[RFC PATCH 27/60] hyper_dmabuf: use proper error codes

[Dongwon Kim]

Cleaned up and corrected error codes and condition in various
error check routines. Also added proper err messages when func
returns error.

Signed-off-by: Dongwon Kim <dongwon.kim@xxxxxxxxx>
---
 drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c        | 14 +++--
 drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c         |  2 +-
 drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c        |  8 +--
 drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c      | 66 ++++++++++++++--------
 drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c       |  6 +-
 drivers/xen/hyper_dmabuf/hyper_dmabuf_msg.c        |  5 +-
 .../xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c    | 38 ++++++-------
 .../xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm.c   | 20 +++----
 .../hyper_dmabuf/xen/hyper_dmabuf_xen_comm_list.c  |  4 +-
 .../xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c    |  2 +-
 10 files changed, 94 insertions(+), 71 deletions(-)

diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
index 584d55d..44a9139 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
@@ -60,7 +60,7 @@ static int __init hyper_dmabuf_drv_init(void)
 
 	ret = register_device();
 	if (ret < 0) {
-		return -EINVAL;
+		return ret;
 	}
 
 #ifdef CONFIG_HYPER_DMABUF_XEN
@@ -77,18 +77,24 @@ static int __init hyper_dmabuf_drv_init(void)
 
 	ret = hyper_dmabuf_table_init();
 	if (ret < 0) {
-		return -EINVAL;
+		dev_err(hyper_dmabuf_private.device,
+			"failed to initialize table for exported/imported entries\n");
+		return ret;
 	}
 
 	ret = hyper_dmabuf_private.backend_ops->init_comm_env();
 	if (ret < 0) {
-		return -EINVAL;
+		dev_err(hyper_dmabuf_private.device,
+			"failed to initiailize hypervisor-specific comm env\n");
+		return ret;
 	}
 
 #ifdef CONFIG_HYPER_DMABUF_SYSFS
 	ret = hyper_dmabuf_register_sysfs(hyper_dmabuf_private.device);
 	if (ret < 0) {
-		return -EINVAL;
+		dev_err(hyper_dmabuf_private.device,
+			"failed to initialize sysfs\n");
+		return ret;
 	}
 #endif
 
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c
index 9b4ff45..35bfdfb 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c
@@ -62,7 +62,7 @@ static int retrieve_reusable_id(void)
 		return id;
 	}
 
-	return -1;
+	return -ENOENT;
 }
 
 void destroy_reusable_list(void)
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
index a9bc354..a0b3946 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
@@ -84,11 +84,11 @@ struct hyper_dmabuf_pages_info *hyper_dmabuf_ext_pgs(struct sg_table *sgt)
 	struct scatterlist *sgl;
 
 	pinfo = kmalloc(sizeof(*pinfo), GFP_KERNEL);
-	if (pinfo == NULL)
+	if (!pinfo)
 		return NULL;
 
 	pinfo->pages = kmalloc(sizeof(struct page *)*hyper_dmabuf_get_num_pgs(sgt), GFP_KERNEL);
-	if (pinfo->pages == NULL)
+	if (!pinfo->pages)
 		return NULL;
 
 	sgl = sgt->sgl;
@@ -138,7 +138,7 @@ struct sg_table* hyper_dmabuf_create_sgt(struct page **pages,
 	int i, ret;
 
 	sgt = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
-	if (sgt == NULL) {
+	if (!sgt) {
 		return NULL;
 	}
 
@@ -348,7 +348,7 @@ static struct sg_table* hyper_dmabuf_ops_map(struct dma_buf_attachment *attachme
 	/* create a new sg_table with extracted pages */
 	st = hyper_dmabuf_create_sgt(page_info->pages, page_info->frst_ofst,
 				page_info->last_len, page_info->nents);
-	if (st == NULL)
+	if (!st)
 		goto err_free_sg;
 
         if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) {
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
index 8851a9c..19ca725 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
@@ -54,7 +54,7 @@ static int hyper_dmabuf_tx_ch_setup(void *data)
 
 	if (!data) {
 		dev_err(hyper_dmabuf_private.device, "user data is NULL\n");
-		return -1;
+		return -EINVAL;
 	}
 	tx_ch_attr = (struct ioctl_hyper_dmabuf_tx_ch_setup *)data;
 
