1 files changed, 31 insertions, 7 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b9126ef46a9e..32f9106d612c 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2307,11 +2307,15 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
         if (!iter)
                 return -ENOMEM;
 
+        mutex_lock(&trace_types_lock);
         iter->tr = &global_trace;
         iter->trace = current_trace;
-
         filp->private_data = iter;
 
+        if (iter->trace->pipe_open)
+                iter->trace->pipe_open(iter);
+        mutex_unlock(&trace_types_lock);
+
         return 0;
 }
 
@@ -2380,13 +2384,24 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
                 return cnt;
         }
 
+        mutex_lock(&trace_types_lock);
+        if (iter->trace->read) {
+                ret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
+                if (ret) {
+                        read = ret;
+                        goto out;
+                }
+        }
+
         trace_seq_reset(&iter->seq);
         start = 0;
 
         while (trace_empty(iter)) {
 
-                if ((filp->f_flags & O_NONBLOCK))
-                        return -EAGAIN;
+                if ((filp->f_flags & O_NONBLOCK)) {
+                        read = -EAGAIN;
+                        goto out;
+                }
 
                 /*
                  * This is a make-shift waitqueue. The reason we don't use
@@ -2400,16 +2415,22 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
                 set_current_state(TASK_INTERRUPTIBLE);
                 iter->tr->waiter = current;
 
+                mutex_unlock(&trace_types_lock);
+
                 /* sleep for one second, and try again. */
                 schedule_timeout(HZ);
 
+                mutex_lock(&trace_types_lock);
+
                 iter->tr->waiter = NULL;
 
-                if (signal_pending(current))
-                        return -EINTR;
+                if (signal_pending(current)) {
+                        read = -EINTR;
+                        goto out;
+                }
 
                 if (iter->trace != current_trace)
-                        return 0;
+                        goto out;
 
                 /*
                  * We block until we read something and tracing is disabled.
@@ -2428,7 +2449,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
 
         /* stop when tracing is finished */
         if (trace_empty(iter))
-                return 0;
+                goto out;
 
         if (cnt >= PAGE_SIZE)
                 cnt = PAGE_SIZE - 1;
@@ -2518,6 +2539,9 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
         if (ret)
                 read = -EFAULT;
 
+out:
+        mutex_unlock(&trace_types_lock);
+
         return read;
 }