From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout4.w1.samsung.com ([210.118.77.14]:23745 "EHLO mailout4.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756206Ab3KZLUo (ORCPT ); Tue, 26 Nov 2013 06:20:44 -0500 Received: from eucpsbgm2.samsung.com (unknown [203.254.199.245]) by mailout4.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MWV00LJ8BIIJA90@mailout4.w1.samsung.com> for linux-media@vger.kernel.org; Tue, 26 Nov 2013 11:20:42 +0000 (GMT) Message-id: <52948409.3070500@samsung.com> Date: Tue, 26 Nov 2013 12:20:41 +0100 From: Marek Szyprowski MIME-version: 1.0 To: Ricardo Ribalda Delgado , Pawel Osciak , Mauro Carvalho Chehab , "open list:VIDEOBUF2 FRAMEWORK" , sylvester.nawrocki@gmail.com Subject: Re: [PATCH] videobuf2-dma-sg: Support io userptr operations on io memory References: <1383767329-29985-1-git-send-email-ricardo.ribalda@gmail.com> In-reply-to: <1383767329-29985-1-git-send-email-ricardo.ribalda@gmail.com> Content-type: text/plain; charset=UTF-8; format=flowed Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hello, On 2013-11-06 20:48, Ricardo Ribalda Delgado wrote: > Memory exported via remap_pfn_range cannot be remapped via > get_user_pages. > > Other videobuf2 methods (like the dma-contig) supports io memory. > > This patch adds support for this kind of memory. > > Signed-off-by: Ricardo Ribalda Delgado > --- > drivers/media/v4l2-core/videobuf2-dma-sg.c | 35 ++++++++++++++++++++++++++---- > 1 file changed, 31 insertions(+), 4 deletions(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c > index 2f86054..44ddfe1 100644 > --- a/drivers/media/v4l2-core/videobuf2-dma-sg.c > +++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c > @@ -40,6 +40,7 @@ struct vb2_dma_sg_buf { > unsigned int num_pages; > atomic_t refcount; > struct vb2_vmarea_handler handler; > + struct vm_area_struct *vma; > }; > > static void vb2_dma_sg_put(void *buf_priv); > @@ -155,6 +156,11 @@ static void vb2_dma_sg_put(void *buf_priv) > } > } > > +static inline int vma_is_io(struct vm_area_struct *vma) > +{ > + return !!(vma->vm_flags & (VM_IO | VM_PFNMAP)); > +} > + > static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr, > unsigned long size, int write) > { > @@ -180,7 +186,26 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr, > if (!buf->pages) > return NULL; > > - num_pages_from_user = get_user_pages(current, current->mm, > + buf->vma = find_vma(current->mm, vaddr); > + if (!buf->vma) { > + dprintk(1, "no vma for address %lu\n", vaddr); > + return NULL; > + } > + > + if (vma_is_io(buf->vma)) { > + for (num_pages_from_user = 0; > + num_pages_from_user < buf->num_pages; > + ++num_pages_from_user, vaddr += PAGE_SIZE) { > + unsigned long pfn; > + > + if (follow_pfn(buf->vma, vaddr, &pfn)) { > + dprintk(1, "no page for address %lu\n", vaddr); > + break; > + } Please add a call to vb2_get_vma(vma) to protect that io memory from being freed, see videobuf2-dma-contig.c for the reference. It is not 100% perfect way, but right now it works for the typical memory regions created by other multimedia devices. You will also need to call vb2_put_vma() later on release. > + buf->pages[num_pages_from_user] = pfn_to_page(pfn); > + } > + } else > + num_pages_from_user = get_user_pages(current, current->mm, > vaddr & PAGE_MASK, > buf->num_pages, > write, > @@ -201,8 +226,9 @@ userptr_fail_alloc_table_from_pages: > userptr_fail_get_user_pages: > dprintk(1, "get_user_pages requested/got: %d/%d]\n", > num_pages_from_user, buf->num_pages); > - while (--num_pages_from_user >= 0) > - put_page(buf->pages[num_pages_from_user]); > + if (!vma_is_io(buf->vma)) > + while (--num_pages_from_user >= 0) > + put_page(buf->pages[num_pages_from_user]); > kfree(buf->pages); > kfree(buf); > return NULL; > @@ -225,7 +251,8 @@ static void vb2_dma_sg_put_userptr(void *buf_priv) > while (--i >= 0) { > if (buf->write) > set_page_dirty_lock(buf->pages[i]); > - put_page(buf->pages[i]); > + if (!vma_is_io(buf->vma)) > + put_page(buf->pages[i]); > } > kfree(buf->pages); > kfree(buf); Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland