diff options
| author | Andrea Righi <andrea.righi@canonical.com> | 2024-04-06 11:15:42 +0200 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-04-06 09:11:54 -0700 |
| commit | 13e8125a22763557d719db996f70c71f77c9509c (patch) | |
| tree | 55cc123f3de1470b1741461a5812b14dba737031 /tools/lib/bpf | |
| parent | 5bd2ed658231b0698211e94efb06393836a4539d (diff) | |
libbpf: ringbuf: Allow to consume up to a certain amount of items
In some cases, instead of always consuming all items from ring buffers
in a greedy way, we may want to consume up to a certain amount of items,
for example when we need to copy items from the BPF ring buffer to a
limited user buffer.
This change allows to set an upper limit to the amount of items consumed
from one or more ring buffers.
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240406092005.92399-3-andrea.righi@canonical.com
Diffstat (limited to 'tools/lib/bpf')
| -rw-r--r-- | tools/lib/bpf/ringbuf.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index aacb64278a01..db05e6f526de 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -231,7 +231,7 @@ static inline int roundup_len(__u32 len) return (len + 7) / 8 * 8; } -static int64_t ringbuf_process_ring(struct ring *r) +static int64_t ringbuf_process_ring(struct ring *r, size_t n) { int *len_ptr, len, err; /* 64-bit to avoid overflow in case of extreme application behavior */ @@ -268,6 +268,9 @@ static int64_t ringbuf_process_ring(struct ring *r) } smp_store_release(r->consumer_pos, cons_pos); + + if (cnt >= n) + goto done; } } while (got_new_data); done: @@ -287,13 +290,15 @@ int ring_buffer__consume(struct ring_buffer *rb) for (i = 0; i < rb->ring_cnt; i++) { struct ring *ring = rb->rings[i]; - err = ringbuf_process_ring(ring); + err = ringbuf_process_ring(ring, INT_MAX); if (err < 0) return libbpf_err(err); res += err; + if (res > INT_MAX) { + res = INT_MAX; + break; + } } - if (res > INT_MAX) - return INT_MAX; return res; } @@ -314,13 +319,13 @@ int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms) __u32 ring_id = rb->events[i].data.fd; struct ring *ring = rb->rings[ring_id]; - err = ringbuf_process_ring(ring); + err = ringbuf_process_ring(ring, INT_MAX); if (err < 0) return libbpf_err(err); res += err; } if (res > INT_MAX) - return INT_MAX; + res = INT_MAX; return res; } @@ -375,7 +380,7 @@ int ring__consume(struct ring *r) { int64_t res; - res = ringbuf_process_ring(r); + res = ringbuf_process_ring(r, INT_MAX); if (res < 0) return libbpf_err(res); |