Re: [PATCH v8] dma-buf: add some tracepoints to debug.

["Christian König" <christian.koenig@amd.com>]

On 12/18/25 07:28, Xiang Gao wrote:
> From: gaoxiang17 <gaoxiang17@xiaomi.com>
> 
> 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>

This patch was still not properly rebased on drm-misc-next and there was some whitespace issues with the macro.

I've reviewed the patch, fixed the merge conflict and whitespace issues and pushed the result to drm-misc-next.

Thanks,
Christian.

> ---
>  drivers/dma-buf/dma-buf.c      |  51 ++++++++++-
>  include/trace/events/dma_buf.h | 157 +++++++++++++++++++++++++++++++++
>  2 files changed, 206 insertions(+), 2 deletions(-)
>  create mode 100644 include/trace/events/dma_buf.h
> 
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index edaa9e4ee4ae..59a5261cb26b 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/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)
> +
>  static inline int is_dma_buf_file(struct file *);
>  
>  static DEFINE_MUTEX(dmabuf_list_mutex);
> @@ -220,6 +242,8 @@ 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);
>  }
>  
> @@ -745,6 +769,8 @@ 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:
> @@ -768,10 +794,16 @@ 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");
>  
> @@ -786,6 +818,7 @@ 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);
>  
> @@ -797,7 +830,11 @@ 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");
>  
> @@ -817,6 +854,8 @@ 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");
>  
> @@ -971,6 +1010,9 @@ 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:
> @@ -1015,6 +1057,9 @@ 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");
> @@ -1480,6 +1525,8 @@ 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");
> diff --git a/include/trace/events/dma_buf.h b/include/trace/events/dma_buf.h
> new file mode 100644
> index 000000000000..35f8140095f4
> --- /dev/null
> +++ b/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>