[PATCH v12] dma-buf: add some tracepoints to debug.
From: Xiang Gao <hidden>
Date: 2025-12-29 03:15:55
Also in:
linux-media, linux-trace-kernel, lkml
Subsystem:
dma buffer sharing framework, the rest, tracing · Maintainers:
Sumit Semwal, Christian König, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: gaoxiang17 <redacted>
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 <redacted>
---
Changes since v11: https://lore.kernel.org/all/20251225121119.2194228-1-gxxa03070307@gmail.com/ (local)
- Lined up the backslashes nicely for the macro DMA_BUF_TRACE.
- Used DEFINE_EVENT_CONDITION() to move the condition branch into the tracepoint.
Changes since v10: https://lore.kernel.org/all/20251224013455.1649879-1-gxxa03070307@gmail.com/ (local)
- Always expose dmabuf->name_lock if lockdep is enabled.
Changes since v9: https://lore.kernel.org/all/20251223032749.1371913-1-gxxa03070307@gmail.com/ (local)
- Fixed some whitespace issues with the macro DMA_BUF_TRACE again.
Changes since v8: https://lore.kernel.org/all/20251218062853.819744-1-gxxa03070307@gmail.com/ (local)
- Expose dmabuf->name_lock when lockdep is enabled but trace event is not.
Changes since v7: https://lore.kernel.org/all/20251217105132.643300-1-gxxa03070307@gmail.com/ (local)
- Fixed some whitespace issues with the macro DMA_BUF_TRACE.
Changes since v6: https://lore.kernel.org/all/20251216063952.516364-1-gxxa03070307@gmail.com/ (local)
- Add a comment for the macro DMA_BUF_TRACE.
Changes since v5: https://lore.kernel.org/all/20251201112148.843572-1-gxxa03070307@gmail.com/ (local)
- Add the macro DMA_BUF_TRACE.
- Modify the commit message.
Changes since v4: https://lore.kernel.org/all/20251128085215.550100-1-gxxa03070307@gmail.com/ (local)
- Remove the tracepoints exporting.
- Remove the file refcount for the trace.
- Print the dev_name last.
- Add the parameter of whether dma_buf attachment is dynamic.
Changes since v3: https://lore.kernel.org/all/20251127004352.376307-1-gxxa03070307@gmail.com/ (local)
- Take the dmabuf->name_lock around the tracepoint call itself.
- Used DECLARE_EVENT_CLASS() and a DEFINE_EVENT().
Changes since v2: https://lore.kernel.org/all/20251125162949.220488-1-gxxa03070307@gmail.com/ (local)
- Add more explanation to the commit message.
drivers/dma-buf/dma-buf.c | 48 +++++++++-
include/trace/events/dma_buf.h | 159 +++++++++++++++++++++++++++++++++
2 files changed, 205 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..dee59d4c0b12 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c@@ -35,6 +35,26 @@ #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 { \ + /* Always expose lock if lockdep is enabled */ \ + if (IS_ENABLED(CONFIG_LOCKDEP) || FUNC##_enabled()) { \ + guard(spinlock)(&dmabuf->name_lock); \ + FUNC(__VA_ARGS__); \ + } \ + } while (0) + static inline int is_dma_buf_file(struct file *); static DEFINE_MUTEX(dmabuf_list_mutex);
@@ -220,6 +240,8 @@ 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 +767,8 @@ 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 +792,15 @@ 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); + DMA_BUF_TRACE(trace_dma_buf_fd, dmabuf, fd); + + return fd; } EXPORT_SYMBOL_NS_GPL(dma_buf_fd, "DMA_BUF");
@@ -786,6 +815,7 @@ 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 +827,11 @@ 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 +851,8 @@ 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 +1007,9 @@ 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 +1054,9 @@ 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 +1522,8 @@ 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..3bb88d05bcc8
--- /dev/null
+++ b/include/trace/events/dma_buf.h@@ -0,0 +1,159 @@ +/* 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_CONDITION(dma_buf_fd, dma_buf_fd, + + TP_PROTO(struct dma_buf *dmabuf, int fd), + + TP_ARGS(dmabuf, fd), + + TP_CONDITION(fd >= 0) +); + +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>
--
2.34.1