Add optional dynamic assignment of tracing devices major nr

Setting FT_TASK_TRACE_MAJOR, LOG_MAJOR, FT_TRACE_MAJOR to 0
allows to have them automatically assigned by the kernel

1 files changed, 12 insertions, 5 deletions

diff --git a/litmus/sched_trace.c b/litmus/sched_trace.c
index 4c1ea7eab635..87e725a35eb3 100644
--- a/litmus/sched_trace.c
+++ b/litmus/sched_trace.c
@@ -28,6 +28,8 @@
 /*
  * Major number for the tracing char device.
  * the major numbes are from the unassigned/local use block
+ *
+ * set MAJOR to 0 to have it dynamically assigned
  */
 #define LOG_MAJOR       251
 
@@ -328,14 +330,19 @@ static int __init register_buffer_dev(const char* name,
                                       struct file_operations* fops,
                                       int major, int count)
 {
-        dev_t  trace_dev;
+        dev_t trace_dev;
         struct cdev *cdev;
         int error = 0;
 
-        trace_dev = MKDEV(major, 0);
-        error = register_chrdev_region(trace_dev, count, name);
-        if (error)
-        {
+        if(major) {
+                trace_dev = MKDEV(major, 0);
+                error = register_chrdev_region(trace_dev, count, name);
+        } else {
+                /* dynamically allocate major number */
+                error = alloc_chrdev_region(&trace_dev, 0, count, name);
+                major = MAJOR(trace_dev);
+        }
+        if (error) {
                 printk(KERN_WARNING "sched trace: "
                        "Could not register major/minor number %d\n", major);
                 return error;