diff options
| author | Martin Kelly <martin.kelly@crowdstrike.com> | 2023-09-25 14:50:33 -0700 |
|---|---|---|
| committer | Andrii Nakryiko <andrii.nakryiko@gmail.com> | 2023-10-02 11:17:48 -0700 |
| commit | bfa471bc859b9aebfbf72d953314165a0dc1c172 (patch) | |
| tree | fbe6b2392b5bc33399a8db287324c8b52b5f3c9c | |
| parent | 64f2b4ab4914398c958a7a040743590ddf4b7b7c (diff) | |
| download | libbpf-bfa471bc859b9aebfbf72d953314165a0dc1c172.tar.gz | |
libbpf: Switch rings to array of pointers
Switch rb->rings to be an array of pointers instead of a contiguous
block. This allows for each ring pointer to be stable after
ring_buffer__add is called, which allows us to expose struct ring * to
the user without gotchas. Without this change, the realloc in
ring_buffer__add could invalidate a struct ring *, making it unsafe to
give to the user.
Signed-off-by: Martin Kelly <martin.kelly@crowdstrike.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230925215045.2375758-3-martin.kelly@crowdstrike.com
| -rw-r--r-- | src/ringbuf.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/src/ringbuf.c b/src/ringbuf.c index 29b0d19..94d11fb 100644 --- a/src/ringbuf.c +++ b/src/ringbuf.c @@ -34,7 +34,7 @@ struct ring { struct ring_buffer { struct epoll_event *events; - struct ring *rings; + struct ring **rings; size_t page_size; int epoll_fd; int ring_cnt; @@ -57,7 +57,7 @@ struct ringbuf_hdr { __u32 pad; }; -static void ringbuf_unmap_ring(struct ring_buffer *rb, struct ring *r) +static void ringbuf_free_ring(struct ring_buffer *rb, struct ring *r) { if (r->consumer_pos) { munmap(r->consumer_pos, rb->page_size); @@ -67,6 +67,8 @@ static void ringbuf_unmap_ring(struct ring_buffer *rb, struct ring *r) munmap(r->producer_pos, rb->page_size + 2 * (r->mask + 1)); r->producer_pos = NULL; } + + free(r); } /* Add extra RINGBUF maps to this ring buffer manager */ @@ -107,8 +109,10 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, return libbpf_err(-ENOMEM); rb->events = tmp; - r = &rb->rings[rb->ring_cnt]; - memset(r, 0, sizeof(*r)); + r = calloc(1, sizeof(*r)); + if (!r) + return libbpf_err(-ENOMEM); + rb->rings[rb->ring_cnt] = r; r->map_fd = map_fd; r->sample_cb = sample_cb; @@ -161,7 +165,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd, return 0; err_out: - ringbuf_unmap_ring(rb, r); + ringbuf_free_ring(rb, r); return libbpf_err(err); } @@ -173,7 +177,7 @@ void ring_buffer__free(struct ring_buffer *rb) return; for (i = 0; i < rb->ring_cnt; ++i) - ringbuf_unmap_ring(rb, &rb->rings[i]); + ringbuf_free_ring(rb, rb->rings[i]); if (rb->epoll_fd >= 0) close(rb->epoll_fd); @@ -281,7 +285,7 @@ int ring_buffer__consume(struct ring_buffer *rb) int i; for (i = 0; i < rb->ring_cnt; i++) { - struct ring *ring = &rb->rings[i]; + struct ring *ring = rb->rings[i]; err = ringbuf_process_ring(ring); if (err < 0) @@ -308,7 +312,7 @@ int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms) for (i = 0; i < cnt; i++) { __u32 ring_id = rb->events[i].data.fd; - struct ring *ring = &rb->rings[ring_id]; + struct ring *ring = rb->rings[ring_id]; err = ringbuf_process_ring(ring); if (err < 0) |