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Commit e7b0d26a authored by Alan Stern's avatar Alan Stern Committed by Linus Torvalds
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[PATCH] sysfs: reinstate exclusion between method calls and attribute unregistration 



This patch (as869) reinstates the mutual exclusion between sysfs
attribute method calls and attribute unregistration.  The
previously-reported deadlocks have been fixed, and this exclusion is
by far the simplest way to avoid races during driver unbinding.

The check for orphaned read-buffers has been moved down slightly, so
that the remainder of a partially-read buffer will still be available
to userspace even after the attribute has been unregistered.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d9a9cdfb

fs/sysfs/file.c

+5 −5
Original line number Diff line number Diff line
@@ -168,12 +168,12 @@ sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) 
	ssize_t retval = 0;



	down(&buffer->sem);

	if (buffer->orphaned) {

		retval = -ENODEV;

		goto out;

	}

	if (buffer->needs_read_fill) {

		if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))

		if (buffer->orphaned)

			retval = -ENODEV;

		else

			retval = fill_read_buffer(file->f_path.dentry,buffer);

		if (retval)

			goto out;

	}

	pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",

fs/sysfs/inode.c

+7 −3
Original line number Diff line number Diff line
@@ -222,13 +222,17 @@ const unsigned char * sysfs_get_name(struct sysfs_dirent *sd) 


static inline void orphan_all_buffers(struct inode *node)

{

	struct sysfs_buffer_collection *set = node->i_private;

	struct sysfs_buffer_collection *set;

	struct sysfs_buffer *buf;



	mutex_lock_nested(&node->i_mutex, I_MUTEX_CHILD);

	if (node->i_private) {

		list_for_each_entry(buf, &set->associates, associates)

	set = node->i_private;

	if (set) {

		list_for_each_entry(buf, &set->associates, associates) {

			down(&buf->sem);

			buf->orphaned = 1;

			up(&buf->sem);

		}

	}

	mutex_unlock(&node->i_mutex);

}