Feather-Trace: register devices with sysfs

This patch implements support for Feather-Trace devices to use the sysfs
file system and, consequently, udev support.

This allows us to allocate major/minor numbers for Feather-Trace
devices dynamically, which is desirable because our old static
allocations tend to create conflicts on modern distributions and/or
when there are many cores.

1 files changed, 2 insertions, 5 deletions

diff --git a/litmus/trace.c b/litmus/trace.c
index b3a6b47aad6e..da650dfe7f4d 100644
--- a/litmus/trace.c
+++ b/litmus/trace.c
@@ -71,9 +71,6 @@ feather_callback void save_timestamp_cpu(unsigned long event,
  */
 #define NO_TIMESTAMPS (2 << 11)
 
-/* set MAJOR to 0 to have it dynamically assigned */
-#define FT_TRACE_MAJOR  252
-
 static int alloc_timestamp_buffer(struct ftdev* ftdev, unsigned int idx)
 {
         unsigned int count = NO_TIMESTAMPS;
@@ -94,11 +91,11 @@ static void free_timestamp_buffer(struct ftdev* ftdev, unsigned int idx)
 static int __init init_ft_overhead_trace(void)
 {
         printk("Initializing Feather-Trace overhead tracing device.\n");
-        ftdev_init(&overhead_dev, THIS_MODULE);
+        ftdev_init(&overhead_dev, THIS_MODULE, "ft_trace");
         overhead_dev.minor_cnt = 1; /* only one buffer */
         overhead_dev.alloc = alloc_timestamp_buffer;
         overhead_dev.free  = free_timestamp_buffer;
-        return register_ftdev(&overhead_dev, "ft_trace", FT_TRACE_MAJOR);
+        return register_ftdev(&overhead_dev);
 }
 
 module_init(init_ft_overhead_trace);