From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965780AbeBMUpw (ORCPT ); Tue, 13 Feb 2018 15:45:52 -0500 Received: from mga11.intel.com ([192.55.52.93]:42960 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965719AbeBMUpv (ORCPT ); Tue, 13 Feb 2018 15:45:51 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,509,1511856000"; d="scan'208";a="203851891" Subject: Re: [PATCH] lib/scatterlist: Make sg_page_count() accessible to other modules To: Andy Shevchenko Cc: chris@chris-wilson.co.uk, Linux Kernel Mailing List References: <1518285964-31657-1-git-send-email-alexey.skidanov@intel.com> From: Alexey Skidanov Message-ID: Date: Tue, 13 Feb 2018 22:46:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/13/2018 10:14 PM, Andy Shevchenko wrote: > On Sat, Feb 10, 2018 at 8:06 PM, Alexey Skidanov > wrote: >> Currently, sg_page_count() may be used only inside the scatterlist.c file. >> >> However, the same calculation is done outside of scatterlist.c file >> causing to code duplication. >> >> To fix this, we move the sg_page_count() to the scatterlist.h file, making it >> accessible to other modules. > > Can you provide an example of potential (or existing?) use case? > This one, for example - drivers/staging/android/ion/ion_heap.c: for_each_sg(table->sgl, sg, table->nents, i) { int npages_this_entry = PAGE_ALIGN(sg->length) / PAGE_SIZE; struct page *page = sg_page(sg); BUG_ON(i >= npages); for (j = 0; j < npages_this_entry; j++) *(tmp++) = page++; } One more is in the patch I have submitted for review. >> >> Signed-off-by: Alexey Skidanov >> --- >> include/linux/scatterlist.h | 5 +++++ >> lib/scatterlist.c | 5 ----- >> 2 files changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h >> index b7c8325..fe28148 100644 >> --- a/include/linux/scatterlist.h >> +++ b/include/linux/scatterlist.h >> @@ -248,6 +248,11 @@ static inline void *sg_virt(struct scatterlist *sg) >> return page_address(sg_page(sg)) + sg->offset; >> } >> >> +static inline int sg_page_count(struct scatterlist *sg) >> +{ >> + return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; >> +} >> + >> int sg_nents(struct scatterlist *sg); >> int sg_nents_for_len(struct scatterlist *sg, u64 len); >> struct scatterlist *sg_next(struct scatterlist *); >> diff --git a/lib/scatterlist.c b/lib/scatterlist.c >> index 7c1c55f..4a59131 100644 >> --- a/lib/scatterlist.c >> +++ b/lib/scatterlist.c >> @@ -486,11 +486,6 @@ void __sg_page_iter_start(struct sg_page_iter *piter, >> } >> EXPORT_SYMBOL(__sg_page_iter_start); >> >> -static int sg_page_count(struct scatterlist *sg) >> -{ >> - return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; >> -} >> - >> bool __sg_page_iter_next(struct sg_page_iter *piter) >> { >> if (!piter->__nents || !piter->sg) >> -- >> 2.7.4 >> > > >