bpf: Add dmabuf iterator (76ea9553) · Commits · git / linux-net

drivers/dma-buf/dma-buf.c

+68 −0

Original line number	Diff line number	Diff line
		@@ -19,7 +19,9 @@
		#include <linux/anon_inodes.h>
		#include <linux/export.h>
		#include <linux/debugfs.h>
		#include <linux/list.h>
		#include <linux/module.h>
		#include <linux/mutex.h>
		#include <linux/seq_file.h>
		#include <linux/sync_file.h>
		#include <linux/poll.h>
		@@ -55,6 +57,72 @@ static void __dma_buf_list_del(struct dma_buf *dmabuf)
		mutex_unlock(&dmabuf_list_mutex);
		}

		/**
		* dma_buf_iter_begin - begin iteration through global list of all DMA buffers
		*
		* Returns the first buffer in the global list of DMA-bufs that's not in the
		* process of being destroyed. Increments that buffer's reference count to
		* prevent buffer destruction. Callers must release the reference, either by
		* continuing iteration with dma_buf_iter_next(), or with dma_buf_put().
		*
		* Return:
		* * First buffer from global list, with refcount elevated
		* * NULL if no active buffers are present
		*/
		struct dma_buf *dma_buf_iter_begin(void)
		{
		struct dma_buf ret = NULL, dmabuf;

		/*
		* The list mutex does not protect a dmabuf's refcount, so it can be
		* zeroed while we are iterating. We cannot call get_dma_buf() since the
		* caller may not already own a reference to the buffer.
		*/
		mutex_lock(&dmabuf_list_mutex);
		list_for_each_entry(dmabuf, &dmabuf_list, list_node) {
		if (file_ref_get(&dmabuf->file->f_ref)) {
		ret = dmabuf;
		break;
		}
		}
		mutex_unlock(&dmabuf_list_mutex);
		return ret;
		}

		/**
		* dma_buf_iter_next - continue iteration through global list of all DMA buffers
		* @dmabuf: [in] pointer to dma_buf
		*
		* Decrements the reference count on the provided buffer. Returns the next
		* buffer from the remainder of the global list of DMA-bufs with its reference
		* count incremented. Callers must release the reference, either by continuing
		* iteration with dma_buf_iter_next(), or with dma_buf_put().
		*
		* Return:
		* * Next buffer from global list, with refcount elevated
		* * NULL if no additional active buffers are present
		*/
		struct dma_buf dma_buf_iter_next(struct dma_buf dmabuf)
		{
		struct dma_buf *ret = NULL;

		/*
		* The list mutex does not protect a dmabuf's refcount, so it can be
		* zeroed while we are iterating. We cannot call get_dma_buf() since the
		* caller may not already own a reference to the buffer.
		*/
		mutex_lock(&dmabuf_list_mutex);
		dma_buf_put(dmabuf);
		list_for_each_entry_continue(dmabuf, &dmabuf_list, list_node) {
		if (file_ref_get(&dmabuf->file->f_ref)) {
		ret = dmabuf;
		break;
		}
		}
		mutex_unlock(&dmabuf_list_mutex);
		return ret;
		}

		static char dmabuffs_dname(struct dentry dentry, char *buffer, int buflen)
		{
		struct dma_buf *dmabuf;

include/linux/dma-buf.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -634,4 +634,6 @@ int dma_buf_vmap(struct dma_buf dmabuf, struct iosys_map map);
		void dma_buf_vunmap(struct dma_buf dmabuf, struct iosys_map map);
		int dma_buf_vmap_unlocked(struct dma_buf dmabuf, struct iosys_map map);
		void dma_buf_vunmap_unlocked(struct dma_buf dmabuf, struct iosys_map map);
		struct dma_buf *dma_buf_iter_begin(void);
		struct dma_buf dma_buf_iter_next(struct dma_buf dmbuf);
		#endif /* __DMA_BUF_H__ */

kernel/bpf/Makefile

+3 −0

Original line number	Diff line number	Diff line
		@@ -53,6 +53,9 @@ 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 ($(CONFIG_DMA_SHARED_BUFFER),y)
		obj-$(CONFIG_BPF_SYSCALL) += dmabuf_iter.o
		endif

