In order to make libtraceevent into a proper library, its API should be straightforward. The trace_seq_printf() and trace_seq_vprintf() APIs have inconsistent returned values with the other trace_seq_* APIs. This path changes the return logic of trace_seq_printf() and trace_seq_vprintf() to return the number of printed characters, as the other trace_seq_* related APIs. Signed-off-by: Tzvetomir Stoyanov <tstoyanov@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Link: http://lkml.kernel.org/r/20181201040852.485792891@xxxxxxxxxxx Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> --- lib/traceevent/trace-seq.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/lib/traceevent/trace-seq.c b/lib/traceevent/trace-seq.c index 7f0c2f0..a20dab1 100644 --- a/lib/traceevent/trace-seq.c +++ b/lib/traceevent/trace-seq.c @@ -100,7 +100,8 @@ static void expand_buffer(struct trace_seq *s) * @fmt: printf format string * * It returns 0 if the trace oversizes the buffer's free - * space, 1 otherwise. + * space, the number of characters printed, or a negative + * value in case of an error. * * The tracer may use either sequence operations or its own * copy to user routines. To simplify formating of a trace @@ -129,9 +130,10 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...) goto try_again; } - s->len += ret; + if (ret > 0) + s->len += ret; - return 1; + return ret; } /** @@ -139,6 +141,10 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...) * @s: trace sequence descriptor * @fmt: printf format string * + * It returns 0 if the trace oversizes the buffer's free + * space, the number of characters printed, or a negative + * value in case of an error. + * * * 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 @@ -163,9 +169,10 @@ trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args) goto try_again; } - s->len += ret; + if (ret > 0) + s->len += ret; - return len; + return ret; } /** -- 2.20.1
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