[PATCH]Fix to the new sysfs bin file support

Rusty Lynch (rusty@linux.co.intel.com)
05 Mar 2003 18:38:42 -0800

I happen to notice the new binary file support in sysfs and had to take
for a spin. If I understand this correct my write file will need to
allocate the buffer->data, but then I have no way of freeing that memory
since I don't get a release callback.

Here is a patch that:
* makes sysfs cleanup the buffer->data allocated by the attribute write
* fixes a bug that causes the kernel to oops when somebody attempts to
write to the file.

BTW, would you be totally opposed to a patch that added open, release,
and ioctl to the list of functions supported by sysfs binary files?

Another question... How would a driver know that the various write and
read calls are coming from the same open, or would there be a way for a
driver to make it so that only one thing can open the sysfs file at a

--- fs/sysfs/bin.c.orig 2003-03-05 18:33:44.000000000 -0800
+++ fs/sysfs/bin.c 2003-03-05 18:34:01.000000000 -0800
@@ -50,6 +50,10 @@
ret = count;
+ if (buffer && buffer->data) {
+ kfree(buffer->data);
+ buffer->data = NULL;
+ }
return ret;

@@ -66,7 +70,7 @@
static int fill_write(struct file * file, const char * userbuf,
struct sysfs_bin_buffer * buffer)
- return copy_from_user(buffer,userbuf,buffer->count) ?
+ return copy_from_user(buffer->data,userbuf,buffer->count) ?
-EFAULT : 0;

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