答复: [External Mail]Re: [PATCH v3] dma-buf: add some tracepoints to debug.

[高翔 <gaoxiang17@xiaomi.com>]

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> Exporting the tracepoints is unecessary as far as I can see

android must export symbols before adding a whitelist.


> I can't come up with a reason why we should have the file refcount in the trace logs.
> Same for most other places.
I can directly observe how refcnt is changing.  Then it can be known where the dmabuf was finally released.


> Print the dev_name last, it's the external device which attaches to the DMA-buf.
ok.


> Additional to that it would be nice to know if the attachment is dynamic or not.
ok.


________________________________
发件人: Christian König <christian.koenig@amd.com>
发送时间: 2025年11月27日 17:49:09
收件人: Xiang Gao; sumit.semwal@linaro.org; rostedt@goodmis.org; mhiramat@kernel.org
抄送: linux-media@vger.kernel.org; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org; mathieu.desnoyers@efficios.com; dhowells@redhat.com; kuba@kernel.org; brauner@kernel.org; akpm@linux-foundation.org; linux-trace-kernel@vger.kernel.org; 高翔
主题: [External Mail]Re: [PATCH v3] dma-buf: add some tracepoints to debug.

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On 11/27/25 01:43, Xiang Gao wrote:
> From: gaoxiang17 <gaoxiang17@xiaomi.com>
>
> I want to track the status of dmabuf in real time in the production environment.
> But now we can only check it by traversing the fd in the process or dmabuf_list.
>
> For example:
>    binder:2962_2-2962    [005] ...1.   208.453940: dma_buf_export: exp_name=qcom,system name=(null) size=28672 ino=2580 f_refcnt=2
>    binder:2962_2-2962    [005] ...1.   208.453943: dma_buf_fd: exp_name=qcom,system name=(null) size=28672 ino=2580 fd=9 f_refcnt=2
>    binder:2962_2-2962    [005] ...1.   208.453977: dma_buf_mmap_internal: exp_name=qcom,system name=qcom,system size=28672 ino=2580 f_refcnt=4
>      kworker/5:2-194     [005] ...1.   208.460580: dma_buf_put: exp_name=qcom,system name=ab pid [8176] size=28672 ino=2580 f_refcnt=3
>     RenderThread-11305   [007] ...1.   208.599094: dma_buf_get: exp_name=qcom,system name=ab pid [8176] size=217088 ino=2579 fd=1114 f_refcnt=7
>     RenderThread-11305   [007] ...1.   208.599098: dma_buf_attach: dev_name=kgsl-3d0 exp_name=qcom,system name=ab pid [8176] size=217088 ino=2579 f_refcnt=7
>            <...>-14      [001] ...1.   208.726359: dma_buf_detach: dev_name=kgsl-3d0 exp_name=qcom,system name=ab pid [3317] size=217088 ino=2581 f_refcnt=3
>
> Signed-off-by: Xiang Gao <gaoxiang17@xiaomi.com>
> ---
>  drivers/dma-buf/dma-buf.c      |  57 ++++++++++-
>  include/trace/events/dma_buf.h | 166 +++++++++++++++++++++++++++++++++
>  2 files changed, 222 insertions(+), 1 deletion(-)
>  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 2bcf9ceca997..7cef816ddcac 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -35,6 +35,18 @@
>
>  #include "dma-buf-sysfs-stats.h"
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/dma_buf.h>
> +
> +EXPORT_TRACEPOINT_SYMBOL(dma_buf_export);
> +EXPORT_TRACEPOINT_SYMBOL(dma_buf_mmap_internal);
> +EXPORT_TRACEPOINT_SYMBOL(dma_buf_mmap);
> +EXPORT_TRACEPOINT_SYMBOL(dma_buf_put);
> +EXPORT_TRACEPOINT_SYMBOL(dma_buf_attach);
> +EXPORT_TRACEPOINT_SYMBOL(dma_buf_detach);
> +EXPORT_TRACEPOINT_SYMBOL(dma_buf_fd);
> +EXPORT_TRACEPOINT_SYMBOL(dma_buf_get);

