linux-kernel - [PATCH -tip v2] locking/pvqspinlock: Robustify init_qspinlock

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Message-ID: <20160420041048.GA3472@linux-uzut.site>
Date:	Tue, 19 Apr 2016 21:10:48 -0700
From:	Davidlohr Bueso <dave@...olabs.net>
To:	"Long, Wai Man" <waiman.long@....com>
Cc:	"mingo@...nel.org" <mingo@...nel.org>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH -tip v2] locking/pvqspinlock: Robustify init_qspinlock_stat()

Specifically around the debugfs file creation calls,
I have no idea if they could ever possibly fail, but
this is core code (debug aside) so lets at least
check the return value and inform anything fishy.

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 kernel/locking/qspinlock_stat.h | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h
index 72722334237a..fa0863423a04 100644
--- a/kernel/locking/qspinlock_stat.h
+++ b/kernel/locking/qspinlock_stat.h
@@ -212,10 +212,8 @@ static int __init init_qspinlock_stat(void)
	struct dentry *d_qstat = debugfs_create_dir("qlockstat", NULL);
	int i;

-	if (!d_qstat) {
-		pr_warn("Could not create 'qlockstat' debugfs directory\n");
-		return 0;
-	}
+	if (!d_qstat)
+		goto out;

	/*
	 * Create the debugfs files
@@ -225,12 +223,20 @@ static int __init init_qspinlock_stat(void)
	 * performance.
	 */
	for (i = 0; i < qstat_num; i++)
-		debugfs_create_file(qstat_names[i], 0400, d_qstat,
-				   (void *)(long)i, &fops_qstat);
+		if (!debugfs_create_file(qstat_names[i], 0400, d_qstat,
+					 (void *)(long)i, &fops_qstat))
+			goto fail_undo;
+
+	if (!debugfs_create_file(qstat_names[qstat_reset_cnts], 0200, d_qstat,
+				 (void *)(long)qstat_reset_cnts, &fops_qstat))
+		goto fail_undo;

-	debugfs_create_file(qstat_names[qstat_reset_cnts], 0200, d_qstat,
-			   (void *)(long)qstat_reset_cnts, &fops_qstat);
	return 0;
+fail_undo:
+	debugfs_remove_recursive(d_qstat);
+out:
+	pr_info("Could not create 'qlockstat' debugfs entries\n");
+	return -ENOMEM;
 }
 fs_initcall(init_qspinlock_stat);

--
2.8.1