linux-kernel - [PATCH 05/10] pstore: Convert "records

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Message-Id: <20200506152114.50375-6-keescook@chromium.org>
Date:   Wed,  6 May 2020 08:21:09 -0700
From:   Kees Cook <keescook@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Luis Henriques <lhenriques@...e.com>
Subject: [PATCH 05/10] pstore: Convert "records_list" locking to mutex

The pstorefs internal list lock doesn't need to be a spinlock and will
create problems when trying to access the list in the subsequent patch
that will walk the pstorefs records during pstore_unregister(). Change
this to a mutex to avoid may_sleep() warnings when unregistering devices.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 fs/pstore/inode.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 5cc09cb315f9..92ebcc75434f 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -22,14 +22,13 @@
 #include <linux/magic.h>
 #include <linux/pstore.h>
 #include <linux/slab.h>
-#include <linux/spinlock.h>
 #include <linux/uaccess.h>
 
 #include "internal.h"
 
 #define	PSTORE_NAMELEN	64
 
-static DEFINE_SPINLOCK(records_list_lock);
+static DEFINE_MUTEX(records_list_lock);
 static LIST_HEAD(records_list);
 
 struct pstore_private {
@@ -192,13 +191,12 @@ static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 static void pstore_evict_inode(struct inode *inode)
 {
 	struct pstore_private	*p = inode->i_private;
-	unsigned long		flags;
 
 	clear_inode(inode);
 	if (p) {
-		spin_lock_irqsave(&records_list_lock, flags);
+		mutex_lock(&records_list_lock);
 		list_del(&p->list);
-		spin_unlock_irqrestore(&records_list_lock, flags);
+		mutex_unlock(&records_list_lock);
 		free_pstore_private(p);
 	}
 }
@@ -297,12 +295,11 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 	int			rc = 0;
 	char			name[PSTORE_NAMELEN];
 	struct pstore_private	*private, *pos;
-	unsigned long		flags;
 	size_t			size = record->size + record->ecc_notice_size;
 
 	WARN_ON(!inode_is_locked(d_inode(root)));
 
-	spin_lock_irqsave(&records_list_lock, flags);
+	mutex_lock(&records_list_lock);
 	list_for_each_entry(pos, &records_list, list) {
 		if (pos->record->type == record->type &&
 		    pos->record->id == record->id &&
@@ -311,7 +308,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 			break;
 		}
 	}
-	spin_unlock_irqrestore(&records_list_lock, flags);
+	mutex_unlock(&records_list_lock);
 	if (rc)
 		return rc;
 
@@ -343,9 +340,9 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 
 	d_add(dentry, inode);
 
-	spin_lock_irqsave(&records_list_lock, flags);
+	mutex_lock(&records_list_lock);
 	list_add(&private->list, &records_list);
-	spin_unlock_irqrestore(&records_list_lock, flags);
+	mutex_unlock(&records_list_lock);
 
 	return 0;
 
-- 
2.20.1