Consumer-side ring buffer code uses architecture-specific smp_* helpers for shared memory accesses.
Use compiler atomics instead. They provide equivalent acquire and release ordering through a portable userspace interface and allow the next commit to use compiler fences in the wakeup protocol without mixing atomic interfaces. Assisted-by: Codex:gpt-5.5 Signed-off-by: Tamir Duberstein <[email protected]> --- tools/lib/bpf/ringbuf.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index b7adce37b519..1c24a83f59d5 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -264,13 +264,13 @@ static int64_t ringbuf_process_ring(struct ring *r, size_t n) if (n == 0) return 0; - cons_pos = smp_load_acquire(r->consumer_pos); + cons_pos = __atomic_load_n(r->consumer_pos, __ATOMIC_ACQUIRE); do { got_new_data = false; - prod_pos = smp_load_acquire(r->producer_pos); + prod_pos = __atomic_load_n(r->producer_pos, __ATOMIC_ACQUIRE); while (cons_pos != prod_pos) { len_ptr = r->data + (cons_pos & r->mask); - len = smp_load_acquire(len_ptr); + len = __atomic_load_n(len_ptr, __ATOMIC_ACQUIRE); /* sample not committed yet, bail out for now */ if (len & BPF_RINGBUF_BUSY_BIT) @@ -284,14 +284,16 @@ static int64_t ringbuf_process_ring(struct ring *r, size_t n) err = r->sample_cb(r->ctx, sample, len); if (err < 0) { /* update consumer pos and bail out */ - smp_store_release(r->consumer_pos, - cons_pos); + __atomic_store_n(r->consumer_pos, + cons_pos, + __ATOMIC_RELEASE); return err; } cnt++; } - smp_store_release(r->consumer_pos, cons_pos); + __atomic_store_n(r->consumer_pos, cons_pos, + __ATOMIC_RELEASE); if (cnt >= n) goto done; @@ -406,8 +408,8 @@ struct ring *ring_buffer__ring(struct ring_buffer *rb, unsigned int idx) unsigned long ring__consumer_pos(const struct ring *r) { - /* Synchronizes with smp_store_release() in ringbuf_process_ring(). */ - return smp_load_acquire(r->consumer_pos); + /* Synchronizes with the release store in ringbuf_process_ring(). */ + return __atomic_load_n(r->consumer_pos, __ATOMIC_ACQUIRE); } unsigned long ring__producer_pos(const struct ring *r) @@ -415,7 +417,7 @@ unsigned long ring__producer_pos(const struct ring *r) /* Synchronizes with smp_store_release() in __bpf_ringbuf_reserve() in * the kernel. */ - return smp_load_acquire(r->producer_pos); + return __atomic_load_n(r->producer_pos, __ATOMIC_ACQUIRE); } size_t ring__avail_data_size(const struct ring *r) -- 2.55.0.rc0.96.gc050c23164