@@ -71,7 +71,7 @@ static int hyper_dmabuf_rx_ch_setup(void *data)
 
 	if (!data) {
 		dev_err(hyper_dmabuf_private.device, "user data is NULL\n");
-		return -1;
+		return -EINVAL;
 	}
 
 	rx_ch_attr = (struct ioctl_hyper_dmabuf_rx_ch_setup *)data;
@@ -96,16 +96,16 @@ static int hyper_dmabuf_export_remote(void *data)
 
 	if (!data) {
 		dev_err(hyper_dmabuf_private.device, "user data is NULL\n");
-		return -1;
+		return -EINVAL;
 	}
 
 	export_remote_attr = (struct ioctl_hyper_dmabuf_export_remote *)data;
 
 	dma_buf = dma_buf_get(export_remote_attr->dmabuf_fd);
 
-	if (!dma_buf) {
+	if (IS_ERR(dma_buf)) {
 		dev_err(hyper_dmabuf_private.device,  "Cannot get dma buf\n");
-		return -1;
+		return PTR_ERR(dma_buf);
 	}
 
 	/* we check if this specific attachment was already exported
@@ -114,7 +114,7 @@ static int hyper_dmabuf_export_remote(void *data)
 	 */
 	ret = hyper_dmabuf_find_id_exported(dma_buf, export_remote_attr->remote_domain);
 	sgt_info = hyper_dmabuf_find_exported(ret);
-	if (ret != -1 && sgt_info->valid) {
+	if (ret != -ENOENT && sgt_info->valid) {
 		/*
 		 * Check if unexport is already scheduled for that buffer,
 		 * if so try to cancel it. If that will fail, buffer needs
@@ -134,9 +134,9 @@ static int hyper_dmabuf_export_remote(void *data)
 
 reexport:
 	attachment = dma_buf_attach(dma_buf, hyper_dmabuf_private.device);
-	if (!attachment) {
+	if (IS_ERR(attachment)) {
 		dev_err(hyper_dmabuf_private.device, "Cannot get attachment\n");
-		return -1;
+		return PTR_ERR(attachment);
 	}
 
 	/* Clear ret, as that will cause whole ioctl to return failure
@@ -148,6 +148,11 @@ static int hyper_dmabuf_export_remote(void *data)
 
 	sgt_info = kcalloc(1, sizeof(*sgt_info), GFP_KERNEL);
 
+	if(!sgt_info) {
+		dev_err(hyper_dmabuf_private.device, "no more space left\n");
+		return -ENOMEM;
+	}
+
 	sgt_info->hyper_dmabuf_id = hyper_dmabuf_get_id();
 
 	/* TODO: We might need to consider using port number on event channel? */
@@ -174,8 +179,10 @@ static int hyper_dmabuf_export_remote(void *data)
 	INIT_LIST_HEAD(&sgt_info->va_vmapped->list);
 
 	page_info = hyper_dmabuf_ext_pgs(sgt);
-	if (page_info == NULL)
+	if (!page_info) {
+		dev_err(hyper_dmabuf_private.device, "failed to construct page_info\n");
 		goto fail_export;
+	}
 
 	sgt_info->nents = page_info->nents;
 
@@ -206,8 +213,12 @@ static int hyper_dmabuf_export_remote(void *data)
 	/* composing a message to the importer */
 	hyper_dmabuf_create_request(req, HYPER_DMABUF_EXPORT, &operands[0]);
 
-	if(ops->send_req(export_remote_attr->remote_domain, req, false))
+	ret = ops->send_req(export_remote_attr->remote_domain, req, false);
+
+	if(ret) {
+		dev_err(hyper_dmabuf_private.device, "error while communicating\n");
 		goto fail_send_request;
+	}
 
 	/* free msg */
 	kfree(req);
@@ -233,7 +244,7 @@ static int hyper_dmabuf_export_remote(void *data)
 	kfree(sgt_info->va_kmapped);
 	kfree(sgt_info->va_vmapped);
 
