linux-kernel - Re: sysfs: use a separate locking class for open files depending on mmap

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Message-ID: <20131203221543.GP8277@htj.dyndns.org>
Date:	Tue, 3 Dec 2013 17:15:43 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Dave Jones <davej@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	gregkh@...uxfoundation.org
Subject: Re: sysfs: use a separate locking class for open files depending on
 mmap

Hello,

Can you please test whether this patch makes the lockdep warning go
away?

Thanks a lot!

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index b94f936..fccb645 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -470,6 +470,9 @@ static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
 	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
 	int rc;
 
+	if (!(of->sd->s_flags & SYSFS_FLAG_HAS_MMAP))
+		return -ENODEV;
+
 	mutex_lock(&of->mutex);
 
 	/* need of->sd for battr, its parent for kobj */
@@ -477,9 +480,6 @@ static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
 	if (!sysfs_get_active(of->sd))
 		goto out_unlock;
 
-	if (!battr->mmap)
-		goto out_put;
-
 	rc = battr->mmap(file, kobj, battr, vma);
 	if (rc)
 		goto out_put;
@@ -851,6 +851,14 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
 	sd->s_attr.attr = (void *)attr;
 	sysfs_dirent_init_lockdep(sd);
 
+	if (type == SYSFS_KOBJ_BIN_ATTR) {
+		const struct bin_attribute *battr =
+			container_of(attr, struct bin_attribute, attr);
+
+		if (battr->mmap)
+			sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
+	}
+
 	sysfs_addrm_start(&acxt);
 	rc = sysfs_add_one(&acxt, sd, dir_sd);
 	sysfs_addrm_finish(&acxt);
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 0af09fb..27c1f7e 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -96,6 +96,7 @@ struct sysfs_dirent {
 
 #define SYSFS_FLAG_MASK			~(SYSFS_NS_TYPE_MASK|SYSFS_TYPE_MASK)
 #define SYSFS_FLAG_REMOVED		0x02000
+#define SYSFS_FLAG_HAS_MMAP		0x04000
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 {

-- 
tejun
--
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