From: John Hubbard <jhubbard@nvidia.com> To: Jan Kara <jack@suse.cz> Cc: "Andrew Morton" <akpm@linux-foundation.org>, "Al Viro" <viro@zeniv.linux.org.uk>, "Alex Williamson" <alex.williamson@redhat.com>, "Benjamin Herrenschmidt" <benh@kernel.crashing.org>, "Björn Töpel" <bjorn.topel@intel.com>, "Christoph Hellwig" <hch@infradead.org>, "Dan Williams" <dan.j.williams@intel.com>, "Daniel Vetter" <daniel@ffwll.ch>, "Dave Chinner" <david@fromorbit.com>, "David Airlie" <airlied@linux.ie>, "David S . Miller" <davem@davemloft.net>, "Ira Weiny" <ira.weiny@intel.com>, "Jason Gunthorpe" <jgg@ziepe.ca>, "Jens Axboe" <axboe@kernel.dk>, "Jonathan Corbet" <corbet@lwn.net>, "Jérôme Glisse" <jglisse@redhat.com>, "Magnus Karlsson" <magnus.karlsson@intel.com>, "Mauro Carvalho Chehab" <mchehab@kernel.org>, "Michael Ellerman" <mpe@ellerman> Subject: Re: [PATCH v5 02/24] mm/gup: factor out duplicate code from four routines Date: Mon, 18 Nov 2019 23:00:33 -0800 [thread overview] Message-ID: <152e2ea9-edd9-f868-7731-ff467d692f5f@nvidia.com> (raw) In-Reply-To: <20191118094604.GC17319@quack2.suse.cz> On 11/18/19 1:46 AM, Jan Kara wrote: > On Thu 14-11-19 21:53:18, John Hubbard wrote: >> 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 <jglisse@redhat.com> >> Cc: Jan Kara <jack@suse.cz> >> Cc: Ira Weiny <ira.weiny@intel.com> >> Cc: Christoph Hellwig <hch@lst.de> >> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> >> Signed-off-by: John Hubbard <jhubbard@nvidia.com> >> --- >> mm/gup.c | 95 ++++++++++++++++++++++++-------------------------------- >> 1 file changed, 40 insertions(+), 55 deletions(-) >> >> diff --git a/mm/gup.c b/mm/gup.c >> index 85caf76b3012..858541ea30ce 100644 >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -1969,6 +1969,29 @@ 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 = 0; >> + int nr_recorded_pages = 0; >> + >> + do { >> + pages[nr] = page; >> + nr++; >> + page++; >> + nr_recorded_pages++; >> + } while (addr += PAGE_SIZE, addr != end); >> + return nr_recorded_pages; > > nr == nr_recorded_pages so no need for both... BTW, structuring this as a > for loop would be probably more logical and shorter now: > > for (nr = 0; addr != end; addr += PAGE_SIZE) > pages[nr++] = page++; > return nr; > Nice touch, I've applied it. thanks, -- John Hubbard NVIDIA > The rest of the patch looks good to me. > > Honza >
WARNING: multiple messages have this Message-ID (diff)
From: John Hubbard <jhubbard@nvidia.com> To: Jan Kara <jack@suse.cz> Cc: "Michal Hocko" <mhocko@suse.com>, kvm@vger.kernel.org, linux-doc@vger.kernel.org, "David Airlie" <airlied@linux.ie>, "Dave Chinner" <david@fromorbit.com>, dri-devel@lists.freedesktop.org, LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org, "Paul Mackerras" <paulus@samba.org>, linux-kselftest@vger.kernel.org, "Ira Weiny" <ira.weiny@intel.com>, "Christoph Hellwig" <hch@lst.de>, "Jonathan Corbet" <corbet@lwn.net>, linux-rdma@vger.kernel.org, "Michael Ellerman" <mpe@ellerman.id.au>, "Christoph Hellwig" <hch@infradead.org>, "Jason Gunthorpe" <jgg@ziepe.ca>, "Vlastimil Babka" <vbabka@suse.cz>, "Björn Töpel" <bjorn.topel@intel.com>, linux-media@vger.kernel.org, "Shuah Khan" <shuah@kernel.org>, linux-block@vger.kernel.org, "Jérôme Glisse" <jglisse@redhat.com>, "Al Viro" <viro@zeniv.linux.org.uk>, "Dan Williams" <dan.j.williams@intel.com>, "Mauro Carvalho Chehab" <mchehab@kernel.org>, bpf@vger.kernel.org, "Magnus Karlsson" <magnus.karlsson@intel.com>, "Jens Axboe" <axboe@kernel.dk>, netdev@vger.kernel.org, "Alex Williamson" <alex.williamson@redhat.com>, "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>, linux-fsdevel@vger.kernel.org, "Andrew Morton" <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org, "David S . Miller" <davem@davemloft.net>, "Mike Kravetz" <mike.kravetz@oracle.com> Subject: Re: [PATCH v5 02/24] mm/gup: factor out duplicate code from four routines Date: Mon, 18 Nov 2019 23:00:33 -0800 [thread overview] Message-ID: <152e2ea9-edd9-f868-7731-ff467d692f5f@nvidia.com> (raw) Message-ID: <20191119070033.eQnldbCy7mtWTVU3KpkraY3Ozb4bQuxZXMgMGZiSupE@z> (raw) In-Reply-To: <20191118094604.GC17319@quack2.suse.cz> On 11/18/19 1:46 AM, Jan Kara wrote: > On Thu 14-11-19 21:53:18, John Hubbard wrote: >> 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 <jglisse@redhat.com> >> Cc: Jan Kara <jack@suse.cz> >> Cc: Ira Weiny <ira.weiny@intel.com> >> Cc: Christoph Hellwig <hch@lst.de> >> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> >> Signed-off-by: John Hubbard <jhubbard@nvidia.com> >> --- >> mm/gup.c | 95 ++++++++++++++++++++++++-------------------------------- >> 1 file changed, 40 insertions(+), 55 deletions(-) >> >> diff --git a/mm/gup.c b/mm/gup.c >> index 85caf76b3012..858541ea30ce 