10 files changed, 81 insertions, 15 deletions

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 8fa8deab6449..4b7b4522b64f 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -1,10 +1,10 @@
 menu "Generic Driver Options"
 
-config UEVENT_HELPER_PATH
-        string "path to uevent helper"
-        default ""
+config UEVENT_HELPER
+        bool "Support for uevent helper"
+        default y
         help
-          Path to uevent helper program forked by the kernel for
+          The uevent helper program is forked by the kernel for
           every uevent.
           Before the switch to the netlink-based uevent source, this was
           used to hook hotplug scripts into kernel device events. It
@@ -15,8 +15,13 @@ config UEVENT_HELPER_PATH
           that it creates a high system load, or on smaller systems
           it is known to create out-of-memory situations during bootup.
 
-          To disable user space helper program execution at early boot
-          time specify an empty string here. This setting can be altered
+config UEVENT_HELPER_PATH
+        string "path to uevent helper"
+        depends on UEVENT_HELPER
+        default ""
+        help
+          To disable user space helper program execution at by default
+          specify an empty string here. This setting can still be altered
           via /proc/sys/kernel/hotplug or via /sys/kernel/uevent_helper
           later at runtime.
 
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index ac127cd008bf..a693f5b01ae6 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -714,6 +714,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
                 return ERR_PTR(-ENOMEM);
 
         ida_init(&root->ino_ida);
+        INIT_LIST_HEAD(&root->supers);
 
         kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
                                KERNFS_DIR);
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index e01ea4a14a01..40251cd741a0 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -14,6 +14,7 @@
 #include <linux/poll.h>
 #include <linux/pagemap.h>
 #include <linux/sched.h>
+#include <linux/fsnotify.h>
 
 #include "kernfs-internal.h"
 
@@ -787,20 +788,48 @@ static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait)
  */
 void kernfs_notify(struct kernfs_node *kn)
 {
+        struct kernfs_root *root = kernfs_root(kn);
         struct kernfs_open_node *on;
+        struct kernfs_super_info *info;
         unsigned long flags;
 
+        if (WARN_ON(kernfs_type(kn) != KERNFS_FILE))
+                return;
+
+        /* kick poll */
         spin_lock_irqsave(&kernfs_open_node_lock, flags);
 
-        if (!WARN_ON(kernfs_type(kn) != KERNFS_FILE)) {
-                on = kn->attr.open;
-                if (on) {
-                        atomic_inc(&on->event);
-                        wake_up_interruptible(&on->poll);
-                }
+        on = kn->attr.open;
+        if (on) {
+                atomic_inc(&on->event);
+                wake_up_interruptible(&on->poll);
         }
 
         spin_unlock_irqrestore(&kernfs_open_node_lock, flags);
+
+        /* kick fsnotify */
+        mutex_lock(&kernfs_mutex);
+
+        list_for_each_entry(info, &root->supers, node) {
+                struct inode *inode;
+                struct dentry *dentry;
+
+                inode = ilookup(info->sb, kn->ino);
+                if (!inode)
+                        continue;
+
+                dentry = d_find_any_alias(inode);
+                if (dentry) {
+                        fsnotify_parent(NULL, dentry, FS_MODIFY);
+                        fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
+                                 NULL, 0);
+                        dput(dentry);
+                }
+
+                iput(inode);
+        }
+
+        mutex_unlock(&kernfs_mutex);
 }
 EXPORT_SYMBOL_GPL(kernfs_notify);
 
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 8be13b2a079b..dc84a3ef9ca2 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -49,6 +49,8 @@ static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn)
  * mount.c
  */
 struct kernfs_super_info {
+        struct super_block      *sb;
+
         /*
          * The root associated with this super_block.  Each super_block is
          * identified by the root and ns it's associated with.
@@ -62,6 +64,9 @@ struct kernfs_super_info {
          * an array and compare kernfs_node tag against every entry.
          */
         const void              *ns;
+
+        /* anchored at kernfs_root->supers, protected by kernfs_mutex */
+        struct list_head        node;
 };
 #define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
 
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 6a5f04ac8704..f25a7c0c3cdc 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -68,6 +68,7 @@ static int kernfs_fill_super(struct super_block *sb)
         struct inode *inode;
         struct dentry *root;
 
+        info->sb = sb;
         sb->s_blocksize = PAGE_CACHE_SIZE;
         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
         sb->s_magic = SYSFS_MAGIC;
@@ -166,12 +167,18 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
                 *new_sb_created = !sb->s_root;
 
         if (!sb->s_root) {
+                struct kernfs_super_info *info = kernfs_info(sb);
+
                 error = kernfs_fill_super(sb);
                 if (error) {
                         deactivate_locked_super(sb);
                         return ERR_PTR(error);
                 }
                 sb->s_flags |= MS_ACTIVE;
+
+                mutex_lock(&kernfs_mutex);
+                list_add(&info->node, &root->supers);
+                mutex_unlock(&kernfs_mutex);
         }
 
         return dget(sb->s_root);
@@ -190,6 +197,10 @@ void kernfs_kill_sb(struct super_block *sb)
         struct kernfs_super_info *info = kernfs_info(sb);
         struct kernfs_node *root_kn = sb->s_root->d_fsdata;
 
