Merge tag 'trace-3.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing cleanups and bugfixes from Steven Rostedt:
 "One bug fix that goes back to 3.10.  Accessing a non existent buffer
  if "possible cpus" is greater than actual CPUs (including offline
  CPUs).

  Namhyung Kim did some reviews of the patches I sent this merge window
  and found a memory leak and had a few clean ups"

* tag 'trace-3.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix check of ftrace_trace_arrays list_empty() check
  tracing: Fix leak of per cpu max data in instances
  tracing: Cleanup saved_cmdlines_size changes
  ring-buffer: Check if buffer exists before polling

3 files changed, 36 insertions, 20 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index c634868c2921..7c56c3d06943 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -543,7 +543,7 @@ static void rb_wake_up_waiters(struct irq_work *work)
  * as data is added to any of the @buffer's cpu buffers. Otherwise
  * it will wait for data to be added to a specific cpu buffer.
  */
-void ring_buffer_wait(struct ring_buffer *buffer, int cpu)
+int ring_buffer_wait(struct ring_buffer *buffer, int cpu)
 {
         struct ring_buffer_per_cpu *cpu_buffer;
         DEFINE_WAIT(wait);
@@ -557,6 +557,8 @@ void ring_buffer_wait(struct ring_buffer *buffer, int cpu)
         if (cpu == RING_BUFFER_ALL_CPUS)
                 work = &buffer->irq_work;
         else {
+                if (!cpumask_test_cpu(cpu, buffer->cpumask))
+                        return -ENODEV;
                 cpu_buffer = buffer->buffers[cpu];
                 work = &cpu_buffer->irq_work;
         }
@@ -591,6 +593,7 @@ void ring_buffer_wait(struct ring_buffer *buffer, int cpu)
                 schedule();
 
         finish_wait(&work->waiters, &wait);
+        return 0;
 }
 
 /**
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 16f7038d1f4d..384ede311717 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1085,13 +1085,13 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 }
 #endif /* CONFIG_TRACER_MAX_TRACE */
 
-static void wait_on_pipe(struct trace_iterator *iter)
+static int wait_on_pipe(struct trace_iterator *iter)
 {
         /* Iterators are static, they should be filled or empty */
         if (trace_buffer_iter(iter, iter->cpu_file))
-                return;
+                return 0;
 
-        ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file);
+        return ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file);
 }
 
 #ifdef CONFIG_FTRACE_STARTUP_TEST
@@ -1338,7 +1338,7 @@ static int trace_create_savedcmd(void)
 {
         int ret;
 
-        savedcmd = kmalloc(sizeof(struct saved_cmdlines_buffer), GFP_KERNEL);
+        savedcmd = kmalloc(sizeof(*savedcmd), GFP_KERNEL);
         if (!savedcmd)
                 return -ENOMEM;
 
@@ -3840,7 +3840,7 @@ tracing_saved_cmdlines_size_read(struct file *filp, char __user *ubuf,
         int r;
 
         arch_spin_lock(&trace_cmdline_lock);
-        r = sprintf(buf, "%u\n", savedcmd->cmdline_num);
+        r = scnprintf(buf, sizeof(buf), "%u\n", savedcmd->cmdline_num);
         arch_spin_unlock(&trace_cmdline_lock);
 
         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
@@ -3857,7 +3857,7 @@ static int tracing_resize_saved_cmdlines(unsigned int val)
 {
         struct saved_cmdlines_buffer *s, *savedcmd_temp;
 
-        s = kmalloc(sizeof(struct saved_cmdlines_buffer), GFP_KERNEL);
+        s = kmalloc(sizeof(*s), GFP_KERNEL);
         if (!s)
                 return -ENOMEM;
 
@@ -4378,6 +4378,7 @@ tracing_poll_pipe(struct file *filp, poll_table *poll_table)
 static int tracing_wait_pipe(struct file *filp)
 {
         struct trace_iterator *iter = filp->private_data;
+        int ret;
 
         while (trace_empty(iter)) {
 
@@ -4399,10 +4400,13 @@ static int tracing_wait_pipe(struct file *filp)
 
                 mutex_unlock(&iter->mutex);
 
-                wait_on_pipe(iter);
+                ret = wait_on_pipe(iter);
 
                 mutex_lock(&iter->mutex);
 
+                if (ret)
+                        return ret;
+
                 if (signal_pending(current))
                         return -EINTR;
         }
@@ -5327,8 +5331,12 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
                                 goto out_unlock;
                         }
                         mutex_unlock(&trace_types_lock);
-                        wait_on_pipe(iter);
+                        ret = wait_on_pipe(iter);
                         mutex_lock(&trace_types_lock);
+                        if (ret) {
+                                size = ret;
+                                goto out_unlock;
+                        }
                         if (signal_pending(current)) {
                                 size = -EINTR;
                                 goto out_unlock;
@@ -5538,8 +5546,10 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                         goto out;
                 }
                 mutex_unlock(&trace_types_lock);
-                wait_on_pipe(iter);
+                ret = wait_on_pipe(iter);
                 mutex_lock(&trace_types_lock);
+                if (ret)
+                        goto out;
                 if (signal_pending(current)) {
                         ret = -EINTR;
                         goto out;
@@ -6232,22 +6242,25 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
         return 0;
 }
 
+static void free_trace_buffer(struct trace_buffer *buf)
+{
+        if (buf->buffer) {
+                ring_buffer_free(buf->buffer);
+                buf->buffer = NULL;
+                free_percpu(buf->data);
+                buf->data = NULL;
+        }
+}
+
 static void free_trace_buffers(struct trace_array *tr)
 {
         if (!tr)
                 return;
 
-        if (tr->trace_buffer.buffer) {
-                ring_buffer_free(tr->trace_buffer.buffer);
-                tr->trace_buffer.buffer = NULL;
-                free_percpu(tr->trace_buffer.data);
-        }
+        free_trace_buffer(&tr->trace_buffer);
 
 #ifdef CONFIG_TRACER_MAX_TRACE
-        if (tr->max_buffer.buffer) {
-                ring_buffer_free(tr->max_buffer.buffer);
-                tr->max_buffer.buffer = NULL;
-        }
+        free_trace_buffer(&tr->max_buffer);
 #endif
 }
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9e82551dd566..9258f5a815db 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -252,7 +252,7 @@ static inline struct trace_array *top_trace_array(void)
 {
         struct trace_array *tr;
 
-        if (list_empty(ftrace_trace_arrays.prev))
+        if (list_empty(&ftrace_trace_arrays))
                 return NULL;
 
         tr = list_entry(ftrace_trace_arrays.prev,