Merge tag 'trace-fixes-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git...

Pull tracing fixes from Steven Rostedt:
 "Oleg is working on fixing a very tight race between opening a event
  file and deleting that event at the same time (both must be done as
  root).

  I also found a bug while testing Oleg's patches which has to do with a
  race with kprobes using the function tracer.

  There's also a deadlock fix that was introduced with the previous
  fixes"

* tag 'trace-fixes-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Remove locking trace_types_lock from tracing_reset_all_online_cpus()
  ftrace: Add check for NULL regs if ops has SAVE_REGS set
  tracing: Kill trace_cpu struct/members
  tracing: Change tracing_fops/snapshot_fops to rely on tracing_get_cpu()
  tracing: Change tracing_entries_fops to rely on tracing_get_cpu()
  tracing: Change tracing_stats_fops to rely on tracing_get_cpu()
  tracing: Change tracing_buffers_fops to rely on tracing_get_cpu()
  tracing: Change tracing_pipe_fops() to rely on tracing_get_cpu()
  tracing: Introduce trace_create_cpu_file() and tracing_get_cpu()

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 67708f46baaefbd6bca64a34a213c2cc7fda5074..8ce9eefc5bb4f6aae3ffa520152a51eb033adb1e 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1441,12 +1441,22 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
  * the hashes are freed with call_rcu_sched().
  */
 static int
-ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
+ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
 {
        struct ftrace_hash *filter_hash;
        struct ftrace_hash *notrace_hash;
        int ret;
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+       /*
+        * There's a small race when adding ops that the ftrace handler
+        * that wants regs, may be called without them. We can not
+        * allow that handler to be called if regs is NULL.
+        */
+       if (regs == NULL && (ops->flags & FTRACE_OPS_FL_SAVE_REGS))
+               return 0;
+#endif
+
        filter_hash = rcu_dereference_raw_notrace(ops->filter_hash);
        notrace_hash = rcu_dereference_raw_notrace(ops->notrace_hash);
 
@@ -4218,7 +4228,7 @@ static inline void ftrace_startup_enable(int command) { }
 # define ftrace_shutdown_sysctl()      do { } while (0)
 
 static inline int
-ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
+ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
 {
        return 1;
 }
@@ -4241,7 +4251,7 @@ ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip,
        do_for_each_ftrace_op(op, ftrace_control_list) {
                if (!(op->flags & FTRACE_OPS_FL_STUB) &&
                    !ftrace_function_local_disabled(op) &&
-                   ftrace_ops_test(op, ip))
+                   ftrace_ops_test(op, ip, regs))
                        op->func(ip, parent_ip, op, regs);
        } while_for_each_ftrace_op(op);
        trace_recursion_clear(TRACE_CONTROL_BIT);
@@ -4274,7 +4284,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
         */
        preempt_disable_notrace();
        do_for_each_ftrace_op(op, ftrace_ops_list) {
-               if (ftrace_ops_test(op, ip))
+               if (ftrace_ops_test(op, ip, regs))
                        op->func(ip, parent_ip, op, regs);
        } while_for_each_ftrace_op(op);
        preempt_enable_notrace();

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3f2477713acaa9ea17ed54be7e79a4e0794d4c17..882ec1dd15155233f89c8c7bad0d2a6dbf58c45f 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1224,18 +1224,17 @@ void tracing_reset_current(int cpu)
        tracing_reset(&global_trace.trace_buffer, cpu);
 }
 
+/* Must have trace_types_lock held */
 void tracing_reset_all_online_cpus(void)
 {
        struct trace_array *tr;
 
-       mutex_lock(&trace_types_lock);
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
                tracing_reset_online_cpus(&tr->trace_buffer);
 #ifdef CONFIG_TRACER_MAX_TRACE
                tracing_reset_online_cpus(&tr->max_buffer);
 #endif
        }
-       mutex_unlock(&trace_types_lock);
 }
 
