sched_trace: make inclusion optional

We don't always need the file in the kernel.

2 files changed, 10 insertions, 116 deletions

diff --git a/litmus/Makefile b/litmus/Makefile
index 545203876a..3c39899f93 100644
--- a/litmus/Makefile
+++ b/litmus/Makefile
@@ -2,7 +2,7 @@
 # Makefile for LITMUS^RT
 #
 
-obj-y     = sched_plugin.o litmus.o sched_trace.o \
+obj-y     = sched_plugin.o litmus.o \
             edf_common.o jobs.o \
             rt_domain.o fdso.o sync.o \
             fmlp.o srp.o norqlock.o \
@@ -12,3 +12,4 @@ obj-y     = sched_plugin.o litmus.o sched_trace.o \
             sched_pfair.o
 
 obj-$(CONFIG_FEATHER_TRACE) += trace.o ft_event.o
+obj-$(CONFIG_SCHED_DEBUG_TRACE) +=  sched_trace.o
\ No newline at end of file
diff --git a/litmus/sched_trace.c b/litmus/sched_trace.c
index 43447851da..527a58b696 100644
--- a/litmus/sched_trace.c
+++ b/litmus/sched_trace.c
@@ -13,7 +13,6 @@
 #include <litmus/sched_trace.h>
 #include <litmus/litmus.h>
 
-
 typedef struct {
         /*      guard read and write pointers                   */
         spinlock_t      lock;
@@ -246,51 +245,18 @@ typedef struct {
 #define EMPTY_TRACE_BUFFER \
         { .buf = EMPTY_RING_BUFFER, .reader_cnt = ATOMIC_INIT(0)}
 
-static DEFINE_PER_CPU(trace_buffer_t, trace_buffer);
-
-#ifdef CONFIG_SCHED_DEBUG_TRACE
 static spinlock_t               log_buffer_lock = SPIN_LOCK_UNLOCKED;
-#endif
 static trace_buffer_t           log_buffer = EMPTY_TRACE_BUFFER;
 
-static void init_buffers(void)
+static void init_log_buffer(void)
 {
-        int i;
-
-        for (i = 0; i < NR_CPUS; i++) {
-                rb_init(&per_cpu(trace_buffer, i).buf);
-                init_MUTEX(&per_cpu(trace_buffer, i).reader_mutex);
-                atomic_set(&per_cpu(trace_buffer, i).reader_cnt, 0);
-        }
         /* only initialize the mutex, the rest was initialized as part
          * of the static initialization macro
          */
         init_MUTEX(&log_buffer.reader_mutex);
 }
 
-static int trace_release(struct inode *in, struct file *filp)
-{
-        int error               = -EINVAL;
-        trace_buffer_t* buf     = filp->private_data;
-
-        BUG_ON(!filp->private_data);
-
-        if (down_interruptible(&buf->reader_mutex)) {
-                error = -ERESTARTSYS;
-                goto out;
-        }
-
-        /*      last release must deallocate buffers    */
-        if (atomic_dec_return(&buf->reader_cnt) == 0) {
-                error = rb_free_buf(&buf->buf);
-        }
-
-        up(&buf->reader_mutex);
- out:
-        return error;
-}
-
-static ssize_t trace_read(struct file *filp, char __user *to, size_t len,
+static ssize_t log_read(struct file *filp, char __user *to, size_t len,
                       loff_t *f_pos)
 {
         /*      we ignore f_pos, this is strictly sequential */
@@ -333,46 +299,6 @@ static ssize_t trace_read(struct file *filp, char __user *to, size_t len,
 }
 
 
-/* trace_open - Open one of the per-CPU sched_trace buffers.
- */
-static int trace_open(struct inode *in, struct file *filp)
-{
-        int error               = -EINVAL;
-        int cpu                 = MINOR(in->i_rdev);
-        trace_buffer_t* buf;
-
-        if (!cpu_online(cpu)) {
-                printk(KERN_WARNING "sched trace: "
-                        "CPU #%d is not online. (open failed)\n", cpu);
-                error = -ENODEV;
-                goto out;
-        }
-
-        buf = &per_cpu(trace_buffer, cpu);
-
-        if (down_interruptible(&buf->reader_mutex)) {
-                error = -ERESTARTSYS;
-                goto out;
-        }
-
-        /*      first open must allocate buffers        */
-        if (atomic_inc_return(&buf->reader_cnt) == 1) {
-                if ((error = rb_alloc_buf(&buf->buf, BUFFER_ORDER)))
-                {
-                        atomic_dec(&buf->reader_cnt);
-                        goto out_unlock;
-                }
-        }
-
-        error = 0;
-        filp->private_data = buf;
-
- out_unlock:
-        up(&buf->reader_mutex);
- out:
-        return error;
-}
-
 
 extern int trace_override;
 
@@ -401,7 +327,7 @@ static int log_open(struct inode *in, struct file *filp)
 
         error = 0;
         filp->private_data = buf;
-        printk(KERN_DEBUG "sched_trace buf: from 0x%p to 0x%p  length: %lx\n",
+        printk(KERN_DEBUG "sched_trace buf: from 0x%p to 0x%p  length: %x\n",
                buf->buf.buf, buf->buf.end, buf->buf.end - buf->buf.buf);
         trace_override++;
  out_unlock:
@@ -441,19 +367,8 @@ static int log_release(struct inode *in, struct file *filp)
  *
  * This should be converted to dynamic allocation at some point...
  */
-#define TRACE_MAJOR     250
 #define LOG_MAJOR       251
 
-/* trace_fops - The file operations for accessing the per-CPU scheduling event
- *              trace buffers.
- */
-struct file_operations trace_fops = {
-        .owner   = THIS_MODULE,
-        .open    = trace_open,
-        .release = trace_release,
-        .read    = trace_read,
-};
-
 /* log_fops  - The file operations for accessing the global LITMUS log message
  *             buffer.
  *
@@ -463,7 +378,7 @@ struct file_operations log_fops = {
         .owner   = THIS_MODULE,
         .open    = log_open,
         .release = log_release,
-        .read    = trace_read,
+        .read    = log_read,
 };
 
 static int __init register_buffer_dev(const char* name,
@@ -502,34 +417,15 @@ static int __init register_buffer_dev(const char* name,
 
 static int __init init_sched_trace(void)
 {
-        int error1 = 0, error2 = 0;
-
-        printk("Initializing scheduler trace device\n");
-        init_buffers();
+        printk("Initializing TRACE() device\n");
+        init_log_buffer();
 
-        error1 = register_buffer_dev("schedtrace", &trace_fops,
-                                    TRACE_MAJOR, NR_CPUS);
-
-        error2 = register_buffer_dev("litmus_log", &log_fops,
-                                     LOG_MAJOR, 1);
-        if (error1 || error2)
-                return min(error1, error2);
-        else
-                return 0;
+        return register_buffer_dev("litmus_log", &log_fops,
+                                   LOG_MAJOR, 1);
 }
 
 module_init(init_sched_trace);
 
-/******************************************************************************/
-/*                                KERNEL API                                  */
-/******************************************************************************/
-
-/* The per-CPU LITMUS log buffer. Don't put it on the stack, it is too big for
- * that and the kernel gets very picky with nested interrupts and small stacks.
- */
-
-#ifdef CONFIG_SCHED_DEBUG_TRACE
-
 #define MSG_SIZE 255
 static DEFINE_PER_CPU(char[MSG_SIZE], fmt_buffer);
 
@@ -564,6 +460,3 @@ void sched_trace_log_message(const char* fmt, ...)
         local_irq_restore(flags);
         va_end(args);
 }
-
-#endif
-