From: Simon Derr <Simon.Derr@bull.net>
Signed-off-by: Simon Derr <simon.derr@bull.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/fs/sysfs/file.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletion(-)
diff -puN fs/sysfs/file.c~possible-race-in-sysfs_read_file-and-sysfs_write_file-update fs/sysfs/file.c
--- 25/fs/sysfs/file.c~possible-race-in-sysfs_read_file-and-sysfs_write_file-update 2004-09-03 22:33:59.696647152 -0700
+++ 25-akpm/fs/sysfs/file.c 2004-09-03 22:33:59.700646544 -0700
@@ -55,6 +55,7 @@ struct sysfs_buffer {
char * page;
struct sysfs_ops * ops;
struct semaphore sem;
+ int needs_read_fill;
};
@@ -82,6 +83,7 @@ static int fill_read_buffer(struct dentr
return -ENOMEM;
count = ops->show(kobj,attr,buffer->page);
+ buffer->needs_read_fill = 0;
BUG_ON(count > (ssize_t)PAGE_SIZE);
if (count >= 0)
buffer->count = count;
@@ -146,7 +148,7 @@ sysfs_read_file(struct file *file, char
ssize_t retval = 0;
down(&buffer->sem);
- if ((!*ppos) || (!buffer->page)) {
+ if (buffer->needs_read_fill) {
if ((retval = fill_read_buffer(file->f_dentry,buffer)))
goto out;
}
@@ -182,6 +184,7 @@ fill_write_buffer(struct sysfs_buffer *
if (count >= PAGE_SIZE)
count = PAGE_SIZE - 1;
error = copy_from_user(buffer->page,buf,count);
+ buffer->needs_read_fill = 1;
return error ? -EFAULT : count;
}
@@ -299,6 +302,7 @@ static int check_perm(struct inode * ino
if (buffer) {
memset(buffer,0,sizeof(struct sysfs_buffer));
init_MUTEX(&buffer->sem);
+ buffer->needs_read_fill = 1;
buffer->ops = ops;
file->private_data = buffer;
} else
_