dma-buf: add some tracepoints to debug.

Since we can only inspect dmabuf by iterating over process FDs or the
dmabuf_list, we need to add our own tracepoints to track its status in
real time in production.

For example:
   binder:3016_1-3102    [006] ...1.   255.126521: dma_buf_export: exp_name=qcom,system size=12685312 ino=2738
   binder:3016_1-3102    [006] ...1.   255.126528: dma_buf_fd: exp_name=qcom,system size=12685312 ino=2738 fd=8
   binder:3016_1-3102    [006] ...1.   255.126642: dma_buf_mmap_internal: exp_name=qcom,system size=28672 ino=2739
     kworker/6:1-86      [006] ...1.   255.127194: dma_buf_put: exp_name=qcom,system size=12685312 ino=2738
    RenderThread-9293    [006] ...1.   316.618179: dma_buf_get: exp_name=qcom,system size=12771328 ino=2762 fd=176
    RenderThread-9293    [006] ...1.   316.618195: dma_buf_dynamic_attach: exp_name=qcom,system size=12771328 ino=2762 attachment:ffffff880a18dd00 is_dynamic=0 dev_name=kgsl-3d0
    RenderThread-9293    [006] ...1.   318.878220: dma_buf_detach: exp_name=qcom,system size=12771328 ino=2762 attachment:ffffff880a18dd00 is_dynamic=0 dev_name=kgsl-3d0

Signed-off-by: Xiang Gao <gaoxiang17@xiaomi.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20251218062853.819744-1-gxxa03070307@gmail.com
Signed-off-by: Christian König <christian.koenig@amd.com>

drivers/dma-buf/dma-buf.c

@@ -35,6 +35,28 @@
 
 #include "dma-buf-sysfs-stats.h"
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/dma_buf.h>
+
+/*
+ * dmabuf->name must be accessed with holding dmabuf->name_lock.
+ * we need to take the lock around the tracepoint call itself where
+ * it is called in the code.
+ *
+ * Note: FUNC##_enabled() is a static branch that will only
+ *       be set when the trace event is enabled.
+ */
+#define DMA_BUF_TRACE(FUNC, ...)					\
+	do {								\
+		if (FUNC##_enabled()) {					\
+			guard(spinlock)(&dmabuf->name_lock);		\
+			FUNC(__VA_ARGS__);				\
+		} else if (IS_ENABLED(CONFIG_LOCKDEP)) {		\
+			/* Expose this lock when lockdep is enabled */	\
+			guard(spinlock)(&dmabuf->name_lock);		\
+		}							\
+	} while (0)
+
 /* Wrapper to hide the sg_table page link from the importer */
 struct dma_buf_sg_table_wrapper {
 	struct sg_table *original;
@@ -226,6 +248,8 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 	    dmabuf->size >> PAGE_SHIFT)
 		return -EINVAL;
 
+	DMA_BUF_TRACE(trace_dma_buf_mmap_internal, dmabuf);
+
 	return dmabuf->ops->mmap(dmabuf, vma);
 }
 
@@ -751,6 +775,8 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 
 	__dma_buf_list_add(dmabuf);
 
+	DMA_BUF_TRACE(trace_dma_buf_export, dmabuf);
+
 	return dmabuf;
 
 err_dmabuf:
@@ -774,10 +800,16 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_export, "DMA_BUF");
  */
 int dma_buf_fd(struct dma_buf *dmabuf, int flags)
 {
+	int fd;
+
 	if (!dmabuf || !dmabuf->file)
 		return -EINVAL;
 
-	return FD_ADD(flags, dmabuf->file);
+	fd = FD_ADD(flags, dmabuf->file);
+	if (fd >= 0)
+		DMA_BUF_TRACE(trace_dma_buf_fd, dmabuf, fd);
+
+	return fd;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_fd, "DMA_BUF");
 
@@ -792,6 +824,7 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_fd, "DMA_BUF");
 struct dma_buf *dma_buf_get(int fd)
 {
 	struct file *file;
+	struct dma_buf *dmabuf;
 
 	file = fget(fd);
 
@@ -803,7 +836,11 @@ struct dma_buf *dma_buf_get(int fd)
 		return ERR_PTR(-EINVAL);
 	}
 
-	return file->private_data;
+	dmabuf = file->private_data;
+
+	DMA_BUF_TRACE(trace_dma_buf_get, dmabuf, fd);
+
+	return dmabuf;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_get, "DMA_BUF");
 
@@ -823,6 +860,8 @@ void dma_buf_put(struct dma_buf *dmabuf)
 		return;
 
 	fput(dmabuf->file);
+
+	DMA_BUF_TRACE(trace_dma_buf_put, dmabuf);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_put, "DMA_BUF");
 
@@ -1015,6 +1054,9 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
 	list_add(&attach->node, &dmabuf->attachments);
 	dma_resv_unlock(dmabuf->resv);
 
+	DMA_BUF_TRACE(trace_dma_buf_dynamic_attach, dmabuf, attach,
+		dma_buf_attachment_is_dynamic(attach), dev);
+
 	return attach;
 
 err_attach:
@@ -1059,6 +1101,9 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 	if (dmabuf->ops->detach)
 		dmabuf->ops->detach(dmabuf, attach);
 
