Re: 2.6.13-rc6-mm1

Benoit Boissinot
2005-08-22T21:26:04Z

On Sun, Aug 21, 2005 at 06:34:48PM -0400, Jon Smirl wrote:
> This should fix it, but I'm not on a machine where I can test it. Can
> you give it a try and let me know?
>

it works ok.
But there is still at least one problem: if ops->store returns an error,
then there will be a substraction and the write will loop (i could do it
with a store wich returned EINVAL and a 22 length string).

I don't know if you can put a '\0' at buffer->page[count] if
count == PAGE_SIZE.

Moreover, i think it is more correct to add only the leading
whitespace from the count because if the ops->store doesn't read
everything it will do something weird:

For example, if we have ' 123 ' and ops->store read only one char,
then the function will return 7 (1 leading + 4 trailing + 1 read). For
the next call the buffer will be filled only by spaces which is
incorrect (it should be '23 ').

> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> --- a/fs/sysfs/file.c
> +++ b/fs/sysfs/file.c
> @@ -6,6 +6,7 @@
> #include <linux/fsnotify.h>
> #include <linux/kobject.h>
> #include <linux/namei.h>
> +#include <linux/ctype.h>
> #include <asm/uaccess.h>
> #include <asm/semaphore.h>
>
> @@ -207,8 +208,28 @@ flush_write_buffer(struct dentry * dentr
> struct attribute * attr = to_attr(dentry);
> struct kobject * kobj = to_kobj(dentry->d_parent);
> struct sysfs_ops * ops = buffer->ops;
> + int ws_count = count;
> + char *x;
>
> - return ops->store(kobj,attr,buffer->page,count);
> + /* locate trailing white space */
> + while ((count > 0) && isspace(buffer->page[count - 1]))
> + count--;
> +
> + /* locate leading white space */
> + x = buffer->page;
> + if (count > 0) {
> + while (isspace(*x))
> + x++;
> + count -= (x - buffer->page);
> + }
> + /* terminate the string */
> + x[count] = '\0';
what if count == PAGE_SIZE ?
> + ws_count -= count;
> +
> + if (count != 0)
> + count = ops->store(kobj, attr, x, count);
> +
> + return count + ws_count;
return (count < 0) ? count : count + ws_count;
> }
>
>
--