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sysfs: implement bin_buffer

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Implement bin_buffer which contains a mutex and pointer to PAGE_SIZE
buffer to properly synchronize accesses to per-openfile buffer and
prepare for immediate-kobj-disconnect.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Tejun Heo 2007-06-14 03:45:16 +09:00 committed by Greg Kroah-Hartman
parent 2b29ac252a
commit eb36165353
1 changed files with 50 additions and 16 deletions
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66
fs/sysfs/bin.c
View file

@ -20,6 +20,11 @@
#include "sysfs.h"
struct bin_buffer {
struct mutex mutex;
void *buffer;
};
static int
fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
{
@ -36,7 +41,7 @@ fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
static ssize_t
read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
{
char *buffer = file->private_data;
struct bin_buffer *bb = file->private_data;
struct dentry *dentry = file->f_path.dentry;
int size = dentry->d_inode->i_size;
loff_t offs = *off;
@ -49,17 +54,23 @@ read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
count = size - offs;
}
count = fill_read(dentry, buffer, offs, count);
if (count < 0)
return count;
mutex_lock(&bb->mutex);
if (copy_to_user(userbuf, buffer, count))
return -EFAULT;
count = fill_read(dentry, bb->buffer, offs, count);
if (count < 0)
goto out_unlock;
if (copy_to_user(userbuf, bb->buffer, count)) {
count = -EFAULT;
goto out_unlock;
}
pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
*off = offs + count;
out_unlock:
mutex_unlock(&bb->mutex);
return count;
}
@ -79,7 +90,7 @@ flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
static ssize_t write(struct file *file, const char __user *userbuf,
size_t bytes, loff_t *off)
{
char *buffer = file->private_data;
struct bin_buffer *bb = file->private_data;
struct dentry *dentry = file->f_path.dentry;
int size = dentry->d_inode->i_size;
loff_t offs = *off;
@ -92,25 +103,38 @@ static ssize_t write(struct file *file, const char __user *userbuf,
count = size - offs;
}
if (copy_from_user(buffer, userbuf, count))
return -EFAULT;
mutex_lock(&bb->mutex);
count = flush_write(dentry, buffer, offs, count);
if (copy_from_user(bb->buffer, userbuf, count)) {
count = -EFAULT;
goto out_unlock;
}
count = flush_write(dentry, bb->buffer, offs, count);
if (count > 0)
*off = offs + count;
out_unlock:
mutex_unlock(&bb->mutex);
return count;
}
static int mmap(struct file *file, struct vm_area_struct *vma)
{
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
struct kobject *kobj = to_kobj(file->f_path.dentry->d_parent);
int rc;
if (!attr->mmap)
return -EINVAL;
return attr->mmap(kobj, attr, vma);
mutex_lock(&bb->mutex);
rc = attr->mmap(kobj, attr, vma);
mutex_unlock(&bb->mutex);
return rc;
}
static int open(struct inode * inode, struct file * file)
@ -118,6 +142,7 @@ static int open(struct inode * inode, struct file * file)
struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
struct bin_buffer *bb = NULL;
int error = -EINVAL;
if (!kobj || !attr)
@ -135,14 +160,22 @@ static int open(struct inode * inode, struct file * file)
goto Error;
error = -ENOMEM;
file->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!file->private_data)
bb = kzalloc(sizeof(*bb), GFP_KERNEL);
if (!bb)
goto Error;
bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!bb->buffer)
goto Error;
mutex_init(&bb->mutex);
file->private_data = bb;
error = 0;
goto Done;
goto Done;
Error:
kfree(bb);
module_put(attr->attr.owner);
Done:
if (error)
@ -155,11 +188,12 @@ static int release(struct inode * inode, struct file * file)
struct kobject * kobj = to_kobj(file->f_path.dentry->d_parent);
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
u8 * buffer = file->private_data;
struct bin_buffer *bb = file->private_data;
kobject_put(kobj);
module_put(attr->attr.owner);
kfree(buffer);
kfree(bb->buffer);
kfree(bb);
return 0;
}