[tip:perf/urgent] perf mmap: Add new return value logic for perf_mmap__read_init()

[tip-bot for Kan Liang <tipbot@zytor.com>]

Commit-ID:  189f2cc91f9f2efef5d5f4dde43684c01b5f6f2f
Gitweb:     https://git.kernel.org/tip/189f2cc91f9f2efef5d5f4dde43684c01b5f6f2f
Author:     Kan Liang <kan.liang@intel.com>
AuthorDate: Thu, 18 Jan 2018 13:26:20 -0800
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 15 Feb 2018 09:52:49 -0300

perf mmap: Add new return value logic for perf_mmap__read_init()

Improve the readability by using meaningful enum (-EAGAIN, -EINVAL and
0) to replace the three returning states (0, -1 and 1).

Suggested-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-6-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/mmap.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index c19a4e6..38fa69d 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -282,7 +282,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
 	*endp = overwrite ? old : head;
 
 	if (*startp == *endp)
-		return 0;
+		return -EAGAIN;
 
 	size = *endp - *startp;
 	if (size > (unsigned long)(md->mask) + 1) {
@@ -291,7 +291,7 @@ int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
 
 			md->prev = head;
 			perf_mmap__consume(md, overwrite);
-			return 0;
+			return -EAGAIN;
 		}
 
 		/*
@@ -299,10 +299,10 @@ int perf_mmap__read_init(struct perf_mmap *md, bool overwrite,
 		 * most of data from it.
 		 */
 		if (overwrite_rb_find_range(data, md->mask, head, startp, endp))
-			return -1;
+			return -EINVAL;
 	}
 
-	return 1;
+	return 0;
 }
 
 int perf_mmap__push(struct perf_mmap *md, bool overwrite,
@@ -316,8 +316,8 @@ int perf_mmap__push(struct perf_mmap *md, bool overwrite,
 	int rc = 0;
 
 	rc = perf_mmap__read_init(md, overwrite, &start, &end);
-	if (rc < 1)
-		return rc;
+	if (rc < 0)
+		return (rc == -EAGAIN) ? 0 : -1;
 
 	size = end - start;