Exporting the tracepoints is unecessary as far as I can see

> +
>  static inline int is_dma_buf_file(struct file *);
>
>  static DEFINE_MUTEX(dmabuf_list_mutex);
> @@ -220,6 +232,11 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
>           dmabuf->size >> PAGE_SHIFT)
>               return -EINVAL;
>
> +     if (trace_dma_buf_mmap_internal_enabled()) {
> +             guard(spinlock)(&dmabuf->name_lock);
> +             trace_dma_buf_mmap_internal(dmabuf);
> +     }
> +
>       return dmabuf->ops->mmap(dmabuf, vma);
>  }
>
> @@ -745,6 +762,11 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>
>       __dma_buf_list_add(dmabuf);
>
> +     if (trace_dma_buf_export_enabled()) {
> +             guard(spinlock)(&dmabuf->name_lock);
> +             trace_dma_buf_export(dmabuf);
> +     }
> +
>       return dmabuf;
>
>  err_dmabuf:
> @@ -779,6 +801,11 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags)
>
>       fd_install(fd, dmabuf->file);
>
> +     if (trace_dma_buf_fd_enabled()) {
> +             guard(spinlock)(&dmabuf->name_lock);
> +             trace_dma_buf_fd(dmabuf, fd);
> +     }
> +
>       return fd;
>  }
>  EXPORT_SYMBOL_NS_GPL(dma_buf_fd, "DMA_BUF");
> @@ -794,6 +821,7 @@ 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);
>
> @@ -805,7 +833,14 @@ struct dma_buf *dma_buf_get(int fd)
>               return ERR_PTR(-EINVAL);
>       }
>
> -     return file->private_data;
> +     dmabuf = file->private_data;
> +
> +     if (trace_dma_buf_get_enabled()) {
> +             guard(spinlock)(&dmabuf->name_lock);
> +             trace_dma_buf_get(dmabuf, fd);
> +     }
> +
> +     return dmabuf;
>  }
>  EXPORT_SYMBOL_NS_GPL(dma_buf_get, "DMA_BUF");
>
> @@ -825,6 +860,11 @@ void dma_buf_put(struct dma_buf *dmabuf)
>               return;
>
>       fput(dmabuf->file);
> +
> +     if (trace_dma_buf_put_enabled()) {
> +             guard(spinlock)(&dmabuf->name_lock);
> +             trace_dma_buf_put(dmabuf);
> +     }
>  }
>  EXPORT_SYMBOL_NS_GPL(dma_buf_put, "DMA_BUF");
>
> @@ -998,6 +1038,11 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, "DMA_BUF");
>  struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
>                                         struct device *dev)
>  {
> +     if (trace_dma_buf_attach_enabled()) {
> +             guard(spinlock)(&dmabuf->name_lock);
> +             trace_dma_buf_attach(dmabuf, dev);
> +     }
> +
>       return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);
>  }
>  EXPORT_SYMBOL_NS_GPL(dma_buf_attach, "DMA_BUF");
> @@ -1023,6 +1068,11 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
>       if (dmabuf->ops->detach)
>               dmabuf->ops->detach(dmabuf, attach);
>
> +     if (trace_dma_buf_detach_enabled()) {
> +             guard(spinlock)(&dmabuf->name_lock);
> +             trace_dma_buf_detach(dmabuf, attach->dev);
> +     }
> +
>       kfree(attach);
>  }
>  EXPORT_SYMBOL_NS_GPL(dma_buf_detach, "DMA_BUF");
> @@ -1488,6 +1538,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
>       vma_set_file(vma, dmabuf->file);
>       vma->vm_pgoff = pgoff;
>
> +     if (trace_dma_buf_mmap_enabled()) {
> +             guard(spinlock)(&dmabuf->name_lock);
> +             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..fe9da89bacd0
> --- /dev/null
> +++ b/include/trace/events/dma_buf.h
> @@ -0,0 +1,166 @@
> +/* 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)
> +             __string(name, dmabuf->name)
> +             __field(size_t, size)
> +             __field(ino_t, ino)
> +             __field(long, f_refcnt)
> +     ),
> +
> +     TP_fast_assign(
> +             __assign_str(exp_name);
> +             __assign_str(name);
> +             __entry->size = dmabuf->size;
> +             __entry->ino = dmabuf->file->f_inode->i_ino;
> +             __entry->f_refcnt = file_count(dmabuf->file);
> +     ),
> +
> +     TP_printk("exp_name=%s name=%s size=%zu ino=%lu f_refcnt=%ld",
> +               __get_str(exp_name),
> +               __get_str(name),
> +               __entry->size,
> +               __entry->ino,
> +               __entry->f_refcnt)

I can't come up with a reason why we should have the file refcount in the trace logs.

Same for most other places.

> +);
> +
> +DECLARE_EVENT_CLASS(dma_buf_attach_dev,
> +
> +     TP_PROTO(struct dma_buf *dmabuf, struct device *dev),
> +
> +     TP_ARGS(dmabuf, dev),
> +
> +     TP_STRUCT__entry(
> +             __string(dname, dev_name(dev))
> +             __string(exp_name, dmabuf->exp_name)
> +             __string(name, dmabuf->name)
> +             __field(size_t, size)
> +             __field(ino_t, ino)
> +             __field(long, f_refcnt)
> +     ),
> +
> +     TP_fast_assign(
> +             __assign_str(dname);
> +             __assign_str(exp_name);
> +             __assign_str(name);
> +             __entry->size = dmabuf->size;
> +             __entry->ino = dmabuf->file->f_inode->i_ino;
> +             __entry->f_refcnt = file_count(dmabuf->file);
> +     ),
> +
> +     TP_printk("dev_name=%s exp_name=%s name=%s size=%zu ino=%lu f_refcnt=%ld",
> +               __get_str(dname),
> +               __get_str(exp_name),
> +               __get_str(name),
> +               __entry->size,
> +               __entry->ino,
> +               __entry->f_refcnt)

Print the dev_name last, it's the external device which attaches to the DMA-buf.

Additional to that it would be nice to know if the attachment is dynamic or not.

Regards,
Christian.

> +);
> +
> +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)
> +             __string(name, dmabuf->name)
> +             __field(size_t, size)
> +             __field(ino_t, ino)
> +             __field(int, fd)
> +             __field(long, f_refcnt)
> +     ),
> +
> +     TP_fast_assign(
> +             __assign_str(exp_name);
> +             __assign_str(name);
> +             __entry->size = dmabuf->size;
> +             __entry->ino = dmabuf->file->f_inode->i_ino;
> +             __entry->fd = fd;
> +             __entry->f_refcnt = file_count(dmabuf->file);
> +     ),
> +
> +     TP_printk("exp_name=%s name=%s size=%zu ino=%lu fd=%d f_refcnt=%ld",
> +               __get_str(exp_name),
> +               __get_str(name),
> +               __entry->size,
> +               __entry->ino,
> +               __entry->fd,
> +               __entry->f_refcnt)
> +);
> +
> +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_attach,
> +
> +     TP_PROTO(struct dma_buf *dmabuf, struct device *dev),
> +
> +     TP_ARGS(dmabuf, dev)
> +);
> +
> +DEFINE_EVENT(dma_buf_attach_dev, dma_buf_detach,
> +
> +     TP_PROTO(struct dma_buf *dmabuf, struct device *dev),
> +
> +     TP_ARGS(dmabuf, 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>


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