On Sat, Feb 03, 2024 at 07:33:51PM -0500, Steven Rostedt wrote:
> On Mon, 29 Jan 2024 14:27:58 +0000
> Vincent Donnefort <vdonnef...@google.com> wrote:
>
> > --- /dev/null
> > +++ b/include/uapi/linux/trace_mmap.h
> > @@ -0,0 +1,43 @@
> > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> > +#ifndef _TRACE_MMAP_H_
> > +#define _TRACE_MMAP_H_
> > +
> > +#include <linux/types.h>
> > +
> > +/**
> > + * struct trace_buffer_meta - Ring-buffer Meta-page description
> > + * @meta_page_size: Size of this meta-page.
> > + * @meta_struct_len: Size of this structure.
> > + * @subbuf_size: Size of each subbuf, including the header.
>
> That is "the header"?
I mean the header of the "bpage". But that is confusing. I'll either remove that
mention or just say it is aligned with the order of a system page size.
>
> > + * @nr_subbufs: Number of subbfs in the ring-buffer.
> > + * @reader.lost_events: Number of events lost at the time of the reader
> > swap.
> > + * @reader.id: subbuf ID of the current reader. From 0 to
> > @nr_subbufs - 1
> > + * @reader.read: Number of bytes read on the reader subbuf.
>
> Note, flags needs a comment.
>
> > + * @entries: Number of entries in the ring-buffer.
> > + * @overrun: Number of entries lost in the ring-buffer.
> > + * @read: Number of entries that have been read.
>
> So does the two Reserved words, otherwise I'm going to start getting
> error reports about sparse warnings that check kerneldoc comments
> against their content. Every field needs to be represented in the
> kerneldoc comment.
Ack, wasn't sure it was needed.
>
> -- Steve
>
>
> > + */
> > +struct trace_buffer_meta {
> > + __u32 meta_page_size;
> > + __u32 meta_struct_len;
> > +
> > + __u32 subbuf_size;
> > + __u32 nr_subbufs;
> > +
> > + struct {
> > + __u64 lost_events;
> > + __u32 id;
> > + __u32 read;
> > + } reader;
> > +
> > + __u64 flags;
> > +
> > + __u64 entries;
> > + __u64 overrun;
> > + __u64 read;
> > +
> > + __u64 Reserved1;
> > + __u64 Reserved2;
> > +};
> > +
> > +#endif /* _TRACE_MMAP_H_ */
