On Tue, 23 Jan 2024 09:52:55 +0000
Vincent Donnefort <vdonnefort@xxxxxxxxxx> wrote:
> [...]
>
> > + data = tmap->data + tmap->map->subbuf_size * tmap->last_idx;
> > + kbuffer_load_subbuffer(kbuf, data);
Only the tmap->kbuf is loaded above.
> > +
> > + /*
> > + * The page could have left over data on it that was already
> > + * consumed. Move the "read" forward in that case.
> > + */
> > + if (tmap->map->reader.read) {
> > + int size = kbuffer_start_of_data(kbuf) + tmap->map->reader.read;
> > + char tmpbuf[size];
> > + kbuffer_read_buffer(kbuf, tmpbuf, size);
> > + }
>
> We're fast-forwarding tmap->kbuf here. But in tracefs_cpu_read_buf(), we are
> using tcpu->kbuf. So overall, it seems this has no effect on what will be read
> later.
>
> Sorry, not sure how I missed that when I worked with those changes before.
So we would need to add this in trace_mmap_load_subbuf()?
if (data != kbuffer_subbuffer(kbuf)) {
kbuffer_load_subbuffer(kbuf, data);
+ /* Move the read pointer forward if need be */
+ if (kbuffer_curr_index(tmap->kbuf)) {
+ int size = kbuffer_curr_index(tmap->kbuf);
+ char tmpbuf[size];
+ kbuffer_read_buffer(kbuf, tmpbuf, size);
+ }
return 1;
}
I think that could solve that.
-- Steve
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