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Wed, 30 Oct 2019 15:49:35 -0700 From: John Hubbard To: Andrew Morton Subject: [PATCH 02/19] mm/gup: factor out duplicate code from four routines Date: Wed, 30 Oct 2019 15:49:13 -0700 Message-ID: <20191030224930.3990755-3-jhubbard@nvidia.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191030224930.3990755-1-jhubbard@nvidia.com> References: <20191030224930.3990755-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public Content-Transfer-Encoding: quoted-printable Content-Type: text/plain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1572475783; bh=tBh63Up4GmYWMpZfv2SoHkQER3l3/AwmpTx4CmGyUOY=; 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=q6Q/A8TBBZ55PyF/FZZqYnJ+lgBDwYNDtC48DaucDzCF0TjR8x89MUFmfJrXfVIy8 YhLIOpQBeIReIooXA8TPZibffV6cpNr4lEyyTxNLOCl4fSlAiNzImWEmpAHpBQAgnm 2VJfy72jnhXV4Na9artoMHPQqpC3lkGe4ymiRJWOT1WeuiuvX5ZsQGDmnAJG4LGImR 9ty1Onsdh/I+zLky4Hr6hnCHYagTmLcM/PUFXTvUJ2RHGzNqzx9q0kjJ96JHXHJJWk 2oGM89HTfGbtaCai1JlzNt3fE78ewH7qAVLMEPdwaEG9DhYOb9MPVg/HVxjVhX4dEl BY9wQk9uQlmQw== X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Hocko , Jan Kara , kvm@vger.kernel.org, linux-doc@vger.kernel.org, David Airlie , Dave Chinner , dri-devel@lists.freedesktop.org, LKML , linux-mm@kvack.org, Paul Mackerras , linux-kselftest@vger.kernel.org, Ira Weiny , Christoph Hellwig , Jonathan Corbet , linux-rdma@vger.kernel.org, Christoph Hellwig , Jason Gunthorpe , Vlastimil Babka , =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , linux-media@vger.kernel.org, Shuah Khan , John Hubbard , linux-block@vger.kernel.org, =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Al Viro , Dan Williams , Mauro Carvalho Chehab , Magnus Karlsson , Jens Axboe , netdev@vger.kernel.org, Alex Williamson , Daniel Vetter , "Aneesh Kumar K . V" , linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "David S . Miller" , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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: Christoph Hellwig Cc: Aneesh Kumar K.V Signed-off-by: John Hubbard --- mm/gup.c | 113 ++++++++++++++++++++++--------------------------------- 1 file changed, 46 insertions(+), 67 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 85caf76b3012..8fb0d9cdfaf5 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1969,6 +1969,35 @@ static int __gup_device_huge_pud(pud_t pud, pud_t *p= udp, unsigned long addr, } #endif =20 +static int __record_subpages(struct page *page, unsigned long addr, + unsigned long end, struct page **pages, int nr) +{ + int nr_recorded_pages =3D 0; + + do { + pages[nr] =3D page; + nr++; + page++; + nr_recorded_pages++; + } while (addr +=3D PAGE_SIZE, addr !=3D end); + return nr_recorded_pages; +} + +static void __remove_refs_from_head(struct page *page, int refs) +{ + /* Do a get_page() first, in case refs =3D=3D page->_refcount */ + get_page(page); + page_ref_sub(page, refs); + put_page(page); +} + +static int __huge_pt_done(struct page *head, int nr_recorded_pages, int *n= r) +{ + *nr +=3D nr_recorded_pages; + SetPageReferenced(head); + return 1; +} + #ifdef CONFIG_ARCH_HAS_HUGEPD static unsigned long hugepte_addr_end(unsigned long addr, unsigned long en= d, unsigned long sz) @@ -1998,34 +2027,19 @@ static int gup_hugepte(pte_t *ptep, unsigned long s= z, unsigned long addr, /* hugepages are never "special" */ VM_BUG_ON(!pfn_valid(pte_pfn(pte))); =20 - refs =3D 0; head =3D pte_page(pte); - page =3D head + ((addr & (sz-1)) >> PAGE_SHIFT); - do { - VM_BUG_ON(compound_head(page) !=3D head); - pages[*nr] =3D page; - (*nr)++; - page++; - refs++; - } while (addr +=3D PAGE_SIZE, addr !=3D end); + refs =3D __record_subpages(page, addr, end, pages, *nr); =20 head =3D try_get_compound_head(head, refs); - if (!head) { - *nr -=3D refs; + if (!head) return 0; - } =20 if (unlikely(pte_val(pte) !=3D pte_val(*ptep))) { - /* Could be optimized better */ - *nr -=3D refs; - while (refs--) - put_page(head); + __remove_refs_from_head(head, refs); return 0; } - - SetPageReferenced(head); - return 1; + return __huge_pt_done(head, refs, nr); } =20 static int gup_huge_pd(hugepd_t hugepd, unsigned long addr, @@ -2071,30 +2085,18 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, un= signed long addr, pages, nr); } =20 - refs =3D 0; page =3D pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); - do { - pages[*nr] =3D page; - (*nr)++; - page++; - refs++; - } while (addr +=3D PAGE_SIZE, addr !=3D end); + refs =3D __record_subpages(page, addr, end, pages, *nr); =20 head =3D try_get_compound_head(pmd_page(orig), refs); - if (!head) { - *nr -=3D refs; + if (!head) return 0; - } =20 if (unlikely(pmd_val(orig) !=3D pmd_val(*pmdp))) { - *nr -=3D refs; - while (refs--) - put_page(head); + __remove_refs_from_head(head, refs); return 0; } - - SetPageReferenced(head); - return 1; + return __huge_pt_done(head, refs, nr); } =20 static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, @@ -2114,30 +2116,18 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, un= signed long addr, pages, nr); } =20 - refs =3D 0; page =3D pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); - do { - pages[*nr] =3D page; - (*nr)++; - page++; - refs++; - } while (addr +=3D PAGE_SIZE, addr !=3D end); + refs =3D __record_subpages(page, addr, end, pages, *nr); =20 head =3D try_get_compound_head(pud_page(orig), refs); - if (!head) { - *nr -=3D refs; + if (!head) return 0; - } =20 if (unlikely(pud_val(orig) !=3D pud_val(*pudp))) { - *nr -=3D refs; - while (refs--) - put_page(head); + __remove_refs_from_head(head, refs); return 0; } - - SetPageReferenced(head); - return 1; + return __huge_pt_done(head, refs, nr); } =20 static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr, @@ -2151,30 +2141,19 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, un= signed long addr, return 0; =20 BUILD_BUG_ON(pgd_devmap(orig)); - refs =3D 0; + page =3D pgd_page(orig) + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT); - do { - pages[*nr] =3D page; - (*nr)++; - page++; - refs++; - } while (addr +=3D PAGE_SIZE, addr !=3D end); + refs =3D __record_subpages(page, addr, end, pages, *nr); =20 head =3D try_get_compound_head(pgd_page(orig), refs); - if (!head) { - *nr -=3D refs; + if (!head) return 0; - } =20 if (unlikely(pgd_val(orig) !=3D pgd_val(*pgdp))) { - *nr -=3D refs; - while (refs--) - put_page(head); + __remove_refs_from_head(head, refs); return 0; } - - SetPageReferenced(head); - return 1; + return __huge_pt_done(head, refs, nr); } =20 static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, --=20 2.23.0