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

Pull tracing fixes and cleanups from Steven Rostedt:
 "This contains fixes, optimizations and some clean ups

  Some of the fixes need to go back to 3.10.  They are minor, and deal
  mostly with incorrect ref counting in accessing event files.

  There was a couple of optimizations that should have perf perform a
  bit better when accessing trace events.

  And some various clean ups.  Some of the clean ups are necessary to
  help in a fix to a theoretical race between opening a event file and
  deleting that event"

* tag 'trace-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Kill the unbalanced tr->ref++ in tracing_buffers_open()
  tracing: Kill trace_array->waiter
  tracing: Do not (ab)use trace_seq in event_id_read()
  tracing: Simplify the iteration logic in f_start/f_next
  tracing: Add ref_data to function and fgraph tracer structs
  tracing: Miscellaneous fixes for trace_array ref counting
  tracing: Fix error handling to ensure instances can always be removed
  tracing/kprobe: Wait for disabling all running kprobe handlers
  tracing/perf: Move the PERF_MAX_TRACE_SIZE check into perf_trace_buf_prepare()
  tracing/syscall: Avoid perf_trace_buf_*() if sys_data->perf_events is empty
  tracing/function: Avoid perf_trace_buf_*() if event_function.perf_events is empty
  tracing: Typo fix on ring buffer comments
  tracing: Use trace_seq_puts()/trace_seq_putc() where possible
  tracing: Use correct config guard CONFIG_STACK_TRACER

13 files changed, 166 insertions, 151 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index e444ff88f0a4..cc2f66f68dc5 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -36,11 +36,11 @@ int ring_buffer_print_entry_header(struct trace_seq *s)
 {
         int ret;
 
-        ret = trace_seq_printf(s, "# compressed entry header\n");
-        ret = trace_seq_printf(s, "\ttype_len    :    5 bits\n");
-        ret = trace_seq_printf(s, "\ttime_delta  :   27 bits\n");
-        ret = trace_seq_printf(s, "\tarray       :   32 bits\n");
-        ret = trace_seq_printf(s, "\n");
+        ret = trace_seq_puts(s, "# compressed entry header\n");
+        ret = trace_seq_puts(s, "\ttype_len    :    5 bits\n");
+        ret = trace_seq_puts(s, "\ttime_delta  :   27 bits\n");
+        ret = trace_seq_puts(s, "\tarray       :   32 bits\n");
+        ret = trace_seq_putc(s, '\n');
         ret = trace_seq_printf(s, "\tpadding     : type == %d\n",
                                RINGBUF_TYPE_PADDING);
         ret = trace_seq_printf(s, "\ttime_extend : type == %d\n",
@@ -1066,7 +1066,7 @@ static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer,
 }
 
 /**
- * check_pages - integrity check of buffer pages
+ * rb_check_pages - integrity check of buffer pages
  * @cpu_buffer: CPU buffer with pages to test
  *
  * As a safety measure we check to make sure the data pages have not
@@ -1258,7 +1258,7 @@ static int rb_cpu_notify(struct notifier_block *self,
 #endif
 
 /**
- * ring_buffer_alloc - allocate a new ring_buffer
+ * __ring_buffer_alloc - allocate a new ring_buffer
  * @size: the size in bytes per cpu that is needed.
  * @flags: attributes to set for the ring buffer.
  *
@@ -1607,6 +1607,7 @@ static void update_pages_handler(struct work_struct *work)
  * ring_buffer_resize - resize the ring buffer
  * @buffer: the buffer to resize.
  * @size: the new size.
+ * @cpu_id: the cpu buffer to resize
  *
  * Minimum size is 2 * BUF_PAGE_SIZE.
  *
@@ -3956,11 +3957,11 @@ EXPORT_SYMBOL_GPL(ring_buffer_consume);
  * expected.
  *
  * After a sequence of ring_buffer_read_prepare calls, the user is
- * expected to make at least one call to ring_buffer_prepare_sync.
+ * expected to make at least one call to ring_buffer_read_prepare_sync.
  * Afterwards, ring_buffer_read_start is invoked to get things going
  * for real.
  *
- * This overall must be paired with ring_buffer_finish.
+ * This overall must be paired with ring_buffer_read_finish.
  */
 struct ring_buffer_iter *
 ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu)
@@ -4009,7 +4010,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync);
  * an intervening ring_buffer_read_prepare_sync must have been
  * performed.
  *
- * Must be paired with ring_buffer_finish.
+ * Must be paired with ring_buffer_read_finish.
  */
 void
 ring_buffer_read_start(struct ring_buffer_iter *iter)
@@ -4031,7 +4032,7 @@ ring_buffer_read_start(struct ring_buffer_iter *iter)
 EXPORT_SYMBOL_GPL(ring_buffer_read_start);
 
