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authorOliver Neukum <oliver@neukum.org>2006-12-20 10:52:44 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2007-02-07 10:37:13 -0800
commit94bebf4d1b8e7719f0f3944c037a21cfd99a4af7 (patch)
tree25c6ba1836e74f608b4e434b4f0f4d5c28b11de1 /fs/sysfs/inode.c
parentcb986b749c7178422bfbc982cd30e04d5db54bbc (diff)
Driver core: fix race in sysfs between sysfs_remove_file() and read()/write()
This patch prevents a race between IO and removing a file from sysfs. It introduces a list of sysfs_buffers associated with a file at the inode. Upon removal of a file the list is walked and the buffers marked orphaned. IO to orphaned buffers fails with -ENODEV. The driver can safely free associated data structures or be unloaded. Signed-off-by: Oliver Neukum <oliver@neukum.name> Acked-by: Maneesh Soni <maneesh@in.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/sysfs/inode.c')
-rw-r--r--fs/sysfs/inode.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index e79e38d52c0..1a81ebce20e 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -13,6 +13,7 @@
#include <linux/backing-dev.h>
#include <linux/capability.h>
#include <linux/errno.h>
+#include <asm/semaphore.h>
#include "sysfs.h"
extern struct super_block * sysfs_sb;
@@ -209,6 +210,22 @@ const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
return NULL;
}
+static inline void orphan_all_buffers(struct inode *node)
+{
+ struct sysfs_buffer_collection *set = node->i_private;
+ struct sysfs_buffer *buf;
+
+ mutex_lock(&node->i_mutex);
+ if (node->i_private) {
+ list_for_each_entry(buf, &set->associates, associates) {
+ down(&buf->sem);
+ buf->orphaned = 1;
+ up(&buf->sem);
+ }
+ }
+ mutex_unlock(&node->i_mutex);
+}
+
/*
* Unhashes the dentry corresponding to given sysfs_dirent
@@ -217,16 +234,23 @@ const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
{
struct dentry * dentry = sd->s_dentry;
+ struct inode *inode;
if (dentry) {
spin_lock(&dcache_lock);
spin_lock(&dentry->d_lock);
if (!(d_unhashed(dentry) && dentry->d_inode)) {
+ inode = dentry->d_inode;
+ spin_lock(&inode->i_lock);
+ __iget(inode);
+ spin_unlock(&inode->i_lock);
dget_locked(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
simple_unlink(parent->d_inode, dentry);
+ orphan_all_buffers(inode);
+ iput(inode);
} else {
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);