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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 D6160C3279B for ; Sun, 8 Jul 2018 20:56:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CACD208AF for ; Sun, 8 Jul 2018 20:56:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7CACD208AF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.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 S932834AbeGHU4G (ORCPT ); Sun, 8 Jul 2018 16:56:06 -0400 Received: from mga05.intel.com ([192.55.52.43]:32021 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932162AbeGHU4F (ORCPT ); Sun, 8 Jul 2018 16:56:05 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Jul 2018 13:56:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,327,1526367600"; d="scan'208";a="65327802" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.16]) by orsmga003.jf.intel.com with ESMTP; 08 Jul 2018 13:56:05 -0700 Subject: [PATCH 2/4] lib/iov_iter: Document _copy_to_iter_flushcache() From: Dan Williams To: mingo@kernel.org Cc: Andrew Morton , Andy Lutomirski , Borislav Petkov , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Tony Luck , Al Viro , linux-kernel@vger.kernel.org, x86@kernel.org Date: Sun, 08 Jul 2018 13:46:07 -0700 Message-ID: <153108276767.37979.9462477994086841699.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <153108275728.37979.14771120672220174225.stgit@dwillia2-desk3.amr.corp.intel.com> References: <153108275728.37979.14771120672220174225.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-2-gc94f MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add some theory of operation documentation to _copy_to_iter_flushcache(). Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tony Luck Reported-by: Al Viro Signed-off-by: Dan Williams --- lib/iov_iter.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 94fa361be7bb..09fb73ad9d54 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -727,6 +727,20 @@ size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) EXPORT_SYMBOL(_copy_from_iter_nocache); #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE +/** + * _copy_from_iter_flushcache - write destination through cpu cache + * @addr: destination kernel address + * @bytes: total transfer length + * @iter: source iterator + * + * The pmem driver arranges for filesystem-dax to use this facility via + * dax_copy_from_iter() for ensuring that writes to persistent memory + * are flushed through the CPU cache. It is differentiated from + * _copy_from_iter_nocache() in that guarantees all data is flushed for + * all iterator types. The _copy_from_iter_nocache() only attempts to + * bypass the cache for the ITER_IOVEC case, and on some archs may use + * instructions that strand dirty-data in the cache. + */ size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) { char *to = addr;