 /**
- * ring_buffer_finish - finish reading the iterator of the buffer
+ * ring_buffer_read_finish - finish reading the iterator of the buffer
  * @iter: The iterator retrieved by ring_buffer_start
  *
  * This re-enables the recording to the buffer, and frees the
@@ -4346,6 +4347,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu);
 /**
  * ring_buffer_alloc_read_page - allocate a page to read from buffer
  * @buffer: the buffer to allocate for.
+ * @cpu: the cpu buffer to allocate.
  *
  * This function is used in conjunction with ring_buffer_read_page.
  * When reading a full page from the ring buffer, these functions
@@ -4403,7 +4405,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_free_read_page);
  * to swap with a page in the ring buffer.
  *
  * for example:
- *      rpage = ring_buffer_alloc_read_page(buffer);
+ *      rpage = ring_buffer_alloc_read_page(buffer, cpu);
  *      if (!rpage)
  *              return error;
  *      ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0cd500bffd9b..3f2477713aca 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3008,7 +3008,6 @@ static int tracing_release(struct inode *inode, struct file *file)
 
         iter = m->private;
         tr = iter->tr;
-        trace_array_put(tr);
 
         mutex_lock(&trace_types_lock);
 
@@ -3023,6 +3022,9 @@ static int tracing_release(struct inode *inode, struct file *file)
         if (!iter->snapshot)
                 /* reenable tracing if it was previously enabled */
                 tracing_start_tr(tr);
+
+        __trace_array_put(tr);
+
         mutex_unlock(&trace_types_lock);
 
         mutex_destroy(&iter->mutex);
@@ -3447,6 +3449,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 static int tracing_trace_options_open(struct inode *inode, struct file *file)
 {
         struct trace_array *tr = inode->i_private;
+        int ret;
 
         if (tracing_disabled)
                 return -ENODEV;
@@ -3454,7 +3457,11 @@ static int tracing_trace_options_open(struct inode *inode, struct file *file)
         if (trace_array_get(tr) < 0)
                 return -ENODEV;
 
-        return single_open(file, tracing_trace_options_show, inode->i_private);
+        ret = single_open(file, tracing_trace_options_show, inode->i_private);
+        if (ret < 0)
+                trace_array_put(tr);
+
+        return ret;
 }
 
 static const struct file_operations tracing_iter_fops = {
@@ -3537,14 +3544,14 @@ static const char readme_msg[] =
         "\n  snapshot\t\t- Like 'trace' but shows the content of the static snapshot buffer\n"
         "\t\t\t  Read the contents for more information\n"
 #endif
-#ifdef CONFIG_STACKTRACE
+#ifdef CONFIG_STACK_TRACER
         "  stack_trace\t\t- Shows the max stack trace when active\n"
         "  stack_max_size\t- Shows current max stack size that was traced\n"
         "\t\t\t  Write into this file to reset the max size (trigger a new trace)\n"
 #ifdef CONFIG_DYNAMIC_FTRACE
         "  stack_trace_filter\t- Like set_ftrace_filter but limits what stack_trace traces\n"
 #endif
-#endif /* CONFIG_STACKTRACE */
+#endif /* CONFIG_STACK_TRACER */
 ;
 
 static ssize_t
@@ -3958,6 +3965,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
         if (!iter) {
                 ret = -ENOMEM;
+                __trace_array_put(tr);
                 goto out;
         }
 
