From patchwork Wed Dec 11 02:52:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11284169 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 B9371188B for ; Wed, 11 Dec 2019 02:57:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91E7B21556 for ; Wed, 11 Dec 2019 02:57:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="VS6zga5F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728114AbfLKC5k (ORCPT ); Tue, 10 Dec 2019 21:57:40 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:16074 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726619AbfLKCx1 (ORCPT ); Tue, 10 Dec 2019 21:53:27 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 10 Dec 2019 18:53:15 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Tue, 10 Dec 2019 18:53:22 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 10 Dec 2019 18:53:22 -0800 Received: from HQMAIL111.nvidia.com (172.20.187.18) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 11 Dec 2019 02:53:21 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Wed, 11 Dec 2019 02:53:21 +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, 10 Dec 2019 18:53:20 -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 v9 01/25] mm/gup: factor out duplicate code from four routines Date: Tue, 10 Dec 2019 18:52:54 -0800 Message-ID: <20191211025318.457113-2-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191211025318.457113-1-jhubbard@nvidia.com> References: <20191211025318.457113-1-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=1576032796; bh=NjEUDVUY50BsRhke7z2S9TxhDwSe8KFPL35zO7aJjtI=; 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=VS6zga5FiY7Vu66DRYjf2gKJmJHPntw8N8mBDsBSBO08ZCOCzw/y/IbIGZV7w6+rK E+0FFACMPbHQ8Ryk7Oh0Y+s6QwvjGNX5RFVxx65xXffaFuxKNEohDdD2uu2AeZGf8T 0aNaGlfh+cFBX66CJL9rmJ8Sfhg2Wjp8E17AsstVPnU2q+jf97ejc7LMnamFN+MquO 2souh8lQc9PrY4yN96BUULvxuG/fKmgjYyM04w35bMHMiSedO6olkvsI5KBpnLhtS6 0zjzxArIxB/90HbuneEtdobksiH9+Dxg/voSuHfJAuJJCMhD4L5rof98Otg3ghAxW3 HyRwaPmyoZPOQ== Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@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: Christoph Hellwig Reviewed-by: Jérôme Glisse Reviewed-by: Jan Kara Cc: Ira Weiny Cc: Christoph Hellwig Cc: Aneesh Kumar K.V Signed-off-by: John Hubbard --- mm/gup.c | 91 ++++++++++++++++++++++---------------------------------- 1 file changed, 36 insertions(+), 55 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 7646bf993b25..f764432914c4 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1978,6 +1978,25 @@ 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) @@ -2007,32 +2026,20 @@ 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; } @@ -2079,28 +2086,19 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, return __gup_device_huge_pmd(orig, pmdp, addr, end, 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; } @@ -2120,28 +2118,19 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, return __gup_device_huge_pud(orig, pudp, addr, end, 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; } @@ -2157,28 +2146,20 @@ 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; }