trace: Clean up the "try to update atomic until it worked" loops

[qemu.git] / trace / simple.c

diff --git a/trace/simple.c b/trace/simple.c
index 8e175ece735ba26e52c26bdd6227bbbf455baf7c..74701e3272eca6972ae695d1d7dea038a253c689 100644 (file)
--- a/trace/simple.c
+++ b/trace/simple.c
@@ -16,7 +16,7 @@
 #include <signal.h>
 #include <pthread.h>
 #endif
-#include "qemu-timer.h"
+#include "qemu/timer.h"
 #include "trace.h"
 #include "trace/control.h"
 
@@ -53,9 +53,9 @@ enum {
 uint8_t trace_buf[TRACE_BUF_LEN];
 static unsigned int trace_idx;
 static unsigned int writeout_idx;
-static uint64_t dropped_events;
+static int dropped_events;
 static FILE *trace_fp;
-static char *trace_file_name = NULL;
+static char *trace_file_name;
 
 /* * Trace buffer entry */
 typedef struct {
@@ -63,7 +63,7 @@ typedef struct {
     uint64_t timestamp_ns;
     uint32_t length;   /*    in bytes */
     uint32_t reserved; /*    unused */
-    uint8_t arguments[];
+    uint64_t arguments[];
 } TraceRecord;
 
 typedef struct {
@@ -160,25 +160,22 @@ static gpointer writeout_thread(gpointer opaque)
         uint8_t bytes[sizeof(TraceRecord) + sizeof(uint64_t)];
     } dropped;
     unsigned int idx = 0;
-    uint64_t dropped_count;
+    int dropped_count;
     size_t unused __attribute__ ((unused));
 
     for (;;) {
         wait_for_trace_records_available();
 
-        if (dropped_events) {
+        if (g_atomic_int_get(&dropped_events)) {
             dropped.rec.event = DROPPED_EVENT_ID,
             dropped.rec.timestamp_ns = get_clock();
-            dropped.rec.length = sizeof(TraceRecord) + sizeof(dropped_events),
+            dropped.rec.length = sizeof(TraceRecord) + sizeof(uint64_t),
             dropped.rec.reserved = 0;
-            while (1) {
-                dropped_count = dropped_events;
-                if (g_atomic_int_compare_and_exchange((gint *)&dropped_events,
-                                                      dropped_count, 0)) {
-                    break;
-                }
-            }
-            memcpy(dropped.rec.arguments, &dropped_count, sizeof(uint64_t));
+            do {
+                dropped_count = g_atomic_int_get(&dropped_events);
+            } while (!g_atomic_int_compare_and_exchange(&dropped_events,
+                                                        dropped_count, 0));
+            dropped.rec.arguments[0] = dropped_count;
             unused = fwrite(&dropped.rec, dropped.rec.length, 1, trace_fp);
         }
 
@@ -213,22 +210,17 @@ int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasi
     uint32_t rec_len = sizeof(TraceRecord) + datasize;
     uint64_t timestamp_ns = get_clock();
 
-    while (1) {
-        old_idx = trace_idx;
+    do {
+        old_idx = g_atomic_int_get(&trace_idx);
         smp_rmb();
         new_idx = old_idx + rec_len;
 
         if (new_idx - writeout_idx > TRACE_BUF_LEN) {
             /* Trace Buffer Full, Event dropped ! */
-            g_atomic_int_inc((gint *)&dropped_events);
+            g_atomic_int_inc(&dropped_events);
             return -ENOSPC;
         }
-
-        if (g_atomic_int_compare_and_exchange((gint *)&trace_idx,
-                                              old_idx, new_idx)) {
-            break;
-        }
-    }
+    } while (!g_atomic_int_compare_and_exchange(&trace_idx, old_idx, new_idx));
 
     idx = old_idx % TRACE_BUF_LEN;
 
@@ -275,7 +267,8 @@ void trace_record_finish(TraceBufferRecord *rec)
     record.event |= TRACE_RECORD_VALID;
     write_to_buffer(rec->tbuf_idx, &record, sizeof(TraceRecord));
 
-    if ((trace_idx - writeout_idx) > TRACE_BUF_FLUSH_THRESHOLD) {
+    if ((g_atomic_int_get(&trace_idx) - writeout_idx)
+        > TRACE_BUF_FLUSH_THRESHOLD) {
         flush_trace_file(false);
     }
 }
@@ -329,18 +322,12 @@ bool st_set_trace_file(const char *file)
 {
     st_set_trace_file_enabled(false);
 
-    free(trace_file_name);
+    g_free(trace_file_name);
 
     if (!file) {
-        if (asprintf(&trace_file_name, CONFIG_TRACE_FILE, getpid()) < 0) {
-            trace_file_name = NULL;
-            return false;
-        }
+        trace_file_name = g_strdup_printf(CONFIG_TRACE_FILE, getpid());
     } else {
-        if (asprintf(&trace_file_name, "%s", file) < 0) {
-            trace_file_name = NULL;
-            return false;
-        }
+        trace_file_name = g_strdup_printf("%s", file);
     }
 
     st_set_trace_file_enabled(true);