		CFLAGS_REMOVE_percpu_freelist.o = $(CC_FLAGS_FTRACE)
		CFLAGS_REMOVE_bpf_lru_list.o = $(CC_FLAGS_FTRACE)

kernel/bpf/dmabuf_iter.c

0 → 100644

+102 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0-only
		/* Copyright (c) 2025 Google LLC */
		#include <linux/bpf.h>
		#include <linux/btf_ids.h>
		#include <linux/dma-buf.h>
		#include <linux/kernel.h>
		#include <linux/seq_file.h>

		static void dmabuf_iter_seq_start(struct seq_file seq, loff_t *pos)
		{
		if (*pos)
		return NULL;

		return dma_buf_iter_begin();
		}

		static void dmabuf_iter_seq_next(struct seq_file seq, void v, loff_t pos)
		{
		struct dma_buf *dmabuf = v;

		++*pos;

		return dma_buf_iter_next(dmabuf);
		}

		struct bpf_iter__dmabuf {
		__bpf_md_ptr(struct bpf_iter_meta *, meta);
		__bpf_md_ptr(struct dma_buf *, dmabuf);
		};

		static int __dmabuf_seq_show(struct seq_file seq, void v, bool in_stop)
		{
		struct bpf_iter_meta meta = {
		.seq = seq,
		};
		struct bpf_iter__dmabuf ctx = {
		.meta = &meta,
		.dmabuf = v,
		};
		struct bpf_prog *prog = bpf_iter_get_info(&meta, in_stop);

		if (prog)
		return bpf_iter_run_prog(prog, &ctx);

		return 0;
		}

		static int dmabuf_iter_seq_show(struct seq_file seq, void v)
		{
		return __dmabuf_seq_show(seq, v, false);
		}

		static void dmabuf_iter_seq_stop(struct seq_file seq, void v)
		{
		struct dma_buf *dmabuf = v;

		if (dmabuf)
		dma_buf_put(dmabuf);
		}

		static const struct seq_operations dmabuf_iter_seq_ops = {
		.start = dmabuf_iter_seq_start,
		.next = dmabuf_iter_seq_next,
		.stop = dmabuf_iter_seq_stop,
		.show = dmabuf_iter_seq_show,
		};

		static void bpf_iter_dmabuf_show_fdinfo(const struct bpf_iter_aux_info *aux,
		struct seq_file *seq)
		{
		seq_puts(seq, "dmabuf iter\n");
		}

		static const struct bpf_iter_seq_info dmabuf_iter_seq_info = {
		.seq_ops = &dmabuf_iter_seq_ops,
		.init_seq_private = NULL,
		.fini_seq_private = NULL,
		.seq_priv_size = 0,
		};

		static struct bpf_iter_reg bpf_dmabuf_reg_info = {
		.target = "dmabuf",
		.feature = BPF_ITER_RESCHED,
		.show_fdinfo = bpf_iter_dmabuf_show_fdinfo,
		.ctx_arg_info_size = 1,
		.ctx_arg_info = {
		{ offsetof(struct bpf_iter__dmabuf, dmabuf),
		PTR_TO_BTF_ID_OR_NULL },
		},
		.seq_info = &dmabuf_iter_seq_info,
		};

		DEFINE_BPF_ITER_FUNC(dmabuf, struct bpf_iter_meta meta, struct dma_buf dmabuf)
		BTF_ID_LIST_SINGLE(bpf_dmabuf_btf_id, struct, dma_buf)

		static int __init dmabuf_iter_init(void)
		{
		bpf_dmabuf_reg_info.ctx_arg_info[0].btf_id = bpf_dmabuf_btf_id[0];
		return bpf_iter_reg_target(&bpf_dmabuf_reg_info);
		}

		late_initcall(dmabuf_iter_init);