linux-kernel - [PATCH V5 05/17] perf mmap: add new return value logic for perf_mmap__read

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Message-Id: <1516310792-208685-6-git-send-email-kan.liang@intel.com>
Date:   Thu, 18 Jan 2018 13:26:20 -0800
From:   kan.liang@...el.com
To:     acme@...nel.org, peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     wangnan0@...wei.com, jolsa@...nel.org, namhyung@...nel.org,
        ak@...ux.intel.com, yao.jin@...ux.intel.com,
        Kan Liang <kan.liang@...el.com>
Subject: [PATCH V5 05/17] perf mmap: add new return value logic for perf_mmap__read_init()

From: Kan Liang <kan.liang@...el.com>

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@...wei.com>
Signed-off-by: Kan Liang <kan.liang@...el.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;
 
-- 
2.5.5