-	return -EINVAL;
+	return ret;
 }
 
 static int hyper_dmabuf_export_fd_ioctl(void *data)
@@ -257,8 +268,12 @@ static int hyper_dmabuf_export_fd_ioctl(void *data)
 
 	/* look for dmabuf for the id */
 	sgt_info = hyper_dmabuf_find_imported(export_fd_attr->hyper_dmabuf_id);
-	if (sgt_info == NULL || !sgt_info->valid) /* can't find sgt from the table */
-		return -1;
+
+	/* can't find sgt from the table */
+	if (!sgt_info) {
+		dev_err(hyper_dmabuf_private.device, "can't find the entry\n");
+		return -ENOENT;
+	}
 
 	mutex_lock(&hyper_dmabuf_private.lock);
 
@@ -277,7 +292,7 @@ static int hyper_dmabuf_export_fd_ioctl(void *data)
 		dev_err(hyper_dmabuf_private.device, "Failed to create sgt or notify exporter\n");
 		sgt_info->num_importers--;
 		mutex_unlock(&hyper_dmabuf_private.lock);
-		return -EINVAL;
+		return ret;
 	}
 	kfree(req);
 
@@ -286,9 +301,10 @@ static int hyper_dmabuf_export_fd_ioctl(void *data)
 			"Buffer invalid\n");
 		sgt_info->num_importers--;
 		mutex_unlock(&hyper_dmabuf_private.lock);
-		return -1;
+		return -EINVAL;
 	} else {
 		dev_dbg(hyper_dmabuf_private.device, "Can import buffer\n");
+		ret = 0;
 	}
 
 	dev_dbg(hyper_dmabuf_private.device,
@@ -325,7 +341,7 @@ static int hyper_dmabuf_export_fd_ioctl(void *data)
 
 	mutex_unlock(&hyper_dmabuf_private.lock);
 	dev_dbg(hyper_dmabuf_private.device, "%s exit\n", __func__);
-	return 0;
+	return ret;
 }
 
 /* unexport dmabuf from the database and send int req to the source domain
@@ -405,8 +421,8 @@ static int hyper_dmabuf_unexport(void *data)
 
 	/* failed to find corresponding entry in export list */
 	if (sgt_info == NULL) {
-		unexport_attr->status = -EINVAL;
-		return -EFAULT;
+		unexport_attr->status = -ENOENT;
+		return -ENOENT;
 	}
 
 	if (sgt_info->unexport_scheduled)
@@ -441,7 +457,7 @@ static int hyper_dmabuf_query(void *data)
 	/* if dmabuf can't be found in both lists, return */
 	if (!(sgt_info && imported_sgt_info)) {
 		dev_err(hyper_dmabuf_private.device, "can't find entry anywhere\n");
-		return -EINVAL;
+		return -ENOENT;
 	}
 
 	/* not considering the case where a dmabuf is found on both queues
@@ -507,7 +523,7 @@ static long hyper_dmabuf_ioctl(struct file *filp,
 {
 	const struct hyper_dmabuf_ioctl_desc *ioctl = NULL;
 	unsigned int nr = _IOC_NR(cmd);
-	int ret = -EINVAL;
+	int ret;
 	hyper_dmabuf_ioctl_t func;
 	char *kdata;
 
@@ -565,13 +581,13 @@ static const char device_name[] = "hyper_dmabuf";
 /*===============================================================================================*/
 int register_device(void)
 {
-	int result = 0;
+	int ret = 0;
 
-	result = misc_register(&hyper_dmabuf_miscdev);
+	ret = misc_register(&hyper_dmabuf_miscdev);
 
-	if (result != 0) {
+	if (ret) {
 		printk(KERN_WARNING "hyper_dmabuf: driver can't be registered\n");
-		return result;
+		return ret;
 	}
 
 	hyper_dmabuf_private.device = hyper_dmabuf_miscdev.this_device;
@@ -589,7 +605,7 @@ int register_device(void)
 
 	info.irq = err;
 */
-	return result;
+	return ret;
 }
 
 /*-----------------------------------------------------------------------------------------------*/
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c
index e46ae19..2cb4bb4 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c
@@ -177,7 +177,7 @@ int hyper_dmabuf_find_id_exported(struct dma_buf *dmabuf, int domid)
 		   info_entry->info->hyper_dmabuf_rdomain == domid)
 			return info_entry->info->hyper_dmabuf_id;
 