 #define SAVED_CMDLINES 128
@@ -2843,6 +2842,17 @@ static int s_show(struct seq_file *m, void *v)
        return 0;
 }
 
+/*
+ * Should be used after trace_array_get(), trace_types_lock
+ * ensures that i_cdev was already initialized.
+ */
+static inline int tracing_get_cpu(struct inode *inode)
+{
+       if (inode->i_cdev) /* See trace_create_cpu_file() */
+               return (long)inode->i_cdev - 1;
+       return RING_BUFFER_ALL_CPUS;
+}
+
 static const struct seq_operations tracer_seq_ops = {
        .start          = s_start,
        .next           = s_next,
@@ -2851,9 +2861,9 @@ static const struct seq_operations tracer_seq_ops = {
 };
 
 static struct trace_iterator *
-__tracing_open(struct trace_array *tr, struct trace_cpu *tc,
-              struct inode *inode, struct file *file, bool snapshot)
+__tracing_open(struct inode *inode, struct file *file, bool snapshot)
 {
+       struct trace_array *tr = inode->i_private;
        struct trace_iterator *iter;
        int cpu;
 
@@ -2894,8 +2904,8 @@ __tracing_open(struct trace_array *tr, struct trace_cpu *tc,
                iter->trace_buffer = &tr->trace_buffer;
        iter->snapshot = snapshot;
        iter->pos = -1;
+       iter->cpu_file = tracing_get_cpu(inode);
        mutex_init(&iter->mutex);
-       iter->cpu_file = tc->cpu;
 
        /* Notify the tracer early; before we stop tracing. */
        if (iter->trace && iter->trace->open)
@@ -2971,44 +2981,22 @@ static int tracing_open_generic_tr(struct inode *inode, struct file *filp)
        filp->private_data = inode->i_private;
 
        return 0;
-       
-}
-
-static int tracing_open_generic_tc(struct inode *inode, struct file *filp)
-{
-       struct trace_cpu *tc = inode->i_private;
-       struct trace_array *tr = tc->tr;
-
-       if (tracing_disabled)
-               return -ENODEV;
-
-       if (trace_array_get(tr) < 0)
-               return -ENODEV;
-
-       filp->private_data = inode->i_private;
-
-       return 0;
-       
 }
 
 static int tracing_release(struct inode *inode, struct file *file)
 {
+       struct trace_array *tr = inode->i_private;
        struct seq_file *m = file->private_data;
        struct trace_iterator *iter;
-       struct trace_array *tr;
        int cpu;
 
-       /* Writes do not use seq_file, need to grab tr from inode */
        if (!(file->f_mode & FMODE_READ)) {
-               struct trace_cpu *tc = inode->i_private;
-
-               trace_array_put(tc->tr);
+               trace_array_put(tr);
                return 0;
        }
 
+       /* Writes do not use seq_file */
        iter = m->private;
-       tr = iter->tr;
-
        mutex_lock(&trace_types_lock);
 
        for_each_tracing_cpu(cpu) {
@@ -3044,15 +3032,6 @@ static int tracing_release_generic_tr(struct inode *inode, struct file *file)
        return 0;
 }
 
-static int tracing_release_generic_tc(struct inode *inode, struct file *file)
-{
-       struct trace_cpu *tc = inode->i_private;
-       struct trace_array *tr = tc->tr;
-
-       trace_array_put(tr);
-       return 0;
-}
-
 static int tracing_single_release_tr(struct inode *inode, struct file *file)
 {
        struct trace_array *tr = inode->i_private;
@@ -3064,8 +3043,7 @@ static int tracing_single_release_tr(struct inode *inode, struct file *file)
 
 static int tracing_open(struct inode *inode, struct file *file)
 {
-       struct trace_cpu *tc = inode->i_private;
-       struct trace_array *tr = tc->tr;
+       struct trace_array *tr = inode->i_private;
        struct trace_iterator *iter;
        int ret = 0;
 
