1 files changed, 14 insertions, 4 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2596b5a968c4..5653c6b07ba1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -518,7 +518,15 @@ int register_tracer(struct tracer *type)
                 return -1;
         }
 
+        /*
+         * When this gets called we hold the BKL which means that
+         * preemption is disabled. Various trace selftests however
+         * need to disable and enable preemption for successful tests.
+         * So we drop the BKL here and grab it after the tests again.
+         */
+        unlock_kernel();
         mutex_lock(&trace_types_lock);
+
         for (t = trace_types; t; t = t->next) {
                 if (strcmp(type->name, t->name) == 0) {
                         /* already found */
@@ -541,9 +549,9 @@ int register_tracer(struct tracer *type)
                  * internal tracing to verify that everything is in order.
                  * If we fail, we do not register this tracer.
                  */
-                for_each_tracing_cpu(i) {
+                for_each_tracing_cpu(i)
                         tracing_reset(tr, i);
-                }
+
                 current_trace = type;
                 /* the test is responsible for initializing and enabling */
                 pr_info("Testing tracer %s: ", type->name);
@@ -555,9 +563,9 @@ int register_tracer(struct tracer *type)
                         goto out;
                 }
                 /* Only reset on passing, to avoid touching corrupted buffers */
-                for_each_tracing_cpu(i) {
+                for_each_tracing_cpu(i)
                         tracing_reset(tr, i);
-                }
+
                 printk(KERN_CONT "PASSED\n");
         }
 #endif
@@ -570,6 +578,7 @@ int register_tracer(struct tracer *type)
 
  out:
         mutex_unlock(&trace_types_lock);
+        lock_kernel();
 
         return ret;
 }
@@ -2178,6 +2187,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
                         ring_buffer_read_finish(iter->buffer_iter[cpu]);
         }
         mutex_unlock(&trace_types_lock);
+        kfree(iter);
 
         return ERR_PTR(-ENOMEM);
 }