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Subject[tip:perf/urgent] tools lib traceevent: Changed return logic of trace_seq_printf() and trace_seq_vprintf() APIs
Commit-ID:  6d2d6fd7e3ee0daf0d8308741792b3ec41aafd0c
Gitweb: https://git.kernel.org/tip/6d2d6fd7e3ee0daf0d8308741792b3ec41aafd0c
Author: Tzvetomir Stoyanov <tstoyanov@vmware.com>
AuthorDate: Fri, 30 Nov 2018 23:08:10 -0500
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 8 Jan 2019 13:28:13 -0300

tools lib traceevent: Changed return logic of trace_seq_printf() and trace_seq_vprintf() APIs

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@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20181201040852.485792891@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/lib/traceevent/trace-seq.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/tools/lib/traceevent/trace-seq.c b/tools/lib/traceevent/trace-seq.c
index 8ff1d55954d1..8d5ecd2bf877 100644
--- a/tools/lib/traceevent/trace-seq.c
+++ b/tools/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;
}

/**
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