tracing: Fix trace_seq_printf() return value

trace_seq_printf() return value is a little ambiguous. It
currently returns the length of the space available in the
buffer. printf usually returns the amount written. This is not
adequate here, because:

  trace_seq_printf(s, "");

is perfectly legal, and returning 0 would indicate that it
failed.

We can always see the amount written by looking at the before
and after values of s->len. This is not quite the same use as
printf. We only care if the string was successfully written to
the buffer or not.

Make trace_seq_printf() return 0 if the trace oversizes the
buffer's free space, 1 otherwise.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091023233646.631787612@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jiri Olsa 2009-10-23 19:36:17 -04:00 committed by Ingo Molnar
parent cf8517cf90
commit 3e69533b51

View file

@ -69,6 +69,9 @@ enum print_line_t trace_print_printk_msg_only(struct trace_iterator *iter)
* @s: trace sequence descriptor
* @fmt: printf format string
*
* It returns 0 if the trace oversizes the buffer's free
* space, 1 otherwise.
*
* The tracer may use either sequence operations or its own
* copy to user routines. To simplify formating of a trace
* trace_seq_printf is used to store strings into a special
@ -95,7 +98,7 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
s->len += ret;
return len;
return 1;
}
EXPORT_SYMBOL_GPL(trace_seq_printf);