From 49af2e35d5e7aff15c3bb47482ec34f69cba7bc8 Mon Sep 17 00:00:00 2001
From: Guangming Cao <Guangming.Cao@mediatek.com>
Date: Wed, 1 Sep 2021 20:41:54 +0800
Subject: [PATCH] FROMLIST: dma-buf: support users to change dma_buf.name

User space user can call DMA_BUF_SET_NAME to set dma_buf.name,
but until now we can't set it at kernel side, it's difficult to debug
kernel dma_buf users.

There are some kernel users of dma_heap also need it at MTK,
such as camera, it's also have a allocator for other camera part,
unlike most case in userspace, it's in kernel.
For debug buffer owner, we need add it to let it can set debug name
for each dmabuf, so that we can know dmabuf owner by dma_buf.name.

Bug: 193623372
Link: https://lore.kernel.org/patchwork/patch/1459719/
Change-Id: Iac5c6b8838b9b4d976f4525d000e17a3abab94f6
Signed-off-by: Guangming Cao <Guangming.Cao@mediatek.com>
---
 drivers/dma-buf/dma-buf.c | 52 +++++++++++++++++++++++++++++----------
 include/linux/dma-buf.h   |  1 +
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index d9948d58b3f4..0ee38382ba17 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -348,6 +348,25 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
 	return events;
 }
 
+static long _dma_buf_set_name(struct dma_buf *dmabuf, const char *name)
+{
+	long ret = 0;
+
+	dma_resv_lock(dmabuf->resv, NULL);
+	if (!list_empty(&dmabuf->attachments)) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	spin_lock(&dmabuf->name_lock);
+	kfree(dmabuf->name);
+	dmabuf->name = name;
+	spin_unlock(&dmabuf->name_lock);
+
+out_unlock:
+	dma_resv_unlock(dmabuf->resv);
+	return ret;
+}
+
 /**
  * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
  * The name of the dma-buf buffer can only be set when the dma-buf is not
@@ -363,7 +382,23 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
  * devices, return -EBUSY.
  *
  */
-static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
+long dma_buf_set_name(struct dma_buf *dmabuf, const char *name)
+{
+	long ret = 0;
+	char *buf = kstrndup(name, DMA_BUF_NAME_LEN, GFP_KERNEL);
+
+	if (!buf)
+		return -ENOMEM;
+
+	ret = _dma_buf_set_name(dmabuf, buf);
+	if (ret)
+		kfree(buf);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dma_buf_set_name);
+
+static long dma_buf_set_name_user(struct dma_buf *dmabuf, const char __user *buf)
 {
 	char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
 	long ret = 0;
@@ -371,19 +406,10 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
 	if (IS_ERR(name))
 		return PTR_ERR(name);
 
-	dma_resv_lock(dmabuf->resv, NULL);
-	if (!list_empty(&dmabuf->attachments)) {
-		ret = -EBUSY;
+	ret = _dma_buf_set_name(dmabuf, name);
+	if (ret)
 		kfree(name);
-		goto out_unlock;
-	}
-	spin_lock(&dmabuf->name_lock);
-	kfree(dmabuf->name);
-	dmabuf->name = name;
-	spin_unlock(&dmabuf->name_lock);
 
-out_unlock:
-	dma_resv_unlock(dmabuf->resv);
 	return ret;
 }
 
@@ -428,7 +454,7 @@ static long dma_buf_ioctl(struct file *file,
 
 	case DMA_BUF_SET_NAME_A:
 	case DMA_BUF_SET_NAME_B:
-		return dma_buf_set_name(dmabuf, (const char __user *)arg);
+		return dma_buf_set_name_user(dmabuf, (const char __user *)arg);
 
 	default:
 		return -ENOTTY;
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 63ffe57a61d5..a9ad8cfdd8fd 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -623,6 +623,7 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
 		 unsigned long);
 void *dma_buf_vmap(struct dma_buf *);
 void dma_buf_vunmap(struct dma_buf *, void *vaddr);
+long dma_buf_set_name(struct dma_buf *dmabuf, const char *name);
 int dma_buf_get_flags(struct dma_buf *dmabuf, unsigned long *flags);
 int dma_buf_get_uuid(struct dma_buf *dmabuf, uuid_t *uuid);