@@ -4704,21 +4712,24 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file)
                         ret = PTR_ERR(iter);
         } else {
                 /* Writes still need the seq_file to hold the private data */
+                ret = -ENOMEM;
                 m = kzalloc(sizeof(*m), GFP_KERNEL);
                 if (!m)
-                        return -ENOMEM;
+                        goto out;
                 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
                 if (!iter) {
                         kfree(m);
-                        return -ENOMEM;
+                        goto out;
                 }
+                ret = 0;
+
                 iter->tr = tr;
                 iter->trace_buffer = &tc->tr->max_buffer;
                 iter->cpu_file = tc->cpu;
                 m->private = iter;
                 file->private_data = m;
         }
-
+out:
         if (ret < 0)
                 trace_array_put(tr);
 
@@ -4948,8 +4959,6 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
 
         mutex_lock(&trace_types_lock);
 
-        tr->ref++;
-
         info->iter.tr           = tr;
         info->iter.cpu_file     = tc->cpu;
         info->iter.trace        = tr->current_trace;
@@ -5328,9 +5337,10 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 }
 
 static const struct file_operations tracing_stats_fops = {
-        .open           = tracing_open_generic,
+        .open           = tracing_open_generic_tc,
         .read           = tracing_stats_read,
         .llseek         = generic_file_llseek,
+        .release        = tracing_release_generic_tc,
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -5973,8 +5983,10 @@ static int new_instance_create(const char *name)
                 goto out_free_tr;
 
         ret = event_trace_add_tracer(tr->dir, tr);
-        if (ret)
+        if (ret) {
+                debugfs_remove_recursive(tr->dir);
                 goto out_free_tr;
+        }
 
         init_tracer_debugfs(tr, tr->dir);
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 4a4f6e1828b6..e7d643b8a907 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -214,7 +214,6 @@ struct trace_array {
         struct dentry           *event_dir;
         struct list_head        systems;
         struct list_head        events;
-        struct task_struct      *waiter;
         int                     ref;
 };
 
@@ -680,6 +679,15 @@ extern int trace_selftest_startup_sched_switch(struct tracer *trace,
                                                struct trace_array *tr);
 extern int trace_selftest_startup_branch(struct tracer *trace,
                                          struct trace_array *tr);
+/*
+ * Tracer data references selftest functions that only occur
+ * on boot up. These can be __init functions. Thus, when selftests
+ * are enabled, then the tracers need to reference __init functions.
+ */
+#define __tracer_data           __refdata
+#else
+/* Tracers are seldom changed. Optimize when selftests are disabled. */
+#define __tracer_data           __read_mostly
 #endif /* CONFIG_FTRACE_STARTUP_TEST */
 
 extern void *head_page(struct trace_array_cpu *data);
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 84b1e045faba..80c36bcf66e8 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -236,6 +236,10 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
 
         BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
 
+        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
+                        "perf buffer not large enough"))
+                return NULL;
+
         pc = preempt_count();
 
         *rctxp = perf_swevent_get_recursion_context();
@@ -266,6 +270,10 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
         struct pt_regs regs;
         int rctx;
 
+        head = this_cpu_ptr(event_function.perf_events);
+        if (hlist_empty(head))
+                return;
+
 #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
                     sizeof(u64)) - sizeof(u32))
 
@@ -279,8 +287,6 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
 
         entry->ip = ip;
         entry->parent_ip = parent_ip;
-
-        head = this_cpu_ptr(event_function.perf_events);
         perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
                               1, &regs, head, NULL);
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 7d854290bf81..898f868833f2 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -826,59 +826,33 @@ enum {
 static void *f_next(struct seq_file *m, void *v, loff_t *pos)
 {
         struct ftrace_event_call *call = m->private;
-        struct ftrace_event_field *field;
         struct list_head *common_head = &ftrace_common_fields;
         struct list_head *head = trace_get_fields(call);
+        struct list_head *node = v;
 
