From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935816AbZDIXqv (ORCPT ); Thu, 9 Apr 2009 19:46:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759572AbZDIXqm (ORCPT ); Thu, 9 Apr 2009 19:46:42 -0400 Received: from acsinet11.oracle.com ([141.146.126.233]:31294 "EHLO acsinet11.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757432AbZDIXql (ORCPT ); Thu, 9 Apr 2009 19:46:41 -0400 From: Andy Grover To: linux-kernel@vger.kernel.org Cc: mingo@redhat.com, npiggin@suse.de, akpm@linux-foundation.org Subject: [PATCH 1/1] x86: Document get_user_pages_fast() Date: Thu, 9 Apr 2009 16:45:29 -0700 Message-Id: <1239320729-3262-1-git-send-email-andy.grover@oracle.com> X-Mailer: git-send-email 1.5.6.3 X-Source-IP: acsmt701.oracle.com [141.146.40.71] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A010201.49DE88A0.01D1:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While better than get_user_pages(), the usage of gupf(), especially the return values and the fact that it can potentially only partially pin the range, warranted some documentation. Signed-off-by: Andy Grover --- arch/x86/mm/gup.c | 16 ++++++++++++++++ 1 files changed, 16 insertions(+), 0 deletions(-) diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index be54176..6340cef 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -219,6 +219,22 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end, return 1; } +/** + * get_user_pages_fast() - pin user pages in memory + * @start: starting user address + * @nr_pages: number of pages from start to pin + * @write: whether pages will be written to + * @pages: array that receives pointers to the pages pinned. + * Should be at least nr_pages long. + * + * Attempt to pin user pages in memory without taking mm->mmap_sem. + * If not successful, it will fall back to taking the lock and + * calling get_user_pages(). + * + * Returns number of pages pinned. This may be fewer than the number + * requested. If nr_pages is 0 or negative, returns 0. If no pages + * were pinned, returns -errno. + */ int get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) { -- 1.5.6.3