100644 >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -1969,6 +1969,29 @@ 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 = 0; >> + int nr_recorded_pages = 0; >> + >> + do { >> + pages[nr] = page; >> + nr++; >> + page++; >> + nr_recorded_pages++; >> + } while (addr += PAGE_SIZE, addr != end); >> + return nr_recorded_pages; > > nr == nr_recorded_pages so no need for both... BTW, structuring this as a > for loop would be probably more logical and shorter now: > > for (nr = 0; addr != end; addr += PAGE_SIZE) > pages[nr++] = page++; > return nr; > Nice touch, I've applied it. thanks, -- John Hubbard NVIDIA > The rest of the patch looks good to me. > > Honza > _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2019-11-19 7:00 UTC|newest] Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-11-15 5:53 [PATCH v5 00/24] mm/gup: track dma-pinned pages: FOLL_PIN John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 01/24] mm/gup: pass flags arg to __gup_device_* functions John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 02/24] mm/gup: factor out duplicate code from four routines John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-18 9:46 ` Jan Kara 2019-11-18 9:46 ` Jan Kara 2019-11-19 7:00 ` John Hubbard [this message] 2019-11-19 7:00 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 03/24] mm/gup: move try_get_compound_head() to top, fix minor issues John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 04/24] mm: Cleanup __put_devmap_managed_page() vs ->page_free() John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 05/24] mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 06/24] goldish_pipe: rename local pin_user_pages() routine John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-18 9:47 ` Jan Kara 2019-11-18 9:47 ` Jan Kara 2019-11-15 5:53 ` [PATCH v5 07/24] IB/umem: use get_user_pages_fast() to pin DMA pages John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-18 9:49 ` Jan Kara 2019-11-18 9:49 ` Jan Kara 2019-11-15 5:53 ` [PATCH v5 08/24] media/v4l2-core: set pages dirty upon releasing DMA buffers John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 09/24] vfio, mm: fix get_user_pages_remote() and FOLL_LONGTERM John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 14:08 ` Jason Gunthorpe 2019-11-15 18:06 ` Ira Weiny 2019-11-15 18:06 ` Ira Weiny 2019-11-15 5:53 ` [PATCH v5 10/24] mm/gup: introduce pin_user_pages*() and FOLL_PIN John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-18 10:16 ` Jan Kara 2019-11-18 10:16 ` Jan Kara 2019-11-19 5:17 ` John Hubbard 2019-11-19 5:17 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 11/24] goldish_pipe: convert to pin_user_pages() and put_user_page() John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-18 10:16 ` Jan Kara 2019-11-18 10:16 ` Jan Kara 2019-11-15 5:53 ` [PATCH v5 12/24] IB/{core, hw, umem}: set FOLL_PIN via pin_user_pages*(), fix up ODP John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 14:09 ` [PATCH v5 12/24] IB/{core,hw,umem}: " Jason Gunthorpe 2019-11-15 5:53 ` [PATCH v5 13/24] mm/process_vm_access: set FOLL_PIN via pin_user_pages_remote() John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-18 10:30 ` Jan Kara 2019-11-18 10:30 ` Jan Kara 2019-11-15 5:53 ` [PATCH v5 14/24] drm/via: set FOLL_PIN via pin_user_pages_fast() John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 15/24] fs/io_uring: set FOLL_PIN via pin_user_pages() John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-18 10:34 ` Jan Kara 2019-11-18 10:34 ` Jan Kara 2019-11-15 5:53 ` [PATCH v5 16/24] net/xdp: " John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 17/24] mm/gup: track FOLL_PIN pages John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-18 11:58 ` Jan Kara 2019-11-18 11:58 ` Jan Kara 2019-11-19 0:22 ` John Hubbard 2019-11-19 0:22 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 18/24] media/v4l2-core: pin_user_pages (FOLL_PIN) and put_user_page() conversion John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 19/24] vfio, mm: " John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 20/24] powerpc: book3s64: convert to pin_user_pages() and put_user_page() John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 21/24] mm/gup_benchmark: use proper FOLL_WRITE flags instead of hard-coding "1" John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 22/24] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 23/24] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard 2019-11-15 5:53 ` John Hubbard 2019-11-15 5:53 ` [PATCH v5 24/24] mm, tree-wide: rename put_user_page*() to unpin_user_page*() John Hubbard 2019-11-15 5:53 ` John Hubbard
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