@@ -3073,16 +3051,17 @@ static int tracing_open(struct inode *inode, struct file *file)
                return -ENODEV;
 
        /* If this file was open for write, then erase contents */
-       if ((file->f_mode & FMODE_WRITE) &&
-           (file->f_flags & O_TRUNC)) {
-               if (tc->cpu == RING_BUFFER_ALL_CPUS)
+       if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
+               int cpu = tracing_get_cpu(inode);
+
+               if (cpu == RING_BUFFER_ALL_CPUS)
                        tracing_reset_online_cpus(&tr->trace_buffer);
                else
-                       tracing_reset(&tr->trace_buffer, tc->cpu);
+                       tracing_reset(&tr->trace_buffer, cpu);
        }
 
        if (file->f_mode & FMODE_READ) {
-               iter = __tracing_open(tr, tc, inode, file, false);
+               iter = __tracing_open(inode, file, false);
                if (IS_ERR(iter))
                        ret = PTR_ERR(iter);
                else if (trace_flags & TRACE_ITER_LATENCY_FMT)
@@ -3948,8 +3927,7 @@ tracing_max_lat_write(struct file *filp, const char __user *ubuf,
 
 static int tracing_open_pipe(struct inode *inode, struct file *filp)
 {
-       struct trace_cpu *tc = inode->i_private;
-       struct trace_array *tr = tc->tr;
+       struct trace_array *tr = inode->i_private;
        struct trace_iterator *iter;
        int ret = 0;
 
@@ -3995,9 +3973,9 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
        if (trace_clocks[tr->clock_id].in_ns)
                iter->iter_flags |= TRACE_FILE_TIME_IN_NS;
 
-       iter->cpu_file = tc->cpu;
-       iter->tr = tc->tr;
-       iter->trace_buffer = &tc->tr->trace_buffer;
+       iter->tr = tr;
+       iter->trace_buffer = &tr->trace_buffer;
+       iter->cpu_file = tracing_get_cpu(inode);
        mutex_init(&iter->mutex);
        filp->private_data = iter;
 
@@ -4020,8 +3998,7 @@ fail:
 static int tracing_release_pipe(struct inode *inode, struct file *file)
 {
        struct trace_iterator *iter = file->private_data;
-       struct trace_cpu *tc = inode->i_private;
-       struct trace_array *tr = tc->tr;
+       struct trace_array *tr = inode->i_private;
 
        mutex_lock(&trace_types_lock);
 
@@ -4374,15 +4351,16 @@ static ssize_t
 tracing_entries_read(struct file *filp, char __user *ubuf,
                     size_t cnt, loff_t *ppos)
 {
-       struct trace_cpu *tc = filp->private_data;
-       struct trace_array *tr = tc->tr;
+       struct inode *inode = file_inode(filp);
+       struct trace_array *tr = inode->i_private;
+       int cpu = tracing_get_cpu(inode);
        char buf[64];
        int r = 0;
        ssize_t ret;
 
        mutex_lock(&trace_types_lock);
 
-       if (tc->cpu == RING_BUFFER_ALL_CPUS) {
+       if (cpu == RING_BUFFER_ALL_CPUS) {
                int cpu, buf_size_same;
                unsigned long size;
 
@@ -4409,7 +4387,7 @@ tracing_entries_read(struct file *filp, char __user *ubuf,
                } else
                        r = sprintf(buf, "X\n");
        } else
-               r = sprintf(buf, "%lu\n", per_cpu_ptr(tr->trace_buffer.data, tc->cpu)->entries >> 10);
+               r = sprintf(buf, "%lu\n", per_cpu_ptr(tr->trace_buffer.data, cpu)->entries >> 10);
 
        mutex_unlock(&trace_types_lock);
 
@@ -4421,7 +4399,8 @@ static ssize_t
 tracing_entries_write(struct file *filp, const char __user *ubuf,
                      size_t cnt, loff_t *ppos)
 {
-       struct trace_cpu *tc = filp->private_data;
+       struct inode *inode = file_inode(filp);
+       struct trace_array *tr = inode->i_private;
        unsigned long val;
        int ret;
 
