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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: Alan 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Stern 2007-03-15 15:51:28 -04:00 committed by Linus Torvalds
parent d9a9cdfb07
commit e7b0d26a86
2 changed files with 12 additions and 8 deletions
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10
fs/sysfs/file.c
View File

@ -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",

10
fs/sysfs/inode.c
View File

@ -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);
}