmd.c Mon Sep 2 16:57:42 2019 (r351703) +++ head/sys/dev/nvme/nvme_ns_cmd.c Mon Sep 2 17:10:46 2019 (r351704) @@ -191,6 +191,14 @@ nvme_ns_dump(struct nvme_namespace *ns, void *virt, of nvme_qpair_process_completions(req->qpair); } + /* + * Normally, when using the polling interface, we can't return a + * timeout error because we don't know when the completion routines + * will be called if the command later completes. However, in this + * case we're running a system dump, so all interrupts are turned + * off, the scheduler isn't running so there's nothing to complete + * the transaction. + */ if (status.done == FALSE) return (ETIMEDOUT);