-	return -1;
+	return -ENOENT;
 }
 
 struct hyper_dmabuf_imported_sgt_info *hyper_dmabuf_find_imported(int id)
@@ -204,7 +204,7 @@ int hyper_dmabuf_remove_exported(int id)
 			return 0;
 		}
 
-	return -1;
+	return -ENOENT;
 }
 
 int hyper_dmabuf_remove_imported(int id)
@@ -219,5 +219,5 @@ int hyper_dmabuf_remove_imported(int id)
 			return 0;
 		}
 
-	return -1;
+	return -ENOENT;
 }
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_msg.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_msg.c
index dd4bb01..6e24442 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_msg.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_msg.c
@@ -100,7 +100,7 @@ void hyper_dmabuf_create_request(struct hyper_dmabuf_req *req,
 		 * operands0 : hyper_dmabuf_id
 		 * operands1 : map(=1)/unmap(=2)/attach(=3)/detach(=4)
 		 */
-		for (i=0; i<2; i++)
+		for (i = 0; i < 2; i++)
 			req->operands[i] = operands[i];
 		break;
 
@@ -199,6 +199,7 @@ int hyper_dmabuf_msg_parse(int domid, struct hyper_dmabuf_req *req)
 		 */
 		dev_dbg(hyper_dmabuf_private.device,
 			"%s: processing HYPER_DMABUF_NOTIFY_UNEXPORT\n", __func__);
+
 		sgt_info = hyper_dmabuf_find_imported(req->operands[0]);
 
 		if (sgt_info) {
@@ -232,6 +233,7 @@ int hyper_dmabuf_msg_parse(int domid, struct hyper_dmabuf_req *req)
 		 */
 		dev_dbg(hyper_dmabuf_private.device,
 			"%s: HYPER_DMABUF_OPS_TO_SOURCE\n", __func__);
+
 		ret = hyper_dmabuf_remote_sync(req->operands[0], req->operands[1]);
 		if (ret)
 			req->status = HYPER_DMABUF_REQ_ERROR;
@@ -271,7 +273,6 @@ int hyper_dmabuf_msg_parse(int domid, struct hyper_dmabuf_req *req)
 	memcpy(temp_req, req, sizeof(*temp_req));
 
 	proc = kcalloc(1, sizeof(struct cmd_process), GFP_KERNEL);
-
 	proc->rq = temp_req;
 	proc->domid = domid;
 
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
index f93c936..a74e800 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
@@ -71,7 +71,7 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 	if (!sgt_info) {
 		dev_err(hyper_dmabuf_private.device,
 			"dmabuf remote sync::can't find exported list\n");
-		return -EINVAL;
+		return -ENOENT;
 	}
 
 	switch (ops) {
@@ -85,7 +85,7 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 			kfree(attachl);
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_ATTACH\n");
-			return -EINVAL;
+			return PTR_ERR(attachl->attach);
 		}
 
 		list_add(&attachl->list, &sgt_info->active_attached->list);
@@ -97,7 +97,7 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_DETACH\n");
 			dev_err(hyper_dmabuf_private.device,
 				"no more dmabuf attachment left to be detached\n");
-			return -EINVAL;
+			return -EFAULT;
 		}
 
 		attachl = list_first_entry(&sgt_info->active_attached->list,
@@ -113,8 +113,8 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_MAP\n");
 			dev_err(hyper_dmabuf_private.device,
-				"no more dmabuf attachment left to be detached\n");
-			return -EINVAL;
+				"no more dmabuf attachment left to be mapped\n");
+			return -EFAULT;
 		}
 
