Re: [PATCH -tip 2/3] Tracing/ftrace: Adapt mmiotrace to the newtype of print_line

From: Pekka Paalanen
Date: Fri Sep 26 2008 - 17:22:08 EST


On Fri, 26 Sep 2008 17:44:07 +0200
Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote:

> Adapt mmiotrace to the new print_line type.
> By default, it refuses types it doesn't support.
> But a tracer needs to print something to the seq anyway.
> That's why it needs to warn about unsupported types.
>
> Pekka if you disagree with it, please don't hesitate to tell me.

Yes, I do disagree about printing stuff that doesn't belong there.
First, I doubt printing bogus text is a right way to fix the
early pipe EOF problem. Second, if you really have to do that,
do it so that it obeys the mmiotrace log format specification.
(I'd recommend a MARK entry.) The spec is in
Documentation/tracers/mmiotrace.txt.

This is just a very quick comment, and I should look at your two
patches better. I hope to do that during the weekend.

Was there supposed to be a third patch, as the subject suggests?

Thanks.


> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> ---
> diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
> index 2bbb7dd..69480a5 100644
> --- a/kernel/trace/trace_mmiotrace.c
> +++ b/kernel/trace/trace_mmiotrace.c
> @@ -171,7 +171,7 @@ print_out:
> return (ret == -EBUSY) ? 0 : ret;
> }
>
> -static int mmio_print_rw(struct trace_iterator *iter)
> +static enum print_line_t mmio_print_rw(struct trace_iterator *iter)
> {
> struct trace_entry *entry = iter->ent;
> struct mmiotrace_rw *rw = &entry->field.mmiorw;
> @@ -209,11 +209,11 @@ static int mmio_print_rw(struct trace_iterator *iter)
> break;
> }
> if (ret)
> - return 1;
> - return 0;
> + return TRACE_TYPE_HANDLED;
> + return TRACE_TYPE_PARTIAL_LINE;
> }
>
> -static int mmio_print_map(struct trace_iterator *iter)
> +static enum print_line_t mmio_print_map(struct trace_iterator *iter)
> {
> struct trace_entry *entry = iter->ent;
> struct mmiotrace_map *m = &entry->field.mmiomap;
> @@ -221,7 +221,7 @@ static int mmio_print_map(struct trace_iterator *iter)
> unsigned long long t = ns2usecs(entry->field.t);
> unsigned long usec_rem = do_div(t, 1000000ULL);
> unsigned secs = (unsigned long)t;
> - int ret = 1;
> + int ret;
>
> switch (entry->field.mmiorw.opcode) {
> case MMIO_PROBE:
> @@ -241,11 +241,11 @@ static int mmio_print_map(struct trace_iterator *iter)
> break;
> }
> if (ret)
> - return 1;
> - return 0;
> + return TRACE_TYPE_HANDLED;
> + return TRACE_TYPE_PARTIAL_LINE;
> }
>
> -static int mmio_print_mark(struct trace_iterator *iter)
> +static enum print_line_t mmio_print_mark(struct trace_iterator *iter)
> {
> struct trace_entry *entry = iter->ent;
> const char *msg = entry->field.print.buf;
> @@ -258,16 +258,16 @@ static int mmio_print_mark(struct trace_iterator *iter)
> /* The trailing newline must be in the message. */
> ret = trace_seq_printf(s, "MARK %lu.%06lu %s", secs, usec_rem, msg);
> if (!ret)
> - return 0;
> + return TRACE_TYPE_PARTIAL_LINE;
>
> if (entry->field.flags & TRACE_FLAG_CONT)
> trace_seq_print_cont(s, iter);
>
> - return 1;
> + return TRACE_TYPE_HANDLED;
> }
>
> /* return 0 to abort printing without consuming current entry in pipe mode */
> -static int mmio_print_line(struct trace_iterator *iter)
> +static enum print_line_t mmio_print_line(struct trace_iterator *iter)
> {
> switch (iter->ent->type) {
> case TRACE_MMIO_RW:
> @@ -277,7 +277,9 @@ static int mmio_print_line(struct trace_iterator *iter)
> case TRACE_PRINT:
> return mmio_print_mark(iter);
> default:
> - return 0; /* ignore unknown entries whithout consuming */
> + /* ignore unknown entries */
> + trace_seq_printf(&iter->seq, "Unknown trace type\n");
> + return TRACE_TYPE_HANDLED;
> }
> }
>
>


--
Pekka Paalanen
http://www.iki.fi/pq/
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