         (*pos)++;
 
         switch ((unsigned long)v) {
         case FORMAT_HEADER:
-                if (unlikely(list_empty(common_head)))
-                        return NULL;
-
-                field = list_entry(common_head->prev,
-                                   struct ftrace_event_field, link);
-                return field;
+                node = common_head;
+                break;
 
         case FORMAT_FIELD_SEPERATOR:
-                if (unlikely(list_empty(head)))
-                        return NULL;
-
-                field = list_entry(head->prev, struct ftrace_event_field, link);
-                return field;
+                node = head;
+                break;
 
         case FORMAT_PRINTFMT:
                 /* all done */
                 return NULL;
         }
 
-        field = v;
-        if (field->link.prev == common_head)
+        node = node->prev;
+        if (node == common_head)
                 return (void *)FORMAT_FIELD_SEPERATOR;
-        else if (field->link.prev == head)
+        else if (node == head)
                 return (void *)FORMAT_PRINTFMT;
-
-        field = list_entry(field->link.prev, struct ftrace_event_field, link);
-
-        return field;
-}
-
-static void *f_start(struct seq_file *m, loff_t *pos)
-{
-        loff_t l = 0;
-        void *p;
-
-        /* Start by showing the header */
-        if (!*pos)
-                return (void *)FORMAT_HEADER;
-
-        p = (void *)FORMAT_HEADER;
-        do {
-                p = f_next(m, p, &l);
-        } while (p && l < *pos);
-
-        return p;
+        else
+                return node;
 }
 
 static int f_show(struct seq_file *m, void *v)
@@ -904,8 +878,7 @@ static int f_show(struct seq_file *m, void *v)
                 return 0;
         }
 
-        field = v;
-
+        field = list_entry(v, struct ftrace_event_field, link);
         /*
          * Smartly shows the array type(except dynamic array).
          * Normal:
@@ -932,6 +905,17 @@ static int f_show(struct seq_file *m, void *v)
         return 0;
 }
 
+static void *f_start(struct seq_file *m, loff_t *pos)
+{
+        void *p = (void *)FORMAT_HEADER;
+        loff_t l = 0;
+
+        while (l < *pos && p)
+                p = f_next(m, p, &l);
+
+        return p;
+}
+
 static void f_stop(struct seq_file *m, void *p)
 {
 }
@@ -963,23 +947,14 @@ static ssize_t
 event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 {
         struct ftrace_event_call *call = filp->private_data;
-        struct trace_seq *s;
-        int r;
+        char buf[32];
+        int len;
 
         if (*ppos)
                 return 0;
 
-        s = kmalloc(sizeof(*s), GFP_KERNEL);
-        if (!s)
-                return -ENOMEM;
-
-        trace_seq_init(s);
-        trace_seq_printf(s, "%d\n", call->event.type);
-
-        r = simple_read_from_buffer(ubuf, cnt, ppos,
-                                    s->buffer, s->len);
-        kfree(s);
-        return r;
+        len = sprintf(buf, "%d\n", call->event.type);
+        return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
 }
 
 static ssize_t
@@ -1218,6 +1193,7 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 
 static int ftrace_event_avail_open(struct inode *inode, struct file *file);
 static int ftrace_event_set_open(struct inode *inode, struct file *file);
+static int ftrace_event_release(struct inode *inode, struct file *file);
 
 static const struct seq_operations show_event_seq_ops = {
         .start = t_start,
@@ -1245,7 +1221,7 @@ static const struct file_operations ftrace_set_event_fops = {
         .read = seq_read,
         .write = ftrace_event_write,
         .llseek = seq_lseek,
-        .release = seq_release,
+        .release = ftrace_event_release,
 };
 
 static const struct file_operations ftrace_enable_fops = {
@@ -1323,6 +1299,15 @@ ftrace_event_open(struct inode *inode, struct file *file,
         return ret;
 }
 
+static int ftrace_event_release(struct inode *inode, struct file *file)
+{
+        struct trace_array *tr = inode->i_private;
+
+        trace_array_put(tr);
+
+        return seq_release(inode, file);
+}
+
 static int
 ftrace_event_avail_open(struct inode *inode, struct file *file)
 {
@@ -1336,12 +1321,19 @@ ftrace_event_set_open(struct inode *inode, struct file *file)
 {
         const struct seq_operations *seq_ops = &show_set_event_seq_ops;
         struct trace_array *tr = inode->i_private;
+        int ret;
+
+        if (trace_array_get(tr) < 0)
+                return -ENODEV;
 
         if ((file->f_mode & FMODE_WRITE) &&
             (file->f_flags & O_TRUNC))
                 ftrace_clear_events(tr);
 