@@ -4435,8 +4414,7 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
 
        /* value is in KB */
        val <<= 10;
-
-       ret = tracing_resize_ring_buffer(tc->tr, val, tc->cpu);
+       ret = tracing_resize_ring_buffer(tr, val, tracing_get_cpu(inode));
        if (ret < 0)
                return ret;
 
@@ -4697,8 +4675,7 @@ struct ftrace_buffer_info {
 #ifdef CONFIG_TRACER_SNAPSHOT
 static int tracing_snapshot_open(struct inode *inode, struct file *file)
 {
-       struct trace_cpu *tc = inode->i_private;
-       struct trace_array *tr = tc->tr;
+       struct trace_array *tr = inode->i_private;
        struct trace_iterator *iter;
        struct seq_file *m;
        int ret = 0;
@@ -4707,7 +4684,7 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file)
                return -ENODEV;
 
        if (file->f_mode & FMODE_READ) {
-               iter = __tracing_open(tr, tc, inode, file, true);
+               iter = __tracing_open(inode, file, true);
                if (IS_ERR(iter))
                        ret = PTR_ERR(iter);
        } else {
@@ -4724,8 +4701,8 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file)
                ret = 0;
 
                iter->tr = tr;
-               iter->trace_buffer = &tc->tr->max_buffer;
-               iter->cpu_file = tc->cpu;
+               iter->trace_buffer = &tr->max_buffer;
+               iter->cpu_file = tracing_get_cpu(inode);
                m->private = iter;
                file->private_data = m;
        }
@@ -4884,11 +4861,11 @@ static const struct file_operations tracing_pipe_fops = {
 };
 
 static const struct file_operations tracing_entries_fops = {
-       .open           = tracing_open_generic_tc,
+       .open           = tracing_open_generic_tr,
        .read           = tracing_entries_read,
        .write          = tracing_entries_write,
        .llseek         = generic_file_llseek,
-       .release        = tracing_release_generic_tc,
+       .release        = tracing_release_generic_tr,
 };
 
 static const struct file_operations tracing_total_entries_fops = {
@@ -4940,8 +4917,7 @@ static const struct file_operations snapshot_raw_fops = {
 
 static int tracing_buffers_open(struct inode *inode, struct file *filp)
 {
-       struct trace_cpu *tc = inode->i_private;
-       struct trace_array *tr = tc->tr;
+       struct trace_array *tr = inode->i_private;
        struct ftrace_buffer_info *info;
        int ret;
 
@@ -4960,7 +4936,7 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
        mutex_lock(&trace_types_lock);
 
        info->iter.tr           = tr;
-       info->iter.cpu_file     = tc->cpu;
+       info->iter.cpu_file     = tracing_get_cpu(inode);
        info->iter.trace        = tr->current_trace;
        info->iter.trace_buffer = &tr->trace_buffer;
        info->spare             = NULL;
@@ -5277,14 +5253,14 @@ static ssize_t
 tracing_stats_read(struct file *filp, char __user *ubuf,
                   size_t count, loff_t *ppos)
 {
-       struct trace_cpu *tc = filp->private_data;
-       struct trace_array *tr = tc->tr;
+       struct inode *inode = file_inode(filp);
+       struct trace_array *tr = inode->i_private;
        struct trace_buffer *trace_buf = &tr->trace_buffer;
+       int cpu = tracing_get_cpu(inode);
        struct trace_seq *s;
        unsigned long cnt;
        unsigned long long t;
        unsigned long usec_rem;
-       int cpu = tc->cpu;
 
        s = kmalloc(sizeof(*s), GFP_KERNEL);
        if (!s)
@@ -5337,10 +5313,10 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 }
 
 static const struct file_operations tracing_stats_fops = {
-       .open           = tracing_open_generic_tc,
+       .open           = tracing_open_generic_tr,
        .read           = tracing_stats_read,
        .llseek         = generic_file_llseek,
-       .release        = tracing_release_generic_tc,
+       .release        = tracing_release_generic_tr,
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -5529,10 +5505,20 @@ static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu)
        return tr->percpu_dir;
 }
 
