From patchwork Thu Sep 19 15:08:53 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11152765 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 CF5091599 for ; Thu, 19 Sep 2019 15:09:22 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B79CB21848 for ; Thu, 19 Sep 2019 15:09:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B79CB21848 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 586896F45D; Thu, 19 Sep 2019 15:09:20 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3343D6F45D; Thu, 19 Sep 2019 15:09:19 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 18547617-1500050 for multiple; Thu, 19 Sep 2019 16:08:55 +0100 From: Chris Wilson To: dri-devel@lists.freedesktop.org Subject: [PATCH] dma-buf: Implement simple read/write vfs ops Date: Thu, 19 Sep 2019 16:08:53 +0100 Message-Id: <20190919150853.18181-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org, Sean Paul , Janusz Krzysztofik Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" It is expected that processes will pass dma-buf fd between drivers, and only using the fd themselves for mmaping and synchronisation ioctls. However, it may be convenient for an application to read/write into the dma-buf, for instance a test case to check the internal dma_buf->ops->kmap interface. There may also be a small advantage to avoiding the mmap() for very simple/small operations. Note in particular, synchronisation with the device is left to the caller with an explicit DMA_BUF_IOCTL_SYNC, rather than done implicitly inside the read/write, so that the user can avoid synchronisation if they so choose. "It is easier to add synchronisation later, than it is to take it away." v2: Lots of little fixes, plus a real llseek() implements so that the first basic little test cases work! Testcase: igt/prime_rw Signed-off-by: Chris Wilson Cc: Laura Abbott Cc: Sumit Semwal Cc: Daniel Vetter Cc: Sean Paul Cc: Janusz Krzysztofik Tested-by: Laura Abbott --- Dusting this off again as it would be nice as a user to operate on dmabuf agnostic to the underyling driver. We have mmap, so naturally we would like to have read/write as well! --- drivers/dma-buf/dma-buf.c | 108 ++++++++++++++++++++++++++++++++------ 1 file changed, 93 insertions(+), 15 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 433d91d710e4..a19fc881a99c 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -135,28 +135,104 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence) { - struct dma_buf *dmabuf; - loff_t base; + struct dma_buf *dmabuf = file->private_data; if (!is_dma_buf_file(file)) return -EBADF; - dmabuf = file->private_data; + return fixed_size_llseek(file, offset, whence, dmabuf->size); +} - /* only support discovering the end of the buffer, - but also allow SEEK_SET to maintain the idiomatic - SEEK_END(0), SEEK_CUR(0) pattern */ - if (whence == SEEK_END) - base = dmabuf->size; - else if (whence == SEEK_SET) - base = 0; - else - return -EINVAL; +static ssize_t dma_buf_read(struct file *file, + char __user *ubuf, size_t remain, + loff_t *offset) +{ + struct dma_buf *dmabuf = file->private_data; + unsigned long idx; + unsigned int start; + size_t total; - if (offset != 0) - return -EINVAL; + if (!is_dma_buf_file(file)) + return -EBADF; + + total = 0; + idx = *offset >> PAGE_SHIFT; + start = offset_in_page(*offset); + while (remain) { + unsigned int len = min_t(size_t, remain, PAGE_SIZE - start); + unsigned int copied; + void *vaddr; + + if (*offset >= dmabuf->size) + return total; + + vaddr = dma_buf_kmap(dmabuf, idx); + if (!vaddr) + return total ?: -EIO; + + copied = copy_to_user(ubuf, vaddr + start, len); + dma_buf_kunmap(dmabuf, idx, vaddr); + + total += copied ?: len; + if (copied) { + *offset += copied; + return total ?: -EFAULT; + } + + remain -= len; + *offset += len; + ubuf += len; + start = 0; + idx++; + } + + return total; +} + +static ssize_t dma_buf_write(struct file *file, + const char __user *ubuf, size_t remain, + loff_t *offset) +{ + struct dma_buf *dmabuf = file->private_data; + unsigned long idx; + unsigned int start; + size_t total; + + if (!is_dma_buf_file(file)) + return -EBADF; + + total = 0; + idx = *offset >> PAGE_SHIFT; + start = offset_in_page(*offset); + while (remain) { + unsigned int len = min_t(size_t, remain, PAGE_SIZE - start); + unsigned int copied; + void *vaddr; + + if (*offset >= dmabuf->size) + return total; + + vaddr = dma_buf_kmap(dmabuf, idx); + if (!vaddr) + return total ?: -EIO; + + copied = copy_from_user(vaddr + start, ubuf, len); + dma_buf_kunmap(dmabuf, idx, vaddr); + + total += copied ?: len; + if (copied) { + *offset += copied; + return total ?: -EFAULT; + } + + remain -= len; + *offset += len; + ubuf += len; + start = 0; + idx++; + } - return base + offset; + return total; } /** @@ -413,6 +489,8 @@ static const struct file_operations dma_buf_fops = { .release = dma_buf_release, .mmap = dma_buf_mmap_internal, .llseek = dma_buf_llseek, + .read = dma_buf_read, + .write = dma_buf_write, .poll = dma_buf_poll, .unlocked_ioctl = dma_buf_ioctl, #ifdef CONFIG_COMPAT