-        return ftrace_event_open(inode, file, seq_ops);
+        ret = ftrace_event_open(inode, file, seq_ops);
+        if (ret < 0)
+                trace_array_put(tr);
+        return ret;
 }
 
 static struct event_subsystem *
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 0d883dc057d6..0c7b75a8acc8 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -646,7 +646,7 @@ void print_event_filter(struct ftrace_event_call *call, struct trace_seq *s)
         if (filter && filter->filter_string)
                 trace_seq_printf(s, "%s\n", filter->filter_string);
         else
-                trace_seq_printf(s, "none\n");
+                trace_seq_puts(s, "none\n");
         mutex_unlock(&event_mutex);
 }
 
@@ -660,7 +660,7 @@ void print_subsystem_event_filter(struct event_subsystem *system,
         if (filter && filter->filter_string)
                 trace_seq_printf(s, "%s\n", filter->filter_string);
         else
-                trace_seq_printf(s, DEFAULT_SYS_FILTER_MESSAGE "\n");
+                trace_seq_puts(s, DEFAULT_SYS_FILTER_MESSAGE "\n");
         mutex_unlock(&event_mutex);
 }
 
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index b863f93b30f3..38fe1483c508 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -199,7 +199,7 @@ static int func_set_flag(u32 old_flags, u32 bit, int set)
         return 0;
 }
 
-static struct tracer function_trace __read_mostly =
+static struct tracer function_trace __tracer_data =
 {
         .name           = "function",
         .init           = function_trace_init,
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 8388bc99f2ee..b5c09242683d 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -446,7 +446,7 @@ print_graph_proc(struct trace_seq *s, pid_t pid)
 
         /* First spaces to align center */
         for (i = 0; i < spaces / 2; i++) {
-                ret = trace_seq_printf(s, " ");
+                ret = trace_seq_putc(s, ' ');
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
@@ -457,7 +457,7 @@ print_graph_proc(struct trace_seq *s, pid_t pid)
 
         /* Last spaces to align center */
         for (i = 0; i < spaces - (spaces / 2); i++) {
-                ret = trace_seq_printf(s, " ");
+                ret = trace_seq_putc(s, ' ');
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
@@ -503,7 +503,7 @@ verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
  ------------------------------------------
 
  */
-        ret = trace_seq_printf(s,
+        ret = trace_seq_puts(s,
                 " ------------------------------------------\n");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
@@ -516,7 +516,7 @@ verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
         if (ret == TRACE_TYPE_PARTIAL_LINE)
                 return TRACE_TYPE_PARTIAL_LINE;
 
-        ret = trace_seq_printf(s, " => ");
+        ret = trace_seq_puts(s, " => ");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -524,7 +524,7 @@ verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
         if (ret == TRACE_TYPE_PARTIAL_LINE)
                 return TRACE_TYPE_PARTIAL_LINE;
 
-        ret = trace_seq_printf(s,
+        ret = trace_seq_puts(s,
                 "\n ------------------------------------------\n\n");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
@@ -645,7 +645,7 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
                         ret = print_graph_proc(s, pid);
                         if (ret == TRACE_TYPE_PARTIAL_LINE)
                                 return TRACE_TYPE_PARTIAL_LINE;
-                        ret = trace_seq_printf(s, " | ");
+                        ret = trace_seq_puts(s, " | ");
                         if (!ret)
                                 return TRACE_TYPE_PARTIAL_LINE;
                 }
@@ -657,9 +657,9 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
                 return ret;
 
         if (type == TRACE_GRAPH_ENT)
-                ret = trace_seq_printf(s, "==========>");
+                ret = trace_seq_puts(s, "==========>");
         else
-                ret = trace_seq_printf(s, "<==========");
+                ret = trace_seq_puts(s, "<==========");
 
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
@@ -668,7 +668,7 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
         if (ret != TRACE_TYPE_HANDLED)
                 return ret;
 
