Commit 3e69533b authored Oct 23, 2009 by Jiri Olsa Committed by Ingo Molnar Oct 24, 2009

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>

parent cf8517cf

kernel/trace/trace_output.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -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);