From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936506AbZDJMem (ORCPT ); Fri, 10 Apr 2009 08:34:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756796AbZDJMe1 (ORCPT ); Fri, 10 Apr 2009 08:34:27 -0400 Received: from hera.kernel.org ([140.211.167.34]:41633 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763304AbZDJMeY (ORCPT ); Fri, 10 Apr 2009 08:34:24 -0400 Date: Fri, 10 Apr 2009 12:33:46 GMT From: Andy Grover To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, andy.grover@oracle.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, andy.grover@oracle.com, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <1239320729-3262-1-git-send-email-andy.grover@oracle.com> References: <1239320729-3262-1-git-send-email-andy.grover@oracle.com> Subject: [tip:x86/pat] x86: Document get_user_pages_fast() Message-ID: Git-Commit-ID: a0d22f485af1553060b4094ee0154537a8f6a8a6 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Fri, 10 Apr 2009 12:33:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: a0d22f485af1553060b4094ee0154537a8f6a8a6 Gitweb: http://git.kernel.org/tip/a0d22f485af1553060b4094ee0154537a8f6a8a6 Author: Andy Grover AuthorDate: Thu, 9 Apr 2009 16:45:29 -0700 Committer: Ingo Molnar CommitDate: Fri, 10 Apr 2009 13:14:08 +0200 x86: Document get_user_pages_fast() 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 Cc: npiggin@suse.de Cc: akpm@linux-foundation.org LKML-Reference: <1239320729-3262-1-git-send-email-andy.grover@oracle.com> Signed-off-by: Ingo Molnar --- 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) {