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charset="UTF-8" Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1574320437; bh=sKvmWb988RM84yP+egQhSiN41dObVjIOUVoMHE//spE=; 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=AABiJjmzLHly90Lc+tpSgWvQ2gkOLBSYLx+q1zdjNh8KcQhGmFmsHnn0Y5BGHpRJD lgauCr1HVm47H+VZMReB1beCsG5JEAaltjH32A42RpfeXBABxRH7jysaeIpaogLDkZ 8vVFkAkRSmHW4rTeElrnSY8BxawMss/QQfrXR6NVDNG3J/EiAwhHBmoa3hsNalR0R1 NEox93K3NNzsOwo/F3iWRgwraeHBU6qhr8MtkgZIHumtbLgVhvBfHBC2cOT7xMTeSJ FBTqNvemx2QSN1/9cmZo/T+p9xWcNyjvq/uK2CE2cqAq0m4K4xzqaaPXYYOE8SdXxC zlcdC2LZ1r8GQ== 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. Reviewed-by: J=C3=A9r=C3=B4me 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 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 *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; + + for (nr =3D 0; addr !=3D end; addr +=3D PAGE_SIZE) + pages[nr++] =3D page++; + + return nr; +} + +static void put_compound_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); +} + #ifdef CONFIG_ARCH_HAS_HUGEPD static unsigned long hugepte_addr_end(unsigned long addr, unsigned long en= d, unsigned long sz) @@ -1998,32 +2017,20 @@ 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); + put_compound_head(head, refs); return 0; } =20 + *nr +=3D refs; SetPageReferenced(head); return 1; } @@ -2071,28 +2078,19 @@ 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); + put_compound_head(head, refs); return 0; } =20 + *nr +=3D refs; SetPageReferenced(head); return 1; } @@ -2114,28 +2112,19 @@ 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); + put_compound_head(head, refs); return 0; } =20 + *nr +=3D refs; SetPageReferenced(head); return 1; } @@ -2151,28 +2140,20 @@ 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); + put_compound_head(head, refs); return 0; } =20 + *nr +=3D refs; SetPageReferenced(head); return 1; } --=20 2.24.0