[PATCH 2/4] bpf: Add dmabuf iterator

[T.J. Mercier]

On Tue, Apr 15, 2025 at 9:43 PM kernel test robot <lkp at intel.com> wrote:
>
> Hi Mercier,
>
> kernel test robot noticed the following build errors:
>
> [auto build test ERROR on bpf-next/net]
> [also build test ERROR on bpf-next/master bpf/master linus/master v6.15-rc2 next-20250415]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/T-J-Mercier/dma-buf-Rename-and-expose-debugfs-symbols/20250415-065354
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git net
> patch link:    https://lore.kernel.org/r/20250414225227.3642618-3-tjmercier%40google.com
> patch subject: [PATCH 2/4] bpf: Add dmabuf iterator
> config: i386-buildonly-randconfig-005-20250416
> compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
> reproduce (this is a W=1 build):
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp at intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202504161015.x2XLaha2-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
> >> ld.lld: error: undefined symbol: dmabuf_debugfs_list_mutex
>    >>> referenced by dmabuf_iter.c:44 (kernel/bpf/dmabuf_iter.c:44)
>    >>>               vmlinux.o:(dmabuf_iter_seq_next)
>    >>> referenced by dmabuf_iter.c:53 (kernel/bpf/dmabuf_iter.c:53)
>    >>>               vmlinux.o:(dmabuf_iter_seq_next)
>    >>> referenced by dmabuf_iter.c:26 (kernel/bpf/dmabuf_iter.c:26)
>    >>>               vmlinux.o:(dmabuf_iter_seq_start)
>    >>> referenced 1 more times
> --
> >> ld.lld: error: undefined symbol: dma_buf_put
>    >>> referenced by dmabuf_iter.c:45 (kernel/bpf/dmabuf_iter.c:45)
>    >>>               vmlinux.o:(dmabuf_iter_seq_next)
>    >>> referenced by dmabuf_iter.c:90 (kernel/bpf/dmabuf_iter.c:90)
>    >>>               vmlinux.o:(dmabuf_iter_seq_stop)
> --
> >> ld.lld: error: undefined symbol: dmabuf_debugfs_list
>    >>> referenced by list.h:354 (include/linux/list.h:354)
>    >>>               vmlinux.o:(dmabuf_iter_seq_next)
>    >>> referenced by dmabuf_iter.c:0 (kernel/bpf/dmabuf_iter.c:0)
>    >>>               vmlinux.o:(dmabuf_iter_seq_start)
>    >>> referenced by list.h:364 (include/linux/list.h:364)
>    >>>               vmlinux.o:(dmabuf_iter_seq_start)
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki

This is due to no CONFIG_DMA_SHARED_BUFFER. Fixed by:

--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -53,7 +53,7 @@ obj-$(CONFIG_BPF_SYSCALL) += relo_core.o
 obj-$(CONFIG_BPF_SYSCALL) += btf_iter.o
 obj-$(CONFIG_BPF_SYSCALL) += btf_relocate.o
 obj-$(CONFIG_BPF_SYSCALL) += kmem_cache_iter.o
-ifeq ($(CONFIG_DEBUG_FS),y)
+ifeq ($(CONFIG_DMA_SHARED_BUFFER)$(CONFIG_DEBUG_FS),yy)
 obj-$(CONFIG_BPF_SYSCALL) += dmabuf_iter.o
 endif