On Mon, 30 Mar 2026 21:50:27 +0900
"Masami Hiramatsu (Google)" <[email protected]> wrote:
> @@ -2558,12 +2577,64 @@ static void rb_free_cpu_buffer(struct
> ring_buffer_per_cpu *cpu_buffer)
> kfree(cpu_buffer);
> }
>
> +#ifdef CONFIG_RING_BUFFER_PERSISTENT_INJECT
> +static void rb_test_inject_invalid_pages(struct trace_buffer *buffer)
> +{
> + struct ring_buffer_per_cpu *cpu_buffer;
> + struct ring_buffer_cpu_meta *meta;
> + struct buffer_data_page *dpage;
> + u32 entry_bytes = 0;
> + unsigned long ptr;
> + int subbuf_size;
> + int invalid = 0;
> + int cpu;
> + int i;
> +
> + if (!(buffer->flags & RB_FL_TESTING))
> + return;
> +
> + guard(preempt)();
> + cpu = smp_processor_id();
> +
> + cpu_buffer = buffer->buffers[cpu];
> + meta = cpu_buffer->ring_meta;
> + ptr = (unsigned long)rb_subbufs_from_meta(meta);
> + subbuf_size = meta->subbuf_size;
> +
> + for (i = 0; i < meta->nr_subbufs; i++) {
> + int idx = meta->buffers[i];
> +
> + dpage = (void *)(ptr + idx * subbuf_size);
> + /* Skip unused pages */
> + if (!local_read(&dpage->commit))
> + continue;
> +
> + /* Invalidate even pages. */
> + if (!(i & 0x1)) {
> + local_add(subbuf_size + 1, &dpage->commit);
> + invalid++;
> + } else {
> + /* Count total commit bytes. */
> + entry_bytes += local_read(&dpage->commit);
> + }
> + }
> +
> + pr_info("Inject invalidated %d pages on CPU%d, total size: %ld\n",
> + invalid, cpu, (long)entry_bytes);
This is only enabled when testing. Let's make that a pr_warn() as we really
do want to be able to see it. And it should warn that it is invalidating pages!
(warn as in pr_warn, it doesn't need a warn as in WARN()).
-- Steve
> + meta->nr_invalid = invalid;
> + meta->entry_bytes = entry_bytes;
> +}
> +#else /* !CONFIG_RING_BUFFER_PERSISTENT_INJECT */
> +#define rb_test_inject_invalid_pages(buffer) do { } while (0)
> +#endif
> +
> /* Stop recording on a persistent buffer and flush cache if needed. */
> static int rb_flush_buffer_cb(struct notifier_block *nb, unsigned long
> event, void *data)
> {
> struct trace_buffer *buffer = container_of(nb, struct trace_buffer,
> flush_nb);
>
> ring_buffer_record_off(buffer);
> + rb_test_inject_invalid_pages(buffer);
> arch_ring_buffer_flush_range(buffer->range_addr_start,
> buffer->range_addr_end);
> return NOTIFY_DONE;
> }
