linux-kernel - Re: [PATCH v4] dma-buf: add some tracepoints to debug.

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Message-ID: <CAGsJ_4y0zc_nh2q=w4uR04vtveCf6L7+hgafznHuL8ByWbyNOQ@mail.gmail.com>
Date: Fri, 28 Nov 2025 17:31:46 +0800
From: Barry Song <21cnbao@...il.com>
To: Xiang Gao <gxxa03070307@...il.com>
Cc: sumit.semwal@...aro.org, christian.koenig@....com, rostedt@...dmis.org, 
	mhiramat@...nel.org, linux-media@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	mathieu.desnoyers@...icios.com, dhowells@...hat.com, kuba@...nel.org, 
	brauner@...nel.org, akpm@...ux-foundation.org, 
	linux-trace-kernel@...r.kernel.org, gaoxiang17 <gaoxiang17@...omi.com>
Subject: Re: [PATCH v4] dma-buf: add some tracepoints to debug.

On Fri, Nov 28, 2025 at 4:53 PM Xiang Gao <gxxa03070307@...il.com> wrote:
>
> From: gaoxiang17 <gaoxiang17@...omi.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.

might be:

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:3031_4-18348   [005] ...1.   545.568275: dma_buf_export: exp_name=qcom,system name=(null) size=217088 ino=2750
>    binder:3031_4-18348   [005] ...1.   545.568284: dma_buf_fd: exp_name=qcom,system name=(null) size=217088 ino=2750 fd=8
>    binder:3031_4-18348   [005] ...1.   545.568399: dma_buf_mmap_internal: exp_name=qcom,system name=qcom,system size=28672 ino=2751
>      kworker/5:1-130     [005] ...1.   545.570193: dma_buf_put: exp_name=qcom,system name=ab size=28672 ino=2751
>     RenderThread-18891   [005] ...1.   545.602994: dma_buf_get: exp_name=qcom,system name=ab size=217088 ino=2750 fd=1087
>     RenderThread-9409    [000] .n.1.   545.745004: dma_buf_dynamic_attach: exp_name=qcom,system name=ab size=217088 ino=2750 is_dynamic=0 dev_name=kgsl-3d0
>     RenderThread-9409    [005] ...1.   545.747802: dma_buf_detach: exp_name=qcom,system name=bq size=12771328 ino=2764 is_dynamic=0 dev_name=kgsl-3d0
>
> Signed-off-by: Xiang Gao <gaoxiang17@...omi.com>
> ---
>  drivers/dma-buf/dma-buf.c      |  48 +++++++++-
>  include/trace/events/dma_buf.h | 160 +++++++++++++++++++++++++++++++++
>  2 files changed, 207 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..6e04e12f149e 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -35,6 +35,9 @@
>
>  #include "dma-buf-sysfs-stats.h"
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/dma_buf.h>
> +
>  static inline int is_dma_buf_file(struct file *);
>
>  static DEFINE_MUTEX(dmabuf_list_mutex);
> @@ -220,6 +223,11 @@ 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 +753,11 @@ 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);
> +       }
> +

perhaps a macro similar to the one below

#define DMA_BUF_TRACE(FUNC, ...)                  \
    do {                                          \
        if (FUNC##_enabled()) {                   \
            guard(spinlock)(&dmabuf->name_lock); \
            FUNC(__VA_ARGS__);                    \
        }                                         \
    } while (0)


This would help us avoid duplicating a lot of code.

could be:
DMA_BUF_TRACE(trace_dma_buf_put, dmabuf);
DMA_BUF_TRACE(trace_dma_buf_attach, dmabuf, dev);

?