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add mmap support to struct bin_attribute files

PATCH In review Jesse Barnes 2 participants 3 messages Dec 21, 2004 Driver core

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Jesse Barnes

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#0 lore raw

PATCH 1/1 add mmap support to struct bin_attribute files

This patch adds an mmap method and some more error checking to struct bin_attribute--good for things like exporting PCI resources directly. I wasn't sure about the return values for the case where an attribute is missing a given method, and it looks like mm.h can't be included in sysfs.h, so I had to forward declare struct vm_area_struct. Other than that, it works fine for my test cases.

 fs/sysfs/bin.c        |   27 +++++++++++++++++++++++++--
 include/linux/sysfs.h |    6 ++++++
 2 files changed, 31 insertions(+), 2 deletions(-)
Signed-off-by Jesse Barnes <[email protected]>

Thanks,
Jesse

===== include/linux/sysfs.h 1.38 vs edited =====

include/linux/sysfs.h +6 -0
@@ -2,6 +2,7 @@
  * sysfs.h - definitions for the device driver filesystem
  *
  * Copyright (c) 2001,2002 Patrick Mochel
+ * Copyright (c) 2004 Silicon Graphics, Inc.
  *
  * Please see Documentation/filesystems/sysfs.txt for more information.
  */

@@ -47,11 +48,16 @@
 
 #define attr_name(_attr) (_attr).attr.name
 
+struct vm_area_struct; /* circular dependencies? */
+
 struct bin_attribute {
 	struct attribute	attr;
 	size_t			size;
+	void			*private;
 	ssize_t (*read)(struct kobject *, char *, loff_t, size_t);
 	ssize_t (*write)(struct kobject *, char *, loff_t, size_t);
+	int (*mmap)(struct kobject *, struct bin_attribute *attr,
+		    struct vm_area_struct *vma);
 };
 
 struct sysfs_ops {

===== fs/sysfs/bin.c 1.19 vs edited =====

fs/sysfs/bin.c +25 -2
@@ -1,5 +1,9 @@
 /*
  * bin.c - binary file operations for sysfs.
+ *
+ * Copyright (c) 2003 Patrick Mochel
+ * Copyright (c) 2003 Matthew Wilcox
+ * Copyright (c) 2004 Silicon Graphics, Inc.
  */
 
 #undef DEBUG

@@ -20,6 +24,9 @@
 	struct bin_attribute * attr = to_bin_attr(dentry);
 	struct kobject * kobj = to_kobj(dentry->d_parent);
 
+	if (!attr->read)
+		return -EINVAL;
+
 	return attr->read(kobj, buffer, off, count);
 }
 

@@ -63,6 +70,9 @@
 	struct bin_attribute *attr = to_bin_attr(dentry);
 	struct kobject *kobj = to_kobj(dentry->d_parent);
 
+	if (!attr->write)
+		return -EINVAL;
+
 	return attr->write(kobj, buffer, offset, count);
 }
 

@@ -92,6 +102,18 @@
 	return count;
 }
 
+static int mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct dentry *dentry = file->f_dentry;
+	struct bin_attribute *attr = to_bin_attr(dentry);
+	struct kobject *kobj = to_kobj(dentry->d_parent);
+
+	if (!attr->mmap)
+		return -EINVAL;
+
+	return attr->mmap(kobj, attr, vma);
+}
+
 static int open(struct inode * inode, struct file * file)
 {
 	struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);

@@ -107,9 +129,9 @@
 		goto Done;
 
 	error = -EACCES;
-	if ((file->f_mode & FMODE_WRITE) && !attr->write)
+	if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
 		goto Error;
-	if ((file->f_mode & FMODE_READ) && !attr->read)
+	if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
 		goto Error;
 
 	error = -ENOMEM;

@@ -144,6 +166,7 @@
 struct file_operations bin_fops = {
 	.read		= read,
 	.write		= write,
+	.mmap		= mmap,
 	.llseek		= generic_file_llseek,
 	.open		= open,
 	.release	= release,
#1 lore raw
Quoted 2 lines · Jesse Barnes

* Copyright (c) 2001,2002 Patrick Mochel
+ * Copyright (c) 2004 Silicon Graphics, Inc.

Minor nit, some copyright lawyers I know say it should be (C) not (c), for what it's worth...

Quoted 1 line

+struct vm_area_struct; /* circular dependencies? */

Drop the comment :)

include/linux/sysfs.h line 56

Quoted 4 lines

struct bin_attribute {

include/linux/sysfs.h +1 -0
 	struct attribute	attr;
 	size_t			size;
+	void			*private;

Why the private pointer? Don't you get everything you need in the kobject itself?

thanks,

greg k-h

#2 lore raw
In reply to Jesse Barnes
Quoted 7 lines · Jesse Barnes

This patch adds an mmap method and some more error checking to struct bin_attribute--good for things like exporting PCI resources directly. I wasn't sure about the return values for the case where an attribute is missing a given method, and it looks like mm.h can't be included in sysfs.h, so I had to forward declare struct vm_area_struct. Other than that, it works fine for my test cases.

Quoted 5 lines
 fs/sysfs/bin.c        |   27 +++++++++++++++++++++++++--
 include/linux/sysfs.h |    6 ++++++
 2 files changed, 31 insertions(+), 2 deletions(-)
Signed-off-by Jesse Barnes <[email protected]>

Nice, thanks for doing this. I've applied it to my trees.

greg k-h