 		attachl = list_first_entry(&sgt_info->active_attached->list,
@@ -126,7 +126,7 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 			kfree(sgtl);
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_MAP\n");
-			return -EINVAL;
+			return PTR_ERR(sgtl->sgt);
 		}
 		list_add(&sgtl->list, &sgt_info->active_sgts->list);
 		break;
@@ -137,8 +137,8 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_UNMAP\n");
 			dev_err(hyper_dmabuf_private.device,
-				"no more SGT or attachment left to be freed\n");
-			return -EINVAL;
+				"no more SGT or attachment left to be unmapped\n");
+			return -EFAULT;
 		}
 
 		attachl = list_first_entry(&sgt_info->active_attached->list,
@@ -176,19 +176,19 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 
 	case HYPER_DMABUF_OPS_BEGIN_CPU_ACCESS:
 		ret = dma_buf_begin_cpu_access(sgt_info->dma_buf, DMA_BIDIRECTIONAL);
-		if (!ret) {
+		if (ret) {
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_BEGIN_CPU_ACCESS\n");
-			ret = -EINVAL;
+			return ret;
 		}
 		break;
 
 	case HYPER_DMABUF_OPS_END_CPU_ACCESS:
 		ret = dma_buf_end_cpu_access(sgt_info->dma_buf, DMA_BIDIRECTIONAL);
-		if (!ret) {
+		if (ret) {
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_END_CPU_ACCESS\n");
-			ret = -EINVAL;
+			return ret;
 		}
 		break;
 
@@ -206,7 +206,7 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 			kfree(va_kmapl);
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_KMAP(_ATOMIC)\n");
-			return -EINVAL;
+			return PTR_ERR(va_kmapl->vaddr);
 		}
 		list_add(&va_kmapl->list, &sgt_info->va_kmapped->list);
 		break;
@@ -218,15 +218,15 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_KUNMAP(_ATOMIC)\n");
 			dev_err(hyper_dmabuf_private.device,
 				"no more dmabuf VA to be freed\n");
-			return -EINVAL;
+			return -EFAULT;
 		}
 
 		va_kmapl = list_first_entry(&sgt_info->va_kmapped->list,
 					    struct kmap_vaddr_list, list);
-		if (va_kmapl->vaddr == NULL) {
+		if (!va_kmapl->vaddr) {
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_KUNMAP(_ATOMIC)\n");
-			return -EINVAL;
+			return PTR_ERR(va_kmapl->vaddr);
 		}
 
 		/* unmapping 1 page */
@@ -256,7 +256,7 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 			kfree(va_vmapl);
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_VMAP\n");
-			return -EINVAL;
+			return PTR_ERR(va_vmapl->vaddr);
 		}
 		list_add(&va_vmapl->list, &sgt_info->va_vmapped->list);
 		break;
@@ -267,14 +267,14 @@ int hyper_dmabuf_remote_sync(int id, int ops)
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_VUNMAP\n");
 			dev_err(hyper_dmabuf_private.device,
 				"no more dmabuf VA to be freed\n");
-			return -EINVAL;
+			return -EFAULT;
 		}
 		va_vmapl = list_first_entry(&sgt_info->va_vmapped->list,
 					struct vmap_vaddr_list, list);
 		if (!va_vmapl || va_vmapl->vaddr == NULL) {
 			dev_err(hyper_dmabuf_private.device,
 				"dmabuf remote sync::error while processing HYPER_DMABUF_OPS_VUNMAP\n");
-			return -EINVAL;
+			return -EFAULT;
 		}
 
 		dma_buf_vunmap(sgt_info->dma_buf, va_vmapl->vaddr);
diff --git a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm.c b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm.c
index 9d67b47..2cc35e3 100644
--- a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm.c
+++ b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm.c
@@ -232,7 +232,7 @@ int hyper_dmabuf_xen_init_tx_rbuf(int domid)
 	/* from exporter to importer */
 	shared_ring = (void *)__get_free_pages(GFP_KERNEL, 1);
 	if (shared_ring == 0) {
-		return -EINVAL;
+		return -ENOMEM;
 	}
 
 	sring = (struct xen_comm_sring *) shared_ring;
@@ -246,17 +246,17 @@ int hyper_dmabuf_xen_init_tx_rbuf(int domid)
 							   0);
 	if (ring_info->gref_ring < 0) {
 		/* fail to get gref */
-		return -EINVAL;
+		return -EFAULT;
 	}
 
 	alloc_unbound.dom = DOMID_SELF;
 	alloc_unbound.remote_dom = domid;
 	ret = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 					&alloc_unbound);
-	if (ret != 0) {
+	if (ret) {
 		dev_err(hyper_dmabuf_private.device,
 			"Cannot allocate event channel\n");
-		return -EINVAL;
+		return -EIO;
 	}
 
