3 files changed, 55 insertions, 45 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 4a13e5a01ce3..61071fecc82e 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -147,7 +147,7 @@ config IRQSOFF_TRACER
           disabled by default and can be runtime (re-)started
           via:
 
-              echo 0 > /debugfs/tracing/tracing_max_latency
+              echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 
           (Note that kernel size and overhead increases with this option
           enabled. This option and the preempt-off timing option can be
@@ -168,7 +168,7 @@ config PREEMPT_TRACER
           disabled by default and can be runtime (re-)started
           via:
 
-              echo 0 > /debugfs/tracing/tracing_max_latency
+              echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 
           (Note that kernel size and overhead increases with this option
           enabled. This option and the irqs-off timing option can be
@@ -261,7 +261,7 @@ config PROFILE_ANNOTATED_BRANCHES
           This tracer profiles all the the likely and unlikely macros
           in the kernel. It will display the results in:
 
-          /debugfs/tracing/profile_annotated_branch
+          /sys/kernel/debug/tracing/profile_annotated_branch
 
           Note: this will add a significant overhead, only turn this
           on if you need to profile the system's use of these macros.
@@ -274,7 +274,7 @@ config PROFILE_ALL_BRANCHES
           taken in the kernel is recorded whether it hit or miss.
           The results will be displayed in:
 
-          /debugfs/tracing/profile_branch
+          /sys/kernel/debug/tracing/profile_branch
 
           This option also enables the likely/unlikely profiler.
 
@@ -323,7 +323,7 @@ config STACK_TRACER
         select KALLSYMS
         help
           This special tracer records the maximum stack footprint of the
-          kernel and displays it in debugfs/tracing/stack_trace.
+          kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
 
           This tracer works by hooking into every function call that the
           kernel executes, and keeping a maximum stack depth value and
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8acd9b81a5d7..c1878bfb2e1e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -344,7 +344,7 @@ static raw_spinlock_t ftrace_max_lock =
 /*
  * Copy the new maximum trace into the separate maximum-trace
  * structure. (this way the maximum trace is permanently saved,
- * for later retrieval via /debugfs/tracing/latency_trace)
+ * for later retrieval via /sys/kernel/debug/tracing/latency_trace)
  */
 static void
 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
@@ -2414,21 +2414,20 @@ static const struct file_operations tracing_iter_fops = {
 
 static const char readme_msg[] =
         "tracing mini-HOWTO:\n\n"
-        "# mkdir /debug\n"
-        "# mount -t debugfs nodev /debug\n\n"
-        "# cat /debug/tracing/available_tracers\n"
+        "# mount -t debugfs nodev /sys/kernel/debug\n\n"
+        "# cat /sys/kernel/debug/tracing/available_tracers\n"
         "wakeup preemptirqsoff preemptoff irqsoff function sched_switch nop\n\n"
-        "# cat /debug/tracing/current_tracer\n"
+        "# cat /sys/kernel/debug/tracing/current_tracer\n"
         "nop\n"
-        "# echo sched_switch > /debug/tracing/current_tracer\n"
-        "# cat /debug/tracing/current_tracer\n"
+        "# echo sched_switch > /sys/kernel/debug/tracing/current_tracer\n"
+        "# cat /sys/kernel/debug/tracing/current_tracer\n"
         "sched_switch\n"
-        "# cat /debug/tracing/trace_options\n"
+        "# cat /sys/kernel/debug/tracing/trace_options\n"
         "noprint-parent nosym-offset nosym-addr noverbose\n"
-        "# echo print-parent > /debug/tracing/trace_options\n"
-        "# echo 1 > /debug/tracing/tracing_enabled\n"
-        "# cat /debug/tracing/trace > /tmp/trace.txt\n"
-        "# echo 0 > /debug/tracing/tracing_enabled\n"
+        "# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
+        "# echo 1 > /sys/kernel/debug/tracing/tracing_enabled\n"
+        "# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
+        "# echo 0 > /sys/kernel/debug/tracing/tracing_enabled\n"
 ;
 
 static ssize_t
diff --git a/kernel/user.c b/kernel/user.c
index 850e0ba41c1e..2c000e7132ac 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -75,21 +75,6 @@ static void uid_hash_remove(struct user_struct *up)
         put_user_ns(up->user_ns);
 }
 
-static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
-{
-        struct user_struct *user;
-        struct hlist_node *h;
-
-        hlist_for_each_entry(user, h, hashent, uidhash_node) {
-                if (user->uid == uid) {
-                        atomic_inc(&user->__count);
-                        return user;
-                }
-        }
-
-        return NULL;
-}
-
 #ifdef CONFIG_USER_SCHED
 
 static void sched_destroy_user(struct user_struct *up)
@@ -119,6 +104,23 @@ static int sched_create_user(struct user_struct *up) { return 0; }
 
 #if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS)
 
+static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
+{
+        struct user_struct *user;
+        struct hlist_node *h;
+
+        hlist_for_each_entry(user, h, hashent, uidhash_node) {
+                if (user->uid == uid) {
+                        /* possibly resurrect an "almost deleted" object */
+                        if (atomic_inc_return(&user->__count) == 1)
+                                cancel_delayed_work(&user->work);
+                        return user;
+                }
+        }
+
+        return NULL;
+}
+
 static struct kset *uids_kset; /* represents the /sys/kernel/uids/ directory */
 static DEFINE_MUTEX(uids_mutex);
 
@@ -283,12 +285,12 @@ int __init uids_sysfs_init(void)
         return uids_user_create(&root_user);
 }
 
-/* work function to remove sysfs directory for a user and free up
+/* delayed work function to remove sysfs directory for a user and free up
  * corresponding structures.
  */
 static void cleanup_user_struct(struct work_struct *w)
 {
-        struct user_struct *up = container_of(w, struct user_struct, work);
+        struct user_struct *up = container_of(w, struct user_struct, work.work);
         unsigned long flags;
         int remove_user = 0;
 
@@ -297,15 +299,12 @@ static void cleanup_user_struct(struct work_struct *w)
          */
         uids_mutex_lock();
 
-        local_irq_save(flags);
-
-        if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
+        spin_lock_irqsave(&uidhash_lock, flags);
+        if (atomic_read(&up->__count) == 0) {
                 uid_hash_remove(up);
                 remove_user = 1;
-                spin_unlock_irqrestore(&uidhash_lock, flags);
-        } else {
-                local_irq_restore(flags);
         }
+        spin_unlock_irqrestore(&uidhash_lock, flags);
 
         if (!remove_user)
                 goto done;
@@ -331,16 +330,28 @@ done:
  */
 static void free_user(struct user_struct *up, unsigned long flags)
 {
-        /* restore back the count */
-        atomic_inc(&up->__count);
         spin_unlock_irqrestore(&uidhash_lock, flags);
-
-        INIT_WORK(&up->work, cleanup_user_struct);
-        schedule_work(&up->work);
+        INIT_DELAYED_WORK(&up->work, cleanup_user_struct);
+        schedule_delayed_work(&up->work, msecs_to_jiffies(1000));
 }
 
 #else   /* CONFIG_USER_SCHED && CONFIG_SYSFS */
 
+static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
+{
+        struct user_struct *user;
+        struct hlist_node *h;
+
+        hlist_for_each_entry(user, h, hashent, uidhash_node) {
+                if (user->uid == uid) {
+                        atomic_inc(&user->__count);
+                        return user;
+                }
+        }
+
+        return NULL;
+}
+
 int uids_sysfs_init(void) { return 0; }
 static inline int uids_user_create(struct user_struct *up) { return 0; }
 static inline void uids_mutex_lock(void) { }