From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937595AbZDJAqb (ORCPT ); Thu, 9 Apr 2009 20:46:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755034AbZDJAqW (ORCPT ); Thu, 9 Apr 2009 20:46:22 -0400 Received: from acsinet12.oracle.com ([141.146.126.234]:45217 "EHLO acsinet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754235AbZDJAqV (ORCPT ); Thu, 9 Apr 2009 20:46:21 -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] Document get_user_pages_fast() Date: Thu, 9 Apr 2009 17:44:43 -0700 Message-Id: <1239324283-4279-1-git-send-email-andy.grover@oracle.com> X-Mailer: git-send-email 1.5.6.3 X-Source-IP: acsmt700.oracle.com [141.146.40.70] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090206.49DE9683.019B: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 --- mm/util.c | 16 ++++++++++++++++ 1 files changed, 16 insertions(+), 0 deletions(-) diff --git a/mm/util.c b/mm/util.c index 2599e83..55bef16 100644 --- a/mm/util.c +++ b/mm/util.c @@ -223,6 +223,22 @@ void arch_pick_mmap_layout(struct mm_struct *mm) } #endif +/** + * 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 __attribute__((weak)) get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) { -- 1.5.6.3