From patchwork Fri Dec 11 15:58:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 69988 Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from ) id 1knkrA-00FTEx-AO; Fri, 11 Dec 2020 16:01:21 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406661AbgLKQAr (ORCPT + 1 other); Fri, 11 Dec 2020 11:00:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406345AbgLKP7i (ORCPT ); Fri, 11 Dec 2020 10:59:38 -0500 Received: from mail-wm1-x344.google.com (mail-wm1-x344.google.com [IPv6:2a00:1450:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 536EDC061793 for ; Fri, 11 Dec 2020 07:58:54 -0800 (PST) Received: by mail-wm1-x344.google.com with SMTP id q75so9047193wme.2 for ; Fri, 11 Dec 2020 07:58:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=243Gvg3EOSmTTvBu4o4RKVn/UX2SWUWrVcKX752oh38=; b=Id21eySxih7XsO5kncW+YAXadbd1FJRP3AnY8TzDzyRyz5vVVokfWt6LARnKv+mD6i xuXPXb4DkBzcRfsCwW9KZQ9udP/p+NrzbHAjO1Qv2ykiye5kdGDuJOGNzC/uPI1NH/0R gPKG1sdfMW2SydMRmu4eAZjGA3/gSSRFu/ySs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=243Gvg3EOSmTTvBu4o4RKVn/UX2SWUWrVcKX752oh38=; b=iYp42eROacNZwaOCfNuxWtYZsguygyU5wZ2QlKkiH5yWcvCBHYipfpD1vlV4y3fyrL I4fyquFlC/ms5S0++A46YcfHcTVHe5J40q4+oJzYwwKi3DGTISsXCrLYmUoE+GMk4uQH ld+XHyztnKzq0jc0Q2APbRwu3GvaJSMv4sVCH/03d4vkW4QX6f8XRzIuFZ7HkSSyN1lf NSiZ8bpDvejoMq2W8XTZLi1DlwrPB18Zup7Osia7VkBlRxRe+uEjkzaTQFuAmpEGlWJf KkvmqLuJqtpnhoH3/YBeLAyi11tsPYJyc2blBpPXd2QaFZv7M3/VzdFmgME7g7Xb6YT2 XvYg== X-Gm-Message-State: AOAM533DHh9qs911qbWCP3ETYp3cC1keouAi9u+Ra0OY9wkSdTZ8ZGZH xYPsmct6uEOlEAa95dosoQmucg== X-Google-Smtp-Source: ABdhPJyuJvI2Mjy8AtPGb0Iyw00NTdMFlmVvHC+yg+8Gjr8dEU+KJmhpBUiwqBVmfmlnpv1AVmn/+w== X-Received: by 2002:a1c:4904:: with SMTP id w4mr13987630wma.140.1607702333034; Fri, 11 Dec 2020 07:58:53 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id z21sm14828241wmk.20.2020.12.11.07.58.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Dec 2020 07:58:52 -0800 (PST) From: Daniel Vetter To: DRI Development Cc: Intel Graphics Development , Daniel Vetter , Daniel Vetter , Thomas Zimmermann , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org Subject: [PATCH 4/4] dma-buf: doc polish for pin/unpin Date: Fri, 11 Dec 2020 16:58:43 +0100 Message-Id: <20201211155843.3348718-4-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201211155843.3348718-1-daniel.vetter@ffwll.ch> References: <20201211155843.3348718-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -2.5 (--) X-LSpam-Report: No, score=-2.5 required=5.0 tests=BAYES_00=-1.9,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1 autolearn=ham autolearn_force=no Motivated by a discussion with Christian and Thomas: Try to untangle a bit what's relevant for importers and what's relevant for exporters. Also add an assert that really only dynamic importers use the api function, anything else doesn't make sense. Signed-off-by: Daniel Vetter Cc: Thomas Zimmermann Cc: Sumit Semwal Cc: "Christian König" Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org --- drivers/dma-buf/dma-buf.c | 19 ++++++++++++++++--- include/linux/dma-buf.h | 8 +++++--- 2 files changed, 21 insertions(+), 6 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 00d5afe904cc..1065545e9ca1 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -809,9 +809,15 @@ EXPORT_SYMBOL_GPL(dma_buf_detach); /** * dma_buf_pin - Lock down the DMA-buf - * * @attach: [in] attachment which should be pinned * + * Only dynamic importers (who set up @attach with dma_buf_dynamic_attach()) may + * call this, and only for limited use cases like scanout and not for temporary + * pin operations. It is not permitted to allow userspace to pin arbitrary + * amounts of buffers through this interface. + * + * Buffers must be unpinned by calling dma_buf_unpin(). + * * Returns: * 0 on success, negative error code on failure. */ @@ -820,6 +826,8 @@ int dma_buf_pin(struct dma_buf_attachment *attach) struct dma_buf *dmabuf = attach->dmabuf; int ret = 0; + WARN_ON(!dma_buf_attachment_is_dynamic(attach)); + dma_resv_assert_held(dmabuf->resv); if (dmabuf->ops->pin) @@ -830,14 +838,19 @@ int dma_buf_pin(struct dma_buf_attachment *attach) EXPORT_SYMBOL_GPL(dma_buf_pin); /** - * dma_buf_unpin - Remove lock from DMA-buf - * + * dma_buf_unpin - Unpin a DMA-buf * @attach: [in] attachment which should be unpinned + * + * This unpins a buffer pinned by dma_buf_pin() and allows the exporter to move + * any mapping of @attach again and inform the importer through + * &dma_buf_attach_ops.move_notify. */ void dma_buf_unpin(struct dma_buf_attachment *attach) { struct dma_buf *dmabuf = attach->dmabuf; + WARN_ON(!dma_buf_attachment_is_dynamic(attach)); + dma_resv_assert_held(dmabuf->resv); if (dmabuf->ops->unpin) diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 43802a31b25d..628681bf6c99 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -86,13 +86,15 @@ struct dma_buf_ops { * @pin: * * This is called by dma_buf_pin() and lets the exporter know that the - * DMA-buf can't be moved any more. + * DMA-buf can't be moved any more. The exporter should pin the buffer + * into system memory to make sure it is generally accessible by other + * devices. * * This is called with the &dmabuf.resv object locked and is mutual * exclusive with @cache_sgt_mapping. * - * This callback is optional and should only be used in limited use - * cases like scanout and not for temporary pin operations. + * This is called automatically for non-dynamic importers from + * dma_buf_attach(). * * Returns: *