Tracing cleanups and simplify tb_set_size(). Dynamic

buffer shrinking is unsafe without heavier weight SMP
synchronisation.

Signed-off-by: Keir Fraser <keir@xensource.com>

1 files changed, 12 insertions, 67 deletions

diff --git a/xen/include/xen/trace.h b/xen/include/xen/trace.h
index 4e2b431eeb..8e5e282769 100644
--- a/xen/include/xen/trace.h
+++ b/xen/include/xen/trace.h
@@ -32,10 +32,7 @@
 #include <public/dom0_ops.h>
 #include <public/trace.h>
 
-extern struct t_buf *t_bufs[];
 extern int tb_init_done;
-extern unsigned long tb_cpu_mask;
-extern u32 tb_event_mask;
 
 /* Used to initialise trace buffer functionality */
 void init_trace_bufs(void);
@@ -43,72 +40,20 @@ void init_trace_bufs(void);
 /* used to retrieve the physical address of the trace buffers */
 int tb_control(dom0_tbufcontrol_t *tbc);
 
-/**
- * trace - Enters a trace tuple into the trace buffer for the current CPU.
- * @event: the event type being logged
- * @d1...d5: the data items for the event being logged
- *
- * Logs a trace record into the appropriate buffer.  Returns nonzero on
- * failure, otherwise 0.  Failure occurs only if the trace buffers are not yet
- * initialised.
- */
-static inline int trace(u32 event, unsigned long d1, unsigned long d2,
-                        unsigned long d3, unsigned long d4, unsigned long d5)
-{
-    atomic_t old, new, seen;
-    struct t_buf *buf;
-    struct t_rec *rec;
-
-    if ( !tb_init_done )
-        return -1;
-
-    if ( (tb_event_mask & event) == 0 )
-        return 0;
-
-    /* match class */
-    if ( ((tb_event_mask >> TRC_CLS_SHIFT) & (event >> TRC_CLS_SHIFT)) == 0 )
-        return 0;
-
-    /* then match subclass */
-    if ( (((tb_event_mask >> TRC_SUBCLS_SHIFT) & 0xf )
-                & ((event >> TRC_SUBCLS_SHIFT) & 0xf )) == 0 )
-        return 0;
-
-    if ( (tb_cpu_mask & (1UL << smp_processor_id())) == 0 )
-        return 0;
-
-    buf = t_bufs[smp_processor_id()];
-
-    do
-    {
-        old = buf->rec_idx;
-        _atomic_set(new, (_atomic_read(old) + 1) % buf->rec_num);
-        seen = atomic_compareandswap(old, new, &buf->rec_idx);
-    }
-    while ( unlikely(_atomic_read(seen) != _atomic_read(old)) );
-
-    wmb();
-
-    rec = &buf->rec[_atomic_read(old)];
-    rdtscll(rec->cycles);
-    rec->event   = event;
-    rec->data[0] = d1;
-    rec->data[1] = d2;
-    rec->data[2] = d3;
-    rec->data[3] = d4;
-    rec->data[4] = d5;
-
-    return 0;
-}
+void trace(u32 event, unsigned long d1, unsigned long d2,
+           unsigned long d3, unsigned long d4, unsigned long d5);
 
 /* Avoids troubling the caller with casting their arguments to a trace macro */
-#define trace_do_casts(e,d1,d2,d3,d4,d5)  \
-                 trace(e,                 \
-                       (unsigned long)d1, \
-                       (unsigned long)d2, \
-                       (unsigned long)d3, \
-                       (unsigned long)d4, \
-                       (unsigned long)d5)
+#define trace_do_casts(e,d1,d2,d3,d4,d5) \
+    do {                                 \
+        if ( tb_init_done )              \
+            trace(e,                     \
+                 (unsigned long)d1,      \
+                 (unsigned long)d2,      \
+                 (unsigned long)d3,      \
+                 (unsigned long)d4,      \
+                 (unsigned long)d5);     \
+    } while ( 0 )
 
 /* Convenience macros for calling the trace function. */
 #define TRACE_0D(event)                trace_do_casts(event,0, 0, 0, 0, 0 )