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From: Tzvetomir Stoyanov <tstoyanov@vmware.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: [PATCH 3/6] trace-cmd: Changed return logic of trace_seq_printf() and trace_seq_vprintf() APIs
Date: Wed, 30 Jan 2019 12:44:22 +0200
Message-ID: <20190130104425.8813-4-tstoyanov@vmware.com> (raw)
In-Reply-To: <20190130104425.8813-1-tstoyanov@vmware.com>

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>
---
 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


  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-30 10:44 [PATCH 0/6] Few patches, backported from Arnaldo's kernel repo Tzvetomir Stoyanov
2019-01-30 10:44 ` [PATCH 1/6] trace-cmd: Initialize host_bigendian at tep_handle allocation Tzvetomir Stoyanov
2019-01-30 10:44 ` [PATCH 2/6] trace_cmd: Rename struct cmdline to struct tep_cmdline Tzvetomir Stoyanov
2019-01-30 10:44 ` Tzvetomir Stoyanov [this message]
2019-01-30 10:44 ` [PATCH 4/6] trace-cmd: Changed return logic of tep_register_event_handler() API Tzvetomir Stoyanov
2019-01-30 10:44 ` [PATCH 5/6] trace-cmd: Rename tep_is_file_bigendian() to tep_file_bigendian() Tzvetomir Stoyanov
2019-01-30 10:44 ` [PATCH 6/6] trace-cmd: Remove tep_data_event_from_type() API Tzvetomir Stoyanov

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