From e7b0d26a86943370c04d6833c6edba2a72a6e240 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Thu, 15 Mar 2007 15:51:28 -0400
Subject: [PATCH] [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>
---
fs/sysfs/file.c | 10 +++++-----
fs/sysfs/inode.c | 10 +++++++---
2 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 1bafdf6e171cb..fc4633378dc05 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -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",
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index ccb7d722c5589..4de5c6b899181 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -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);
}
--
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