+        mutex_lock(&kernfs_mutex);
+        list_del(&info->node);
+        mutex_unlock(&kernfs_mutex);
+
         /*
          * Remove the superblock from fs_supers/s_instances
          * so we can't find it, before freeing kernfs_super_info.
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index b0122dc6f96a..589318b73e61 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -144,6 +144,10 @@ struct kernfs_root {
         /* private fields, do not use outside kernfs proper */
         struct ida              ino_ida;
         struct kernfs_syscall_ops *syscall_ops;
+
+        /* list of kernfs_super_info of this root, protected by kernfs_mutex */
+        struct list_head        supers;
+
         wait_queue_head_t       deactivate_waitq;
 };
 
diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index f896a33e8341..2d61b909f414 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -32,8 +32,10 @@
 #define UEVENT_NUM_ENVP                 32      /* number of env pointers */
 #define UEVENT_BUFFER_SIZE              2048    /* buffer for the variables */
 
+#ifdef CONFIG_UEVENT_HELPER
 /* path to the userspace helper executed on an event */
 extern char uevent_helper[];
+#endif
 
 /* counter to tag the uevent, read only except for the kobject core */
 extern u64 uevent_seqnum;
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 2495a9b14ac8..6683ccef9fff 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -37,6 +37,7 @@ static ssize_t uevent_seqnum_show(struct kobject *kobj,
 }
 KERNEL_ATTR_RO(uevent_seqnum);
 
+#ifdef CONFIG_UEVENT_HELPER
 /* uevent helper program, used during early boot */
 static ssize_t uevent_helper_show(struct kobject *kobj,
                                   struct kobj_attribute *attr, char *buf)
@@ -56,7 +57,7 @@ static ssize_t uevent_helper_store(struct kobject *kobj,
         return count;
 }
 KERNEL_ATTR_RW(uevent_helper);
-
+#endif
 
 #ifdef CONFIG_PROFILING
 static ssize_t profiling_show(struct kobject *kobj,
@@ -189,7 +190,9 @@ EXPORT_SYMBOL_GPL(kernel_kobj);
 static struct attribute * kernel_attrs[] = {
         &fscaps_attr.attr,
         &uevent_seqnum_attr.attr,
+#ifdef CONFIG_UEVENT_HELPER
         &uevent_helper_attr.attr,
+#endif
 #ifdef CONFIG_PROFILING
         &profiling_attr.attr,
 #endif
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 74f5b580fe34..bc966a8ffc3e 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -643,7 +643,7 @@ static struct ctl_table kern_table[] = {
                 .extra2         = &one,
         },
 #endif
-
+#ifdef CONFIG_UEVENT_HELPER
         {
                 .procname       = "hotplug",
                 .data           = &uevent_helper,
@@ -651,7 +651,7 @@ static struct ctl_table kern_table[] = {
                 .mode           = 0644,
                 .proc_handler   = proc_dostring,
         },
-
+#endif
 #ifdef CONFIG_CHR_DEV_SG
         {
                 .procname       = "sg-big-buff",
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 4e3bd71bd949..9ebf9e20de53 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -29,7 +29,9 @@
 
 
 u64 uevent_seqnum;
+#ifdef CONFIG_UEVENT_HELPER
 char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
+#endif
 #ifdef CONFIG_NET
 struct uevent_sock {
         struct list_head list;
@@ -109,6 +111,7 @@ static int kobj_bcast_filter(struct sock *dsk, struct sk_buff *skb, void *data)
 }
 #endif
 
+#ifdef CONFIG_UEVENT_HELPER
 static int kobj_usermode_filter(struct kobject *kobj)
 {
         const struct kobj_ns_type_operations *ops;
@@ -147,6 +150,7 @@ static void cleanup_uevent_env(struct subprocess_info *info)
 {
         kfree(info->data);
 }
+#endif
 
 /**
  * kobject_uevent_env - send an uevent with environmental data
@@ -323,6 +327,7 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 #endif
         mutex_unlock(&uevent_sock_mutex);
 
+#ifdef CONFIG_UEVENT_HELPER
         /* call uevent_helper, usually only enabled during early boot */
         if (uevent_helper[0] && !kobj_usermode_filter(kobj)) {
                 struct subprocess_info *info;
@@ -347,6 +352,7 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
                         env = NULL;     /* freed by cleanup_uevent_env */
                 }
         }
+#endif
 
 exit:
         kfree(devpath);