 	/* setting up interrupt */
@@ -271,7 +271,7 @@ int hyper_dmabuf_xen_init_tx_rbuf(int domid)
 		HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
 		gnttab_end_foreign_access(ring_info->gref_ring, 0,
 					virt_to_mfn(shared_ring));
-		return -EINVAL;
+		return -EIO;
 	}
 
 	ring_info->rdomain = domid;
@@ -387,7 +387,7 @@ int hyper_dmabuf_xen_init_rx_rbuf(int domid)
 	map_ops = kmalloc(sizeof(*map_ops), GFP_KERNEL);
 
 	if (gnttab_alloc_pages(1, &shared_ring)) {
-		return -EINVAL;
+		return -ENOMEM;
 	}
 
 	gnttab_set_map_op(&map_ops[0], (unsigned long)pfn_to_kaddr(page_to_pfn(shared_ring)),
@@ -399,12 +399,12 @@ int hyper_dmabuf_xen_init_rx_rbuf(int domid)
 	ret = gnttab_map_refs(map_ops, NULL, &shared_ring, 1);
 	if (ret < 0) {
 		dev_err(hyper_dmabuf_private.device, "Cannot map ring\n");
-		return -EINVAL;
+		return -EFAULT;
 	}
 
 	if (map_ops[0].status) {
 		dev_err(hyper_dmabuf_private.device, "Ring mapping failed\n");
-		return -EINVAL;
+		return -EFAULT;
 	} else {
 		ring_info->unmap_op.handle = map_ops[0].handle;
 	}
@@ -418,7 +418,7 @@ int hyper_dmabuf_xen_init_rx_rbuf(int domid)
 	ret = bind_interdomain_evtchn_to_irq(domid, rx_port);
 
 	if (ret < 0) {
-		return -EINVAL;
+		return -EIO;
 	}
 
 	ring_info->irq = ret;
@@ -511,7 +511,7 @@ int hyper_dmabuf_xen_send_req(int domid, struct hyper_dmabuf_req *req, int wait)
 	if (!ring_info) {
 		dev_err(hyper_dmabuf_private.device,
 			"Can't find ring info for the channel\n");
-		return -EINVAL;
+		return -ENOENT;
 	}
 
 
diff --git a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm_list.c b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm_list.c
index 0fa2d55..2f469da 100644
--- a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm_list.c
+++ b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_comm_list.c
@@ -110,7 +110,7 @@ int xen_comm_remove_tx_ring(int domid)
 			return 0;
 		}
 
-	return -1;
+	return -ENOENT;
 }
 
 int xen_comm_remove_rx_ring(int domid)
@@ -125,7 +125,7 @@ int xen_comm_remove_rx_ring(int domid)
 			return 0;
 		}
 
-	return -1;
+	return -ENOENT;
 }
 
 void xen_comm_foreach_tx_ring(void (*func)(int domid))
diff --git a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
index b158c11..c03e5a0 100644
--- a/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
+++ b/drivers/xen/hyper_dmabuf/xen/hyper_dmabuf_xen_shm.c
@@ -388,7 +388,7 @@ int hyper_dmabuf_xen_unmap_shared_pages(void **refs_info, int nents) {
 	if (gnttab_unmap_refs(sh_pages_info->unmap_ops, NULL,
 			      sh_pages_info->data_pages, nents) ) {
 		dev_err(hyper_dmabuf_private.device, "Cannot unmap data pages\n");
-		return -EINVAL;
+		return -EFAULT;
 	}
 
 	gnttab_free_pages(nents, sh_pages_info->data_pages);
-- 
2.7.4