Commit 4448f64c authored by Martin Kelly's avatar Martin Kelly Committed by Andrii Nakryiko
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libbpf: Refactor cleanup in ring_buffer__add 



Refactor the cleanup code in ring_buffer__add to use a unified err_out
label. This reduces code duplication, as well as plugging a potential
leak if mmap_sz != (__u64)(size_t)mmap_sz (currently this would miss
unmapping tmp because ringbuf_unmap_ring isn't called).

Signed-off-by: default avatarMartin Kelly <martin.kelly@crowdstrike.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230925215045.2375758-2-martin.kelly@crowdstrike.com
parent 831916fb

tools/lib/bpf/ringbuf.c

+9 −6
Original line number Diff line number Diff line
@@ -121,7 +121,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, 
		err = -errno;

		pr_warn("ringbuf: failed to mmap consumer page for map fd=%d: %d\n",

			map_fd, err);

		return libbpf_err(err);

		goto err_out;

	}

	r->consumer_pos = tmp;
@@ -131,16 +131,16 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, 
	 */

	mmap_sz = rb->page_size + 2 * (__u64)info.max_entries;

	if (mmap_sz != (__u64)(size_t)mmap_sz) {

		err = -E2BIG;

		pr_warn("ringbuf: ring buffer size (%u) is too big\n", info.max_entries);

		return libbpf_err(-E2BIG);

		goto err_out;

	}

	tmp = mmap(NULL, (size_t)mmap_sz, PROT_READ, MAP_SHARED, map_fd, rb->page_size);

	if (tmp == MAP_FAILED) {

		err = -errno;

		ringbuf_unmap_ring(rb, r);

		pr_warn("ringbuf: failed to mmap data pages for map fd=%d: %d\n",

			map_fd, err);

		return libbpf_err(err);

		goto err_out;

	}

	r->producer_pos = tmp;

	r->data = tmp + rb->page_size;
@@ -152,14 +152,17 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, 
	e->data.fd = rb->ring_cnt;

	if (epoll_ctl(rb->epoll_fd, EPOLL_CTL_ADD, map_fd, e) < 0) {

		err = -errno;

		ringbuf_unmap_ring(rb, r);

		pr_warn("ringbuf: failed to epoll add map fd=%d: %d\n",

			map_fd, err);

		return libbpf_err(err);

		goto err_out;

	}



	rb->ring_cnt++;

	return 0;



err_out:

	ringbuf_unmap_ring(rb, r);

	return libbpf_err(err);

}



void ring_buffer__free(struct ring_buffer *rb)