#include <linux/fs.h>
#include <linux/module.h>
#include <linux/slab.h>
+#include <linux/mutex.h>
#include <asm/uaccess.h>
-#include <asm/semaphore.h>
#include <linux/configfs.h>
#include "configfs_internal.h"
+/*
+ * A simple attribute can only be 4096 characters. Why 4k? Because the
+ * original code limited it to PAGE_SIZE. That's a bad idea, though,
+ * because an attribute of 16k on ia64 won't work on x86. So we limit to
+ * 4k, our minimum common page size.
+ */
+#define SIMPLE_ATTR_SIZE 4096
struct configfs_buffer {
size_t count;
loff_t pos;
char * page;
struct configfs_item_operations * ops;
- struct semaphore sem;
+ struct mutex mutex;
int needs_read_fill;
};
count = ops->show_attribute(item,attr,buffer->page);
buffer->needs_read_fill = 0;
- BUG_ON(count > (ssize_t)PAGE_SIZE);
+ BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
if (count >= 0)
buffer->count = count;
else
return ret;
}
-
-/**
- * flush_read_buffer - push buffer to userspace.
- * @buffer: data buffer for file.
- * @userbuf: user-passed buffer.
- * @count: number of bytes requested.
- * @ppos: file position.
- *
- * Copy the buffer we filled in fill_read_buffer() to userspace.
- * This is done at the reader's leisure, copying and advancing
- * the amount they specify each time.
- * This may be called continuously until the buffer is empty.
- */
-static int flush_read_buffer(struct configfs_buffer * buffer, char __user * buf,
- size_t count, loff_t * ppos)
-{
- int error;
-
- if (*ppos > buffer->count)
- return 0;
-
- if (count > (buffer->count - *ppos))
- count = buffer->count - *ppos;
-
- error = copy_to_user(buf,buffer->page + *ppos,count);
- if (!error)
- *ppos += count;
- return error ? -EFAULT : count;
-}
-
/**
* configfs_read_file - read an attribute.
* @file: file pointer.
struct configfs_buffer * buffer = file->private_data;
ssize_t retval = 0;
- down(&buffer->sem);
+ mutex_lock(&buffer->mutex);
if (buffer->needs_read_fill) {
if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
goto out;
}
pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
__FUNCTION__, count, *ppos, buffer->page);
- retval = flush_read_buffer(buffer,buf,count,ppos);
+ retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
+ buffer->count);
out:
- up(&buffer->sem);
+ mutex_unlock(&buffer->mutex);
return retval;
}
int error;
if (!buffer->page)
- buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
+ buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
if (!buffer->page)
return -ENOMEM;
- if (count > PAGE_SIZE)
- count = PAGE_SIZE;
+ if (count >= SIMPLE_ATTR_SIZE)
+ count = SIMPLE_ATTR_SIZE - 1;
error = copy_from_user(buffer->page,buf,count);
buffer->needs_read_fill = 1;
+ /* if buf is assumed to contain a string, terminate it by \0,
+ * so e.g. sscanf() can scan the string easily */
+ buffer->page[count] = 0;
return error ? -EFAULT : count;
}
struct configfs_buffer * buffer = file->private_data;
ssize_t len;
- down(&buffer->sem);
+ mutex_lock(&buffer->mutex);
len = fill_write_buffer(buffer, buf, count);
if (len > 0)
len = flush_write_buffer(file->f_path.dentry, buffer, count);
if (len > 0)
*ppos += len;
- up(&buffer->sem);
+ mutex_unlock(&buffer->mutex);
return len;
}
error = -ENOMEM;
goto Enomem;
}
- init_MUTEX(&buffer->sem);
+ mutex_init(&buffer->mutex);
buffer->needs_read_fill = 1;
buffer->ops = ops;
file->private_data = buffer;
if (buffer) {
if (buffer->page)
free_page((unsigned long)buffer->page);
+ mutex_destroy(&buffer->mutex);
kfree(buffer);
}
return 0;