-        ret = trace_seq_printf(s, "\n");
+        ret = trace_seq_putc(s, '\n');
 
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
@@ -705,13 +705,13 @@ trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
                 len += strlen(nsecs_str);
         }
 
-        ret = trace_seq_printf(s, " us ");
+        ret = trace_seq_puts(s, " us ");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
         /* Print remaining spaces to fit the row's width */
         for (i = len; i < 7; i++) {
-                ret = trace_seq_printf(s, " ");
+                ret = trace_seq_putc(s, ' ');
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
@@ -731,13 +731,13 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s,
         /* No real adata, just filling the column with spaces */
         switch (duration) {
         case DURATION_FILL_FULL:
-                ret = trace_seq_printf(s, "              |  ");
+                ret = trace_seq_puts(s, "              |  ");
                 return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
         case DURATION_FILL_START:
-                ret = trace_seq_printf(s, "  ");
+                ret = trace_seq_puts(s, "  ");
                 return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
         case DURATION_FILL_END:
-                ret = trace_seq_printf(s, " |");
+                ret = trace_seq_puts(s, " |");
                 return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
         }
 
@@ -745,10 +745,10 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s,
         if (flags & TRACE_GRAPH_PRINT_OVERHEAD) {
                 /* Duration exceeded 100 msecs */
                 if (duration > 100000ULL)
-                        ret = trace_seq_printf(s, "! ");
+                        ret = trace_seq_puts(s, "! ");
                 /* Duration exceeded 10 msecs */
                 else if (duration > 10000ULL)
-                        ret = trace_seq_printf(s, "+ ");
+                        ret = trace_seq_puts(s, "+ ");
         }
 
         /*
@@ -757,7 +757,7 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s,
          * to fill out the space.
          */
         if (ret == -1)
-                ret = trace_seq_printf(s, "  ");
+                ret = trace_seq_puts(s, "  ");
 
         /* Catching here any failure happenned above */
         if (!ret)
@@ -767,7 +767,7 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s,
         if (ret != TRACE_TYPE_HANDLED)
                 return ret;
 
-        ret = trace_seq_printf(s, "|  ");
+        ret = trace_seq_puts(s, "|  ");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -817,7 +817,7 @@ print_graph_entry_leaf(struct trace_iterator *iter,
 
         /* Function */
         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
-                ret = trace_seq_printf(s, " ");
+                ret = trace_seq_putc(s, ' ');
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
@@ -858,7 +858,7 @@ print_graph_entry_nested(struct trace_iterator *iter,
 
         /* Function */
         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
-                ret = trace_seq_printf(s, " ");
+                ret = trace_seq_putc(s, ' ');
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
@@ -917,7 +917,7 @@ print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
                 if (ret == TRACE_TYPE_PARTIAL_LINE)
                         return TRACE_TYPE_PARTIAL_LINE;
 
-                ret = trace_seq_printf(s, " | ");
+                ret = trace_seq_puts(s, " | ");
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
@@ -1117,7 +1117,7 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 
         /* Closing brace */
         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
-                ret = trace_seq_printf(s, " ");
+                ret = trace_seq_putc(s, ' ');
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
@@ -1129,7 +1129,7 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
          * belongs to, write out the function name.
          */
         if (func_match) {
-                ret = trace_seq_printf(s, "}\n");
+                ret = trace_seq_puts(s, "}\n");
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         } else {
@@ -1179,13 +1179,13 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
         /* Indentation */
         if (depth > 0)
                 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) {
-                        ret = trace_seq_printf(s, " ");
+                        ret = trace_seq_putc(s, ' ');
                         if (!ret)
                                 return TRACE_TYPE_PARTIAL_LINE;
                 }
 
         /* The comment */
-        ret = trace_seq_printf(s, "/* ");
+        ret = trace_seq_puts(s, "/* ");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -1216,7 +1216,7 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
                 s->len--;
         }
 
-        ret = trace_seq_printf(s, " */\n");
+        ret = trace_seq_puts(s, " */\n");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -1448,7 +1448,7 @@ static struct trace_event graph_trace_ret_event = {
         .funcs          = &graph_functions
 };
 
