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.

Link: https://lore.kernel.org/lkml/20200506152114.50375-6-keescook@chromium.org/
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 5cc09cb..92ebcc7 100644 (file)
--- 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;