Make TRACING more robust in the early boot phase.

1 files changed, 25 insertions, 13 deletions

diff --git a/kernel/sched_trace.c b/kernel/sched_trace.c
index fa7bad33a5..dbc99bb026 100644
--- a/kernel/sched_trace.c
+++ b/kernel/sched_trace.c
@@ -35,15 +35,18 @@ typedef struct {
 
 } ring_buffer_t;
 
+#define EMPTY_RING_BUFFER {     \
+        .lock     = SPIN_LOCK_UNLOCKED,         \
+        .del_lock = RW_LOCK_UNLOCKED,           \
+        .buf      = NULL,                       \
+        .end      = NULL,                       \
+        .writep   = NULL,                       \
+        .readp    = NULL                        \
+}
 
 void rb_init(ring_buffer_t* buf) 
 {
-        buf->lock       = SPIN_LOCK_UNLOCKED;
-        buf->del_lock   = RW_LOCK_UNLOCKED;
-        buf->buf        = NULL;
-        buf->end        = NULL;
-        buf->writep     = NULL;
-        buf->readp      = NULL;
+        *buf = (ring_buffer_t) EMPTY_RING_BUFFER;
 }
 
 int rb_alloc_buf(ring_buffer_t* buf, unsigned long order)
@@ -226,6 +229,7 @@ int rb_get(ring_buffer_t* buf, char* mem, size_t len)
 /******************************************************************************/
 
 
+
 /* Allocate a buffer of about 1 MB per CPU.
  *
  */
@@ -237,10 +241,17 @@ typedef struct {
         struct semaphore        reader_mutex;
 } trace_buffer_t;
 
+
+
+/* This does not initialize the semaphore!! */
+
+#define EMPTY_TRACE_BUFFER \
+        { .buf = EMPTY_RING_BUFFER, .reader_cnt = ATOMIC_INIT(0)}
+
 static DEFINE_PER_CPU(trace_buffer_t, trace_buffer);
 
-static queuelock_t              log_buffer_lock;
-static trace_buffer_t           log_buffer;
+static spinlock_t               log_buffer_lock = SPIN_LOCK_UNLOCKED;
+static trace_buffer_t           log_buffer = EMPTY_TRACE_BUFFER;
 
 static void init_buffers(void) 
 {
@@ -251,9 +262,10 @@ static void init_buffers(void)
                 init_MUTEX(&per_cpu(trace_buffer, i).reader_mutex);
                 atomic_set(&per_cpu(trace_buffer, i).reader_cnt, 0);
         }
-        rb_init(&log_buffer.buf);
+        /* only initialize the mutex, the rest was initialized as part 
+         * of the static initialization macro
+         */
         init_MUTEX(&log_buffer.reader_mutex);
-        atomic_set(&log_buffer.reader_cnt, 0);
 }
 
 static int trace_release(struct inode *in, struct file *filp)
@@ -465,7 +477,7 @@ static int __init init_sched_trace(void)
         int error1 = 0, error2 = 0;
 
         printk("Initializing scheduler trace device\n");
-        queue_lock_init(&log_buffer_lock);
+        //queue_lock_init(&log_buffer_lock);
         init_buffers();
 
         error1 = register_buffer_dev("schedtrace", &trace_fops, 
@@ -512,12 +524,12 @@ void sched_trace_log_message(const char* fmt, ...)
         buf = __get_cpu_var(fmt_buffer);
         len = vscnprintf(buf, MSG_SIZE, fmt, args);
 
-        queue_lock(&log_buffer_lock);
+        spin_lock(&log_buffer_lock);
         /* Don't copy the trailing null byte, we don't want null bytes
          * in a text file. 
          */
         rb_put(&log_buffer.buf, buf, len);
-        queue_unlock(&log_buffer_lock);
+        spin_unlock(&log_buffer_lock);
 
         local_irq_restore(flags);
         va_end(args);