-static struct tracer graph_trace __read_mostly = {
+static struct tracer graph_trace __tracer_data = {
         .name           = "function_graph",
         .open           = graph_trace_open,
         .pipe_open      = graph_trace_open,
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 7ed6976493c8..3811487e7a7a 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -243,11 +243,11 @@ find_event_file_link(struct trace_probe *tp, struct ftrace_event_file *file)
 static int
 disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
 {
+        struct event_file_link *link = NULL;
+        int wait = 0;
         int ret = 0;
 
         if (file) {
-                struct event_file_link *link;
-
                 link = find_event_file_link(tp, file);
                 if (!link) {
                         ret = -EINVAL;
@@ -255,10 +255,7 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
                 }
 
                 list_del_rcu(&link->list);
-                /* synchronize with kprobe_trace_func/kretprobe_trace_func */
-                synchronize_sched();
-                kfree(link);
-
+                wait = 1;
                 if (!list_empty(&tp->files))
                         goto out;
 
@@ -271,8 +268,22 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
                         disable_kretprobe(&tp->rp);
                 else
                         disable_kprobe(&tp->rp.kp);
+                wait = 1;
         }
  out:
+        if (wait) {
+                /*
+                 * Synchronize with kprobe_trace_func/kretprobe_trace_func
+                 * to ensure disabled (all running handlers are finished).
+                 * This is not only for kfree(), but also the caller,
+                 * trace_remove_event_call() supposes it for releasing
+                 * event_call related objects, which will be accessed in
+                 * the kprobe_trace_func/kretprobe_trace_func.
+                 */
+                synchronize_sched();
+                kfree(link);    /* Ignored if link == NULL */
+        }
+
         return ret;
 }
 
@@ -1087,9 +1098,6 @@ kprobe_perf_func(struct trace_probe *tp, struct pt_regs *regs)
         __size = sizeof(*entry) + tp->size + dsize;
         size = ALIGN(__size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                     "profile buffer not large enough"))
-                return;
 
         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
         if (!entry)
@@ -1120,9 +1128,6 @@ kretprobe_perf_func(struct trace_probe *tp, struct kretprobe_instance *ri,
         __size = sizeof(*entry) + tp->size + dsize;
         size = ALIGN(__size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                     "profile buffer not large enough"))
-                return;
 
         entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
         if (!entry)
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index a5e8f4878bfa..b3dcfb2f0fef 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -90,7 +90,7 @@ static int mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
         if (drv)
                 ret += trace_seq_printf(s, " %s\n", drv->name);
         else
-                ret += trace_seq_printf(s, " \n");
+                ret += trace_seq_puts(s, " \n");
         return ret;
 }
 
@@ -107,7 +107,7 @@ static void mmio_pipe_open(struct trace_iterator *iter)
         struct header_iter *hiter;
         struct trace_seq *s = &iter->seq;
 
-        trace_seq_printf(s, "VERSION 20070824\n");
+        trace_seq_puts(s, "VERSION 20070824\n");
 
         hiter = kzalloc(sizeof(*hiter), GFP_KERNEL);
         if (!hiter)
@@ -209,7 +209,7 @@ static enum print_line_t mmio_print_rw(struct trace_iterator *iter)
                         (rw->value >> 0) & 0xff, rw->pc, 0);
                 break;
         default:
-                ret = trace_seq_printf(s, "rw what?\n");
+                ret = trace_seq_puts(s, "rw what?\n");
                 break;
         }
         if (ret)
@@ -245,7 +245,7 @@ static enum print_line_t mmio_print_map(struct trace_iterator *iter)
                         secs, usec_rem, m->map_id, 0UL, 0);
                 break;
         default:
-                ret = trace_seq_printf(s, "map what?\n");
+                ret = trace_seq_puts(s, "map what?\n");
                 break;
         }
         if (ret)
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index bb922d9ee51b..34e7cbac0c9c 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -78,7 +78,7 @@ enum print_line_t trace_print_printk_msg_only(struct trace_iterator *iter)
 
         trace_assign_type(field, entry);
 
