linux-kernel - [PATCH 2/3] gcov: simplify buffer allocation

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Message-Id: <20210315235453.b6de4a92096e.Iac40a5166589cefbff8449e466bd1b38ea7a17af@changeid>
Date:   Mon, 15 Mar 2021 23:54:54 +0100
From:   Johannes Berg <johannes@...solutions.net>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Oberparleiter <oberpar@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH 2/3] gcov: simplify buffer allocation

From: Johannes Berg <johannes.berg@...el.com>

Use just a single vmalloc() with struct_size() instead of
a separate kmalloc() for the iter struct.

Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
 kernel/gcov/fs.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/kernel/gcov/fs.c b/kernel/gcov/fs.c
index 2d29e1d1225d..40ea81c0475b 100644
--- a/kernel/gcov/fs.c
+++ b/kernel/gcov/fs.c
@@ -97,9 +97,9 @@ __setup("gcov_persist=", gcov_persist_setup);
  */
 struct gcov_iterator {
 	struct gcov_info *info;
-	void *buffer;
 	size_t size;
 	loff_t pos;
+	char buffer[];
 };
 
 /**
@@ -111,25 +111,20 @@ struct gcov_iterator {
 static struct gcov_iterator *gcov_iter_new(struct gcov_info *info)
 {
 	struct gcov_iterator *iter;
+	size_t size;
+
+	/* Dry-run to get the actual buffer size. */
+	size = convert_to_gcda(NULL, info);
 
-	iter = kzalloc(sizeof(struct gcov_iterator), GFP_KERNEL);
+	iter = vmalloc(struct_size(iter, buffer, size));
 	if (!iter)
-		goto err_free;
+		return NULL;
 
 	iter->info = info;
-	/* Dry-run to get the actual buffer size. */
-	iter->size = convert_to_gcda(NULL, info);
-	iter->buffer = vmalloc(iter->size);
-	if (!iter->buffer)
-		goto err_free;
-
+	iter->size = size;
 	convert_to_gcda(iter->buffer, info);
 
 	return iter;
-
-err_free:
-	kfree(iter);
-	return NULL;
 }
 
 
@@ -139,8 +134,7 @@ static struct gcov_iterator *gcov_iter_new(struct gcov_info *info)
  */
 static void gcov_iter_free(struct gcov_iterator *iter)
 {
-	vfree(iter->buffer);
-	kfree(iter);
+	vfree(iter);
 }
 
 /**
-- 
2.30.2