From nobody Thu Apr 9 19:21:01 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AFB6937DE8F for ; Fri, 6 Mar 2026 10:37:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772793451; cv=none; b=EnlGMlnVenPQgKhvvzy5kLxGc4u3D32Zh7sCr6ukMQdh6UBRPvpVrbgsgjlPaBALEwlaIrFiGNyEREb3u9eOO9ipFlMusLXgfdIZapQ5BW/Bjt2lhIYyY3Tc8EdEbU0kPxPJZorePG/Q8oup+5J+EhW9rqdswBKz/22/vLyVesE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772793451; c=relaxed/simple; bh=jnEWfPpzZhM9PT5/4IIyDdYQm5qsF5MEa9uiNa9/840=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ageCHetnCSlsSLb63v5HIW/3LYgPM0iEtsZ2+gTsHcV5esh9rfPapDzRDh+pgWMIm6CkIGnNFswN2f+yZqNjpLb+bCyk8uXzfbfhHB1xRVsza8cDmllDMS9zqrcAM5fg+RC2Gr3myB6ggMl4+J1CDU0G/8dm7PsAEKsLkqT4YsY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=fnZkILcE; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fnZkILcE" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772793446; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OZ1uxUMfdvEVIiXLLllIOCQX5Y7WK3c/GBbiTWtJcUU=; b=fnZkILcExJ8pgXy8ARNbW0urQwj3E9hEaq57RfM2MTyLjEAaFrcywR/hBKFSImgDPi+5/B B0Pl3qLfJdFslY64p5vuz3Rt0g4eCV+SHoEwrgwS5kjMJVxTA77dUrzVeI/YGT9V7g+Jm4 enuKaiTYyTVeVAKQ02Ba4K+IL5zu1RE= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-294-AAMy9kKQN4eRmXL4ZNJgAg-1; Fri, 06 Mar 2026 05:37:22 -0500 X-MC-Unique: AAMy9kKQN4eRmXL4ZNJgAg-1 X-Mimecast-MFC-AGG-ID: AAMy9kKQN4eRmXL4ZNJgAg_1772793440 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 43CE718005B9; Fri, 6 Mar 2026 10:37:20 +0000 (UTC) Received: from [192.168.1.153] (unknown [10.45.226.103]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7E1CA180058B; Fri, 6 Mar 2026 10:37:13 +0000 (UTC) From: Albert Esteve Date: Fri, 06 Mar 2026 11:36:33 +0100 Subject: [PATCH v3 2/6] dma-buf: dma-heap: split dma_heap_add Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260306-b4-dmabuf-heap-coherent-rmem-v3-2-3d00d36c9bc4@redhat.com> References: <20260306-b4-dmabuf-heap-coherent-rmem-v3-0-3d00d36c9bc4@redhat.com> In-Reply-To: <20260306-b4-dmabuf-heap-coherent-rmem-v3-0-3d00d36c9bc4@redhat.com> To: Sumit Semwal , Benjamin Gaignard , Brian Starkey , John Stultz , "T.J. Mercier" , =?utf-8?q?Christian_K=C3=B6nig?= , Marek Szyprowski , Robin Murphy , Rob Herring , Saravana Kannan Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, iommu@lists.linux.dev, devicetree@vger.kernel.org, Albert Esteve , mripard@redhat.com, echanude@redhat.com X-Developer-Signature: v=1; a=ed25519-sha256; t=1772793417; l=6927; i=aesteve@redhat.com; s=20260303; h=from:subject:message-id; bh=jnEWfPpzZhM9PT5/4IIyDdYQm5qsF5MEa9uiNa9/840=; b=Uq16kJks+H+M48RJxOWpGu8dbWraHuDz9VUhJlh3teNs+cTNDwHXuQtrqIYX0saef7gs9UfOD kjuetUfxw/5A+RGtAyaCBo6FmPDtCDuojyos6wX0xUOjdQR0OgL/nth X-Developer-Key: i=aesteve@redhat.com; a=ed25519; pk=YSFz6sOHd2L45+Fr8DIvHTi6lSIjhLZ5T+rkxspJt1s= X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Split dma_heap_add() into creation and registration phases while preserving the ordering between cdev_add() and device_add(), and ensuring all device fields are initialised. This lets callers build a heap and its device, bind reserved memory, and cleanly unwind on failure before the heap is registered. It also avoids a window where userspace can see a heap that exists but isn=E2=80=99t fully functional. The coherent heap will need this to bind rmem to the heap device prior to registration. Signed-off-by: Albert Esteve --- drivers/dma-buf/dma-heap.c | 126 +++++++++++++++++++++++++++++++++++------= ---- include/linux/dma-heap.h | 3 ++ 2 files changed, 103 insertions(+), 26 deletions(-) diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index 1124d63eb1398..ba87e5ac16ae2 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -238,15 +238,30 @@ struct device *dma_heap_get_dev(struct dma_heap *heap) } EXPORT_SYMBOL_NS_GPL(dma_heap_get_dev, "DMA_BUF_HEAP"); =20 +static void dma_heap_dev_release(struct device *dev) +{ + struct dma_heap *heap; + + pr_debug("heap device: '%s': %s\n", dev_name(dev), __func__); + heap =3D dev_get_drvdata(dev); + kfree(heap->name); + kfree(heap); + kfree(dev); +} + /** - * dma_heap_add - adds a heap to dmabuf heaps - * @exp_info: information needed to register this heap + * dma_heap_create() - allocate and initialize a heap object + * @exp_info: information needed to create a heap + * + * Creates a heap instance but does not register it or create device nodes. + * Use dma_heap_register() to make it visible to userspace, or + * dma_heap_destroy() to release it. + * + * Returns a heap on success or ERR_PTR(-errno) on failure. */ -struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) +struct dma_heap *dma_heap_create(const struct dma_heap_export_info *exp_in= fo) { - struct dma_heap *heap, *h, *err_ret; - unsigned int minor; - int ret; + struct dma_heap *heap; =20 if (!exp_info->name || !strcmp(exp_info->name, "")) { pr_err("dma_heap: Cannot add heap without a name\n"); @@ -265,13 +280,41 @@ struct dma_heap *dma_heap_add(const struct dma_heap_e= xport_info *exp_info) heap->name =3D exp_info->name; heap->ops =3D exp_info->ops; heap->priv =3D exp_info->priv; + heap->heap_dev =3D kzalloc_obj(*heap->heap_dev); + if (!heap->heap_dev) { + kfree(heap); + return ERR_PTR(-ENOMEM); + } + + device_initialize(heap->heap_dev); + dev_set_drvdata(heap->heap_dev, heap); + + dev_set_name(heap->heap_dev, heap->name); + heap->heap_dev->class =3D dma_heap_class; + heap->heap_dev->release =3D dma_heap_dev_release; + + return heap; +} +EXPORT_SYMBOL_NS_GPL(dma_heap_create, "DMA_BUF_HEAP"); + +/** + * dma_heap_register() - register a heap with the dma-heap framework + * @heap: heap instance created with dma_heap_create() + * + * Registers the heap, creating its device node and adding it to the heap + * list. Returns 0 on success or a negative error code on failure. + */ +int dma_heap_register(struct dma_heap *heap) +{ + struct dma_heap *h; + unsigned int minor; + int ret; =20 /* Find unused minor number */ ret =3D xa_alloc(&dma_heap_minors, &minor, heap, XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL); if (ret < 0) { pr_err("dma_heap: Unable to get minor number for heap\n"); - err_ret =3D ERR_PTR(ret); goto err0; } =20 @@ -282,42 +325,34 @@ struct dma_heap *dma_heap_add(const struct dma_heap_e= xport_info *exp_info) ret =3D cdev_add(&heap->heap_cdev, heap->heap_devt, 1); if (ret < 0) { pr_err("dma_heap: Unable to add char device\n"); - err_ret =3D ERR_PTR(ret); goto err1; } =20 - heap->heap_dev =3D device_create(dma_heap_class, - NULL, - heap->heap_devt, - NULL, - heap->name); - if (IS_ERR(heap->heap_dev)) { - pr_err("dma_heap: Unable to create device\n"); - err_ret =3D ERR_CAST(heap->heap_dev); + heap->heap_dev->devt =3D heap->heap_devt; + + ret =3D device_add(heap->heap_dev); + if (ret) { + pr_err("dma_heap: Unable to add device\n"); goto err2; } =20 mutex_lock(&heap_list_lock); /* check the name is unique */ list_for_each_entry(h, &heap_list, list) { - if (!strcmp(h->name, exp_info->name)) { + if (!strcmp(h->name, heap->name)) { mutex_unlock(&heap_list_lock); pr_err("dma_heap: Already registered heap named %s\n", - exp_info->name); - err_ret =3D ERR_PTR(-EINVAL); + heap->name); + ret =3D -EINVAL; goto err3; } } =20 - /* Make sure it doesn't disappear on us */ - heap->heap_dev =3D get_device(heap->heap_dev); - - /* Add heap to the list */ list_add(&heap->list, &heap_list); mutex_unlock(&heap_list_lock); =20 - return heap; + return 0; =20 err3: device_destroy(dma_heap_class, heap->heap_devt); @@ -326,8 +361,47 @@ struct dma_heap *dma_heap_add(const struct dma_heap_ex= port_info *exp_info) err1: xa_erase(&dma_heap_minors, minor); err0: - kfree(heap); - return err_ret; + dma_heap_destroy(heap); + return ret; +} +EXPORT_SYMBOL_NS_GPL(dma_heap_register, "DMA_BUF_HEAP"); + +/** + * dma_heap_destroy() - release a heap created by dma_heap_create() + * @heap: heap instance to release + * + * Drops the heap device reference; the heap and its device are freed in t= he + * device release path when the last reference is gone. + */ +void dma_heap_destroy(struct dma_heap *heap) +{ + put_device(heap->heap_dev); +} +EXPORT_SYMBOL_NS_GPL(dma_heap_destroy, "DMA_BUF_HEAP"); + +/** + * dma_heap_add - adds a heap to dmabuf heaps + * @exp_info: information needed to register this heap + */ +struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) +{ + struct dma_heap *heap; + int ret; + + heap =3D dma_heap_create(exp_info); + if (IS_ERR(heap)) { + pr_err("dma_heap: failed to create heap (%ld)\n", PTR_ERR(heap)); + return ERR_CAST(heap); + } + + ret =3D dma_heap_register(heap); + if (ret) { + pr_err("dma_heap: failed to register heap (%d)\n", ret); + dma_heap_destroy(heap); + return ERR_PTR(ret); + } + + return heap; } EXPORT_SYMBOL_NS_GPL(dma_heap_add, "DMA_BUF_HEAP"); =20 diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 493085e69b70e..1b0ea43ba66c3 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -46,6 +46,9 @@ void *dma_heap_get_drvdata(struct dma_heap *heap); const char *dma_heap_get_name(struct dma_heap *heap); struct device *dma_heap_get_dev(struct dma_heap *heap); =20 +struct dma_heap *dma_heap_create(const struct dma_heap_export_info *exp_in= fo); +int dma_heap_register(struct dma_heap *heap); +void dma_heap_destroy(struct dma_heap *heap); struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info); =20 extern bool mem_accounting; --=20 2.52.0