-        ret = trace_seq_printf(s, "%s", field->buf);
+        ret = trace_seq_puts(s, field->buf);
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -558,14 +558,14 @@ seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
                         if (ret)
                                 ret = trace_seq_puts(s, "??");
                         if (ret)
-                                ret = trace_seq_puts(s, "\n");
+                                ret = trace_seq_putc(s, '\n');
                         continue;
                 }
                 if (!ret)
                         break;
                 if (ret)
                         ret = seq_print_user_ip(s, mm, ip, sym_flags);
-                ret = trace_seq_puts(s, "\n");
+                ret = trace_seq_putc(s, '\n');
         }
 
         if (mm)
@@ -579,7 +579,7 @@ seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
         int ret;
 
         if (!ip)
-                return trace_seq_printf(s, "0");
+                return trace_seq_putc(s, '0');
 
         if (sym_flags & TRACE_ITER_SYM_OFFSET)
                 ret = seq_print_sym_offset(s, "%s", ip);
@@ -964,14 +964,14 @@ static enum print_line_t trace_fn_trace(struct trace_iterator *iter, int flags,
                 goto partial;
 
         if ((flags & TRACE_ITER_PRINT_PARENT) && field->parent_ip) {
-                if (!trace_seq_printf(s, " <-"))
+                if (!trace_seq_puts(s, " <-"))
                         goto partial;
                 if (!seq_print_ip_sym(s,
                                       field->parent_ip,
                                       flags))
                         goto partial;
         }
-        if (!trace_seq_printf(s, "\n"))
+        if (!trace_seq_putc(s, '\n'))
                 goto partial;
 
         return TRACE_TYPE_HANDLED;
@@ -1210,7 +1210,7 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter,
 
                 if (!seq_print_ip_sym(s, *p, flags))
                         goto partial;
-                if (!trace_seq_puts(s, "\n"))
+                if (!trace_seq_putc(s, '\n'))
                         goto partial;
         }
 
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 322e16461072..8fd03657bc7d 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -175,7 +175,7 @@ print_syscall_exit(struct trace_iterator *iter, int flags,
         entry = syscall_nr_to_meta(syscall);
 
         if (!entry) {
-                trace_seq_printf(s, "\n");
+                trace_seq_putc(s, '\n');
                 return TRACE_TYPE_HANDLED;
         }
 
@@ -566,15 +566,15 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
         if (!sys_data)
                 return;
 
+        head = this_cpu_ptr(sys_data->enter_event->perf_events);
+        if (hlist_empty(head))
+                return;
+
         /* get the size after alignment with the u32 buffer size field */
         size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
         size = ALIGN(size + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
 
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                      "perf buffer not large enough"))
-                return;
-
         rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
                                 sys_data->enter_event->event.type, regs, &rctx);
         if (!rec)
@@ -583,8 +583,6 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
         rec->nr = syscall_nr;
         syscall_get_arguments(current, regs, 0, sys_data->nb_args,
                                (unsigned long *)&rec->args);
-
-        head = this_cpu_ptr(sys_data->enter_event->perf_events);
         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 }
 
@@ -642,18 +640,14 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
         if (!sys_data)
                 return;
 
+        head = this_cpu_ptr(sys_data->exit_event->perf_events);
+        if (hlist_empty(head))
+                return;
+
         /* We can probably do that at build time */
         size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
         size -= sizeof(u32);
 
-        /*
-         * Impossible, but be paranoid with the future
-         * How to put this check outside runtime?
-         */
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                "exit event has grown above perf buffer size"))
-                return;
-
         rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
                                 sys_data->exit_event->event.type, regs, &rctx);
         if (!rec)
@@ -661,8 +655,6 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 
         rec->nr = syscall_nr;
         rec->ret = syscall_get_return_value(current, regs);
-
-        head = this_cpu_ptr(sys_data->exit_event->perf_events);
         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 }
 
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index d5d0cd368a56..a23d2d71188e 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -818,8 +818,6 @@ static void uprobe_perf_print(struct trace_uprobe *tu,
 
         size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
         size = ALIGN(size + tu->size + sizeof(u32), sizeof(u64)) - sizeof(u32);
-        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
-                return;
 
         preempt_disable();
         head = this_cpu_ptr(call->perf_events);