+static struct dentry *
+trace_create_cpu_file(const char *name, umode_t mode, struct dentry *parent,
+                     void *data, long cpu, const struct file_operations *fops)
+{
+       struct dentry *ret = trace_create_file(name, mode, parent, data, fops);
+
+       if (ret) /* See tracing_get_cpu() */
+               ret->d_inode->i_cdev = (void *)(cpu + 1);
+       return ret;
+}
+
 static void
 tracing_init_debugfs_percpu(struct trace_array *tr, long cpu)
 {
-       struct trace_array_cpu *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
        struct dentry *d_percpu = tracing_dentry_percpu(tr, cpu);
        struct dentry *d_cpu;
        char cpu_dir[30]; /* 30 characters should be more than enough */
@@ -5548,28 +5534,28 @@ tracing_init_debugfs_percpu(struct trace_array *tr, long cpu)
        }
 
        /* per cpu trace_pipe */
-       trace_create_file("trace_pipe", 0444, d_cpu,
-                       (void *)&data->trace_cpu, &tracing_pipe_fops);
+       trace_create_cpu_file("trace_pipe", 0444, d_cpu,
+                               tr, cpu, &tracing_pipe_fops);
 
        /* per cpu trace */
-       trace_create_file("trace", 0644, d_cpu,
-                       (void *)&data->trace_cpu, &tracing_fops);
+       trace_create_cpu_file("trace", 0644, d_cpu,
+                               tr, cpu, &tracing_fops);
 
-       trace_create_file("trace_pipe_raw", 0444, d_cpu,
-                       (void *)&data->trace_cpu, &tracing_buffers_fops);
+       trace_create_cpu_file("trace_pipe_raw", 0444, d_cpu,
+                               tr, cpu, &tracing_buffers_fops);
 
-       trace_create_file("stats", 0444, d_cpu,
-                       (void *)&data->trace_cpu, &tracing_stats_fops);
+       trace_create_cpu_file("stats", 0444, d_cpu,
+                               tr, cpu, &tracing_stats_fops);
 
-       trace_create_file("buffer_size_kb", 0444, d_cpu,
-                       (void *)&data->trace_cpu, &tracing_entries_fops);
+       trace_create_cpu_file("buffer_size_kb", 0444, d_cpu,
+                               tr, cpu, &tracing_entries_fops);
 
 #ifdef CONFIG_TRACER_SNAPSHOT
-       trace_create_file("snapshot", 0644, d_cpu,
-                         (void *)&data->trace_cpu, &snapshot_fops);
+       trace_create_cpu_file("snapshot", 0644, d_cpu,
+                               tr, cpu, &snapshot_fops);
 
-       trace_create_file("snapshot_raw", 0444, d_cpu,
-                       (void *)&data->trace_cpu, &snapshot_raw_fops);
+       trace_create_cpu_file("snapshot_raw", 0444, d_cpu,
+                               tr, cpu, &snapshot_raw_fops);
 #endif
 }
 
@@ -5878,17 +5864,6 @@ struct dentry *trace_instance_dir;
 static void
 init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer);
 
-static void init_trace_buffers(struct trace_array *tr, struct trace_buffer *buf)
-{
-       int cpu;
-
-       for_each_tracing_cpu(cpu) {
-               memset(per_cpu_ptr(buf->data, cpu), 0, sizeof(struct trace_array_cpu));
-               per_cpu_ptr(buf->data, cpu)->trace_cpu.cpu = cpu;
-               per_cpu_ptr(buf->data, cpu)->trace_cpu.tr = tr;
-       }
-}
-
 static int
 allocate_trace_buffer(struct trace_array *tr, struct trace_buffer *buf, int size)
 {
@@ -5906,8 +5881,6 @@ allocate_trace_buffer(struct trace_array *tr, struct trace_buffer *buf, int size
                return -ENOMEM;
        }
 
