From patchwork Tue Nov 19 08:16:21 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11251463 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BF613138C for ; Tue, 19 Nov 2019 08:20:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9339F208C3 for ; Tue, 19 Nov 2019 08:20:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="Vx7w9+w5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728250AbfKSIUT (ORCPT ); Tue, 19 Nov 2019 03:20:19 -0500 Received: from hqemgate16.nvidia.com ([216.228.121.65]:12713 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727472AbfKSIQ7 (ORCPT ); Tue, 19 Nov 2019 03:16:59 -0500 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 19 Nov 2019 00:16:51 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Tue, 19 Nov 2019 00:16:50 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Tue, 19 Nov 2019 00:16:50 -0800 Received: from HQMAIL109.nvidia.com (172.20.187.15) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 19 Nov 2019 08:16:49 +0000 Received: from HQMAIL109.nvidia.com (172.20.187.15) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 19 Nov 2019 08:16:49 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Tue, 19 Nov 2019 08:16:48 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Tue, 19 Nov 2019 00:16:48 -0800 From: John Hubbard To: Andrew Morton CC: Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?utf-8?b?QmrDtnJuIFQ=?= =?utf-8?b?w7ZwZWw=?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Magnus Karlsson , "Mauro Carvalho Chehab" , Michael Ellerman , Michal Hocko , Mike Kravetz , "Paul Mackerras" , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML , John Hubbard , "Christoph Hellwig" , "Aneesh Kumar K . V" Subject: [PATCH v6 02/24] mm/gup: factor out duplicate code from four routines Date: Tue, 19 Nov 2019 00:16:21 -0800 Message-ID: <20191119081643.1866232-3-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191119081643.1866232-1-jhubbard@nvidia.com> References: <20191119081643.1866232-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1574151411; bh=AJB77Rx4Grn5/pvcGhctYUQNnGXjamViAFqO5obaUFI=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Type:Content-Transfer-Encoding; b=Vx7w9+w5S5IUfp7nCs/UJOdSWVY5setoLJZak2At2HGEH2ONAyQf5wb+nmNuafuPC WB2VoDSJ9EQTMVzuGG2L/C3bSk2E8hZXpxVaAdzz6j8maU3FMM3no5OB1WGGZeHF7G 2+/xea7/u2snZu75gMaxLtWRyo1msaoLanwqAN+Od+u+kz3ovQtZA3Oc5fx5vw/nik N0Z/0DA3UxWfNkr5DLRHBBCqDcTu29QswUvgTRHP9Q4Q1zmWUjPIHx0Mm7Ccv3MpZY L/Z0LCMxUNNE/8myCb5zA1RwJpzwgblH6m6fK8Scu0Hc4MDGaplBwPIm3RXFAC6GYg BAq5hA7mWtD5g== Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org There are four locations in gup.c that have a fair amount of code duplication. This means that changing one requires making the same changes in four places, not to mention reading the same code four times, and wondering if there are subtle differences. Factor out the common code into static functions, thus reducing the overall line count and the code's complexity. Also, take the opportunity to slightly improve the efficiency of the error cases, by doing a mass subtraction of the refcount, surrounded by get_page()/put_page(). Also, further simplify (slightly), by waiting until the the successful end of each routine, to increment *nr. Reviewed-by: Jérôme Glisse Cc: Jan Kara Cc: Ira Weiny Cc: Christoph Hellwig Cc: Aneesh Kumar K.V Signed-off-by: John Hubbard Reviewed-by: Jan Kara --- mm/gup.c | 91 ++++++++++++++++++++++---------------------------------- 1 file changed, 36 insertions(+), 55 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 85caf76b3012..f3c7d6625817 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1969,6 +1969,25 @@ static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr, } #endif +static int __record_subpages(struct page *page, unsigned long addr, + unsigned long end, struct page **pages) +{ + int nr; + + for (nr = 0; addr != end; addr += PAGE_SIZE) + pages[nr++] = page++; + + return nr; +} + +static void put_compound_head(struct page *page, int refs) +{ + /* Do a get_page() first, in case refs == page->_refcount */ + get_page(page); + page_ref_sub(page, refs); + put_page(page); +} + #ifdef CONFIG_ARCH_HAS_HUGEPD static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end, unsigned long sz) @@ -1998,32 +2017,20 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr, /* hugepages are never "special" */ VM_BUG_ON(!pfn_valid(pte_pfn(pte))); - refs = 0; head = pte_page(pte); - page = head + ((addr & (sz-1)) >> PAGE_SHIFT); - do { - VM_BUG_ON(compound_head(page) != head); - pages[*nr] = page; - (*nr)++; - page++; - refs++; - } while (addr += PAGE_SIZE, addr != end); + refs = __record_subpages(page, addr, end, pages + *nr); head = try_get_compound_head(head, refs); - if (!head) { - *nr -= refs; + if (!head) return 0; - } if (unlikely(pte_val(pte) != pte_val(*ptep))) { - /* Could be optimized better */ - *nr -= refs; - while (refs--) - put_page(head); + put_compound_head(head, refs); return 0; } + *nr += refs; SetPageReferenced(head); return 1; } @@ -2071,28 +2078,19 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, pages, nr); } - refs = 0; page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); - do { - pages[*nr] = page; - (*nr)++; - page++; - refs++; - } while (addr += PAGE_SIZE, addr != end); + refs = __record_subpages(page, addr, end, pages + *nr); head = try_get_compound_head(pmd_page(orig), refs); - if (!head) { - *nr -= refs; + if (!head) return 0; - } if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) { - *nr -= refs; - while (refs--) - put_page(head); + put_compound_head(head, refs); return 0; } + *nr += refs; SetPageReferenced(head); return 1; } @@ -2114,28 +2112,19 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, pages, nr); } - refs = 0; page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); - do { - pages[*nr] = page; - (*nr)++; - page++; - refs++; - } while (addr += PAGE_SIZE, addr != end); + refs = __record_subpages(page, addr, end, pages + *nr); head = try_get_compound_head(pud_page(orig), refs); - if (!head) { - *nr -= refs; + if (!head) return 0; - } if (unlikely(pud_val(orig) != pud_val(*pudp))) { - *nr -= refs; - while (refs--) - put_page(head); + put_compound_head(head, refs); return 0; } + *nr += refs; SetPageReferenced(head); return 1; } @@ -2151,28 +2140,20 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr, return 0; BUILD_BUG_ON(pgd_devmap(orig)); - refs = 0; + page = pgd_page(orig) + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT); - do { - pages[*nr] = page; - (*nr)++; - page++; - refs++; - } while (addr += PAGE_SIZE, addr != end); + refs = __record_subpages(page, addr, end, pages + *nr); head = try_get_compound_head(pgd_page(orig), refs); - if (!head) { - *nr -= refs; + if (!head) return 0; - } if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) { - *nr -= refs; - while (refs--) - put_page(head); + put_compound_head(head, refs); return 0; } + *nr += refs; SetPageReferenced(head); return 1; }