From patchwork Sun Nov 3 21:17:57 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11224647 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 8721F13BD for ; Sun, 3 Nov 2019 21:20:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D63A21D71 for ; Sun, 3 Nov 2019 21:20:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="F+q+2Nm2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728421AbfKCVSV (ORCPT ); Sun, 3 Nov 2019 16:18:21 -0500 Received: from hqemgate16.nvidia.com ([216.228.121.65]:10534 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728121AbfKCVSS (ORCPT ); Sun, 3 Nov 2019 16:18:18 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Sun, 03 Nov 2019 13:18:22 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Sun, 03 Nov 2019 13:18:15 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Sun, 03 Nov 2019 13:18:15 -0800 Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Sun, 3 Nov 2019 21:18:15 +0000 Received: from hqnvemgw01.nvidia.com (172.20.150.20) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Sun, 3 Nov 2019 21:18:15 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Sun, 03 Nov 2019 13:18:14 -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 v2 02/18] mm/gup: factor out duplicate code from four routines Date: Sun, 3 Nov 2019 13:17:57 -0800 Message-ID: <20191103211813.213227-3-jhubbard@nvidia.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191103211813.213227-1-jhubbard@nvidia.com> References: <20191103211813.213227-1-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=1572815902; bh=kaGNIHbfja+uY6cKXyOxb4P0f0fYoWBJW4uSclr3zkQ=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=F+q+2Nm2ah/6kNgKZO4cO9APqojvmMVAYoNWjgqqiwuDdQ8AP4EoxEyVuWbTt8N2x 0+gD4dEhHTWFLjxwoxODmXiRboHOHRebRhnxK6rrF/aN6FezATSRMkoofDhN+Kuzhc 98lFHWFikPv2z7wfnG6mSw5YYZPL8XOTsZfY+FbjSEBKpSjlQnNQMjobgvNx0k8n70 il61zIlP+u2wVU/NhvddF6W54orHnMnHFeueINqCQkIh5mazHUKZlAPnI7TOBul3P0 2tFEv+/R43mvXKPVCaEFILRD5ZM9jAljSrGESHyz+w6X9AmZw/Frq+aOpSSUHsEtTl ds+UW1ym+06oQ== 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. Cc: Ira Weiny Cc: Christoph Hellwig Cc: Aneesh Kumar K.V Signed-off-by: John Hubbard Reviewed-by: Jérôme Glisse --- mm/gup.c | 104 ++++++++++++++++++++++++------------------------------- 1 file changed, 45 insertions(+), 59 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 85caf76b3012..199da99e8ffc 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1969,6 +1969,34 @@ 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) +{ + int nr_recorded_pages = 0; + + do { + pages[nr] = page; + nr++; + page++; + nr_recorded_pages++; + } while (addr += PAGE_SIZE, addr != end); + return nr_recorded_pages; +} + +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); +} + +static void __huge_pt_done(struct page *head, int nr_recorded_pages, int *nr) +{ + *nr += nr_recorded_pages; + SetPageReferenced(head); +} + #ifdef CONFIG_ARCH_HAS_HUGEPD static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end, unsigned long sz) @@ -1998,33 +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; } - SetPageReferenced(head); + __huge_pt_done(head, refs, nr); return 1; } @@ -2071,29 +2086,19 @@ 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; } - SetPageReferenced(head); + __huge_pt_done(head, refs, nr); return 1; } @@ -2114,29 +2119,19 @@ 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; } - SetPageReferenced(head); + __huge_pt_done(head, refs, nr); return 1; } @@ -2151,29 +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; } - SetPageReferenced(head); + __huge_pt_done(head, refs, nr); return 1; }