-       init_trace_buffers(tr, buf);
-
        /* Allocate the first page for all buffers */
        set_buffer_entries(&tr->trace_buffer,
                           ring_buffer_size(tr->trace_buffer.buffer, 0));
@@ -5974,10 +5947,6 @@ static int new_instance_create(const char *name)
        if (allocate_trace_buffers(tr, trace_buf_size) < 0)
                goto out_free_tr;
 
-       /* Holder for file callbacks */
-       tr->trace_cpu.cpu = RING_BUFFER_ALL_CPUS;
-       tr->trace_cpu.tr = tr;
-
        tr->dir = debugfs_create_dir(name, trace_instance_dir);
        if (!tr->dir)
                goto out_free_tr;
@@ -6132,13 +6101,13 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer)
                          tr, &tracing_iter_fops);
 
        trace_create_file("trace", 0644, d_tracer,
-                       (void *)&tr->trace_cpu, &tracing_fops);
+                         tr, &tracing_fops);
 
        trace_create_file("trace_pipe", 0444, d_tracer,
-                       (void *)&tr->trace_cpu, &tracing_pipe_fops);
+                         tr, &tracing_pipe_fops);
 
        trace_create_file("buffer_size_kb", 0644, d_tracer,
-                       (void *)&tr->trace_cpu, &tracing_entries_fops);
+                         tr, &tracing_entries_fops);
 
        trace_create_file("buffer_total_size_kb", 0444, d_tracer,
                          tr, &tracing_total_entries_fops);
@@ -6153,11 +6122,11 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer)
                          &trace_clock_fops);
 
        trace_create_file("tracing_on", 0644, d_tracer,
-                           tr, &rb_simple_fops);
+                         tr, &rb_simple_fops);
 
 #ifdef CONFIG_TRACER_SNAPSHOT
        trace_create_file("snapshot", 0644, d_tracer,
-                         (void *)&tr->trace_cpu, &snapshot_fops);
+                         tr, &snapshot_fops);
 #endif
 
        for_each_tracing_cpu(cpu)
@@ -6451,10 +6420,6 @@ __init static int tracer_alloc_buffers(void)
 
        global_trace.flags = TRACE_ARRAY_FL_GLOBAL;
 
-       /* Holder for file callbacks */
-       global_trace.trace_cpu.cpu = RING_BUFFER_ALL_CPUS;
-       global_trace.trace_cpu.tr = &global_trace;
-
        INIT_LIST_HEAD(&global_trace.systems);
        INIT_LIST_HEAD(&global_trace.events);
        list_add(&global_trace.list, &ftrace_trace_arrays);

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index e7d643b8a907d6dbd027c723115b3d5a21dc9c9e..afaae41b0a0269012ae394dc5df877cd5cf86045 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -130,19 +130,12 @@ enum trace_flag_type {
 
 struct trace_array;
 
-struct trace_cpu {
-       struct trace_array      *tr;
-       struct dentry           *dir;
-       int                     cpu;
-};
-
 /*
  * The CPU trace array - it consists of thousands of trace entries
  * plus some other descriptor data: (for example which task started
  * the trace, etc.)
  */
 struct trace_array_cpu {
-       struct trace_cpu        trace_cpu;
        atomic_t                disabled;
        void                    *buffer_page;   /* ring buffer spare */
 
@@ -196,7 +189,6 @@ struct trace_array {
        bool                    allocated_snapshot;
 #endif
        int                     buffer_disabled;
-       struct trace_cpu        trace_cpu;      /* place holder */
 #ifdef CONFIG_FTRACE_SYSCALLS
        int                     sys_refcount_enter;
        int                     sys_refcount_exit;