Merge tag 'trace-fixes-v3.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "This includes a fix to a memory leak when adding filters to traces.

  Also, Masami Hiramatsu fixed up some minor bugs that were discovered
  by sparse."

* tag 'trace-fixes-v3.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing/kprobes: Make print_*probe_event static
  tracing/kprobes: Fix a sparse warning for incorrect type in assignment
  tracing/kprobes: Use rcu_dereference_raw for tp->files
  tracing: Fix leaks of filter preds

2 files changed, 44 insertions, 13 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index a6361178de5a..e1b653f7e1ca 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -750,7 +750,11 @@ static int filter_set_pred(struct event_filter *filter,
 
 static void __free_preds(struct event_filter *filter)
 {
+        int i;
+
         if (filter->preds) {
+                for (i = 0; i < filter->n_preds; i++)
+                        kfree(filter->preds[i].ops);
                 kfree(filter->preds);
                 filter->preds = NULL;
         }
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 636d45fe69b3..9f46e98ba8f2 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -35,7 +35,7 @@ struct trace_probe {
         const char              *symbol;        /* symbol name */
         struct ftrace_event_class       class;
         struct ftrace_event_call        call;
-        struct ftrace_event_file        **files;
+        struct ftrace_event_file * __rcu *files;
         ssize_t                 size;           /* trace entry size */
         unsigned int            nr_args;
         struct probe_arg        args[];
@@ -185,9 +185,14 @@ static struct trace_probe *find_trace_probe(const char *event,
 
 static int trace_probe_nr_files(struct trace_probe *tp)
 {
-        struct ftrace_event_file **file = tp->files;
+        struct ftrace_event_file **file;
         int ret = 0;
 
+        /*
+         * Since all tp->files updater is protected by probe_enable_lock,
+         * we don't need to lock an rcu_read_lock.
+         */
+        file = rcu_dereference_raw(tp->files);
         if (file)
                 while (*(file++))
                         ret++;
@@ -209,9 +214,10 @@ enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
         mutex_lock(&probe_enable_lock);
 
         if (file) {
-                struct ftrace_event_file **new, **old = tp->files;
+                struct ftrace_event_file **new, **old;
                 int n = trace_probe_nr_files(tp);
 
+                old = rcu_dereference_raw(tp->files);
                 /* 1 is for new one and 1 is for stopper */
                 new = kzalloc((n + 2) * sizeof(struct ftrace_event_file *),
                               GFP_KERNEL);
@@ -251,11 +257,17 @@ enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
 static int
 trace_probe_file_index(struct trace_probe *tp, struct ftrace_event_file *file)
 {
+        struct ftrace_event_file **files;
         int i;
 
-        if (tp->files) {
-                for (i = 0; tp->files[i]; i++)
-                        if (tp->files[i] == file)
+        /*
+         * Since all tp->files updater is protected by probe_enable_lock,
+         * we don't need to lock an rcu_read_lock.
+         */
+        files = rcu_dereference_raw(tp->files);
+        if (files) {
+                for (i = 0; files[i]; i++)
+                        if (files[i] == file)
                                 return i;
         }
 
@@ -274,10 +286,11 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
         mutex_lock(&probe_enable_lock);
 
         if (file) {
-                struct ftrace_event_file **new, **old = tp->files;
+                struct ftrace_event_file **new, **old;
                 int n = trace_probe_nr_files(tp);
                 int i, j;
 
+                old = rcu_dereference_raw(tp->files);
                 if (n == 0 || trace_probe_file_index(tp, file) < 0) {
                         ret = -EINVAL;
                         goto out_unlock;
@@ -872,9 +885,16 @@ __kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs,
 static __kprobes void
 kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
 {
-        struct ftrace_event_file **file = tp->files;
+        /*
+         * Note: preempt is already disabled around the kprobe handler.
+         * However, we still need an smp_read_barrier_depends() corresponding
+         * to smp_wmb() in rcu_assign_pointer() to access the pointer.
+         */
+        struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
+
+        if (unlikely(!file))
+                return;
 
-        /* Note: preempt is already disabled around the kprobe handler */
         while (*file) {
                 __kprobe_trace_func(tp, regs, *file);
                 file++;
@@ -925,9 +945,16 @@ static __kprobes void
 kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
                      struct pt_regs *regs)
 {
-        struct ftrace_event_file **file = tp->files;
+        /*
+         * Note: preempt is already disabled around the kprobe handler.
+         * However, we still need an smp_read_barrier_depends() corresponding
+         * to smp_wmb() in rcu_assign_pointer() to access the pointer.
+         */
+        struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
+
+        if (unlikely(!file))
+                return;
 
-        /* Note: preempt is already disabled around the kprobe handler */
         while (*file) {
                 __kretprobe_trace_func(tp, ri, regs, *file);
                 file++;
@@ -935,7 +962,7 @@ kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
 }
 
 /* Event entry printers */
-enum print_line_t
+static enum print_line_t
 print_kprobe_event(struct trace_iterator *iter, int flags,
                    struct trace_event *event)
 {
@@ -971,7 +998,7 @@ partial:
         return TRACE_TYPE_PARTIAL_LINE;
 }
 
-enum print_line_t
+static enum print_line_t
 print_kretprobe_event(struct trace_iterator *iter, int flags,
                       struct trace_event *event)
 {