+	DMA_BUF_TRACE(trace_dma_buf_detach, dmabuf, attach,
+		dma_buf_attachment_is_dynamic(attach), attach->dev);
+
 	kfree(attach);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_detach, "DMA_BUF");
@@ -1525,6 +1570,8 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 	vma_set_file(vma, dmabuf->file);
 	vma->vm_pgoff = pgoff;
 
+	DMA_BUF_TRACE(trace_dma_buf_mmap, dmabuf);
+
 	return dmabuf->ops->mmap(dmabuf, vma);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, "DMA_BUF");

include/trace/events/dma_buf.h

@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM dma_buf
+
+#if !defined(_TRACE_DMA_BUF_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_DMA_BUF_H
+
+#include <linux/dma-buf.h>
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(dma_buf,
+
+	TP_PROTO(struct dma_buf *dmabuf),
+
+	TP_ARGS(dmabuf),
+
+	TP_STRUCT__entry(
+		__string(exp_name, dmabuf->exp_name)
+		__field(size_t, size)
+		__field(ino_t, ino)
+	),
+
+	TP_fast_assign(
+		__assign_str(exp_name);
+		__entry->size = dmabuf->size;
+		__entry->ino = dmabuf->file->f_inode->i_ino;
+	),
+
+	TP_printk("exp_name=%s size=%zu ino=%lu",
+		  __get_str(exp_name),
+		  __entry->size,
+		  __entry->ino)
+);
+
+DECLARE_EVENT_CLASS(dma_buf_attach_dev,
+
+	TP_PROTO(struct dma_buf *dmabuf, struct dma_buf_attachment *attach,
+		bool is_dynamic, struct device *dev),
+
+	TP_ARGS(dmabuf, attach, is_dynamic, dev),
+
+	TP_STRUCT__entry(
+		__string(dev_name, dev_name(dev))
+		__string(exp_name, dmabuf->exp_name)
+		__field(size_t, size)
+		__field(ino_t, ino)
+		__field(struct dma_buf_attachment *, attach)
+		__field(bool, is_dynamic)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev_name);
+		__assign_str(exp_name);
+		__entry->size = dmabuf->size;
+		__entry->ino = dmabuf->file->f_inode->i_ino;
+		__entry->is_dynamic = is_dynamic;
+		__entry->attach = attach;
+	),
+
+	TP_printk("exp_name=%s size=%zu ino=%lu attachment:%p is_dynamic=%d dev_name=%s",
+		  __get_str(exp_name),
+		  __entry->size,
+		  __entry->ino,
+		  __entry->attach,
+		  __entry->is_dynamic,
+		  __get_str(dev_name))
+);
+
+DECLARE_EVENT_CLASS(dma_buf_fd,
+
+	TP_PROTO(struct dma_buf *dmabuf, int fd),
+
+	TP_ARGS(dmabuf, fd),
+
+	TP_STRUCT__entry(
+		__string(exp_name, dmabuf->exp_name)
+		__field(size_t, size)
+		__field(ino_t, ino)
+		__field(int, fd)
+	),
+
+	TP_fast_assign(
+		__assign_str(exp_name);
+		__entry->size = dmabuf->size;
+		__entry->ino = dmabuf->file->f_inode->i_ino;
+		__entry->fd = fd;
+	),
+
+	TP_printk("exp_name=%s size=%zu ino=%lu fd=%d",
+		  __get_str(exp_name),
+		  __entry->size,
+		  __entry->ino,
+		  __entry->fd)
+);
+
+DEFINE_EVENT(dma_buf, dma_buf_export,
+
+	TP_PROTO(struct dma_buf *dmabuf),
+
+	TP_ARGS(dmabuf)
+);
+
+DEFINE_EVENT(dma_buf, dma_buf_mmap_internal,
+
+	TP_PROTO(struct dma_buf *dmabuf),
+
+	TP_ARGS(dmabuf)
+);
+
+DEFINE_EVENT(dma_buf, dma_buf_mmap,
+
+	TP_PROTO(struct dma_buf *dmabuf),
+
+	TP_ARGS(dmabuf)
+);
+
+DEFINE_EVENT(dma_buf, dma_buf_put,
+
+	TP_PROTO(struct dma_buf *dmabuf),
+
+	TP_ARGS(dmabuf)
+);
+
+DEFINE_EVENT(dma_buf_attach_dev, dma_buf_dynamic_attach,
+
+	TP_PROTO(struct dma_buf *dmabuf, struct dma_buf_attachment *attach,
+		bool is_dynamic, struct device *dev),
+
+	TP_ARGS(dmabuf, attach, is_dynamic, dev)
+);
+
+DEFINE_EVENT(dma_buf_attach_dev, dma_buf_detach,
+
+	TP_PROTO(struct dma_buf *dmabuf, struct dma_buf_attachment *attach,
+		bool is_dynamic, struct device *dev),
+
+	TP_ARGS(dmabuf, attach, is_dynamic, dev)
+);
+
+DEFINE_EVENT(dma_buf_fd, dma_buf_fd,
+
+	TP_PROTO(struct dma_buf *dmabuf, int fd),
+
+	TP_ARGS(dmabuf, fd)
+);
+
+DEFINE_EVENT(dma_buf_fd, dma_buf_get,
+
+	TP_PROTO(struct dma_buf *dmabuf, int fd),
+
+	TP_ARGS(dmabuf, fd)
+);
+
+#endif /* _TRACE_DMA_BUF_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>