trace-cmd: Add debugging to find where leaked records are

Add DEBUG_RECORD macro that records the address of the caller
to get a record, and if there are leaked records existing, print
out where the extra records were allocated from.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 72 insertions, 3 deletions

diff --git a/parse-events.h b/parse-events.h
index 3a4ef08..5c58b62 100644
--- a/parse-events.h
+++ b/parse-events.h
@@ -35,6 +35,10 @@
 #define TRACE_SEQ_BUF_SIZE 4096
 #endif
 
+#ifndef DEBUG_RECORD
+#define DEBUG_RECORD 0
+#endif
+
 struct record {
         unsigned long long      ts;
         unsigned long long      offset;
@@ -46,6 +50,11 @@ struct record {
         int                     ref_count;
         int                     locked;         /* Do not free, even if ref_count is zero */
         void                    *private;
+#if DEBUG_RECORD
+        struct record           *prev;
+        struct record           *next;
+        long                    alloc_addr;
+#endif
 };
 
 /*
diff --git a/trace-input.c b/trace-input.c
index 62e9f3f..377ace7 100644
--- a/trace-input.c
+++ b/trace-input.c
@@ -54,6 +54,9 @@ struct page {
         void                    *map;
         int                     ref_count;
         long long               lost_events;
+#if DEBUG_RECORD
+        struct record           *records;
+#endif
 };
 
 struct cpu_data {
@@ -92,6 +95,53 @@ struct tracecmd_input {
 
 __thread struct tracecmd_input *tracecmd_curr_thread_handle;
 
+#if DEBUG_RECORD
+static void remove_record(struct page *page, struct record *record)
+{
+        if (record->prev)
+                record->prev->next = record->next;
+        else
+                page->records = record->next;
+        if (record->next)
+                record->next->prev = record->prev;
+}
+static void add_record(struct page *page, struct record *record)
+{
+        if (page->records)
+                page->records->prev = record;
+        record->next = page->records;
+        record->prev = NULL;
+        page->records = record;
+}
+static const char *show_records(struct list_head *pages)
+{
+        static char buf[BUFSIZ + 1];
+        struct record *record;
+        struct page *page;
+        int len;
+
+        memset(buf, 0, sizeof(buf));
+        len = 0;
+        list_for_each_entry(page, pages, struct page, list) {
+                for (record = page->records; record; record = record->next) {
+                        int n;
+                        n = snprintf(buf+len, BUFSIZ - len, " 0x%lx", record->alloc_addr);
+                        len += n;
+                        if (len >= BUFSIZ)
+                                break;
+                }
+        }
+        return buf;
+}
+#else
+static inline void remove_record(struct page *page, struct record *record) {}
+static inline void add_record(struct page *page, struct record *record) {}
+static const char *show_records(struct list_head *pages)
+{
+        return "";
+}
+#endif
+
 static int init_cpu(struct tracecmd_input *handle, int cpu);
 
 static int do_read(struct tracecmd_input *handle, void *data, int size)
@@ -648,6 +698,7 @@ static void __free_record(struct record *record)
 {
         if (record->private) {
                 struct page *page = record->private;
+                remove_record(page, record);
                 __free_page(page->handle, page);
         }
 
@@ -678,6 +729,10 @@ void free_record(struct record *record)
 void tracecmd_record_ref(struct record *record)
 {
         record->ref_count++;
+#if DEBUG_RECORD
+        /* Update locating of last reference */
+        record->alloc_addr = (unsigned long)__builtin_return_address(0);
+#endif
 }
 
 static void free_next(struct tracecmd_input *handle, int cpu)
@@ -1583,6 +1638,7 @@ read_again:
 
         record->record_size = handle->cpu_data[cpu].index - index;
         record->private = page;
+        add_record(page, record);
         page->ref_count++;
 
         return record;
@@ -1605,9 +1661,12 @@ tracecmd_read_data(struct tracecmd_input *handle, int cpu)
 
         record = tracecmd_peek_data(handle, cpu);
         handle->cpu_data[cpu].next = NULL;
-        if (record)
+        if (record) {
                 record->locked = 0;
-
+#if DEBUG_RECORD
+                record->alloc_addr = (unsigned long)__builtin_return_address(0);
+#endif
+        }
         return record;
 }
 
@@ -2124,7 +2183,8 @@ void tracecmd_close(struct tracecmd_input *handle)
                 free_next(handle, cpu);
                 free_page(handle, cpu);
                 if (!list_empty(&handle->cpu_data[cpu].pages))
-                        warning("pages still allocated on cpu %d", cpu);
+                        warning("pages still allocated on cpu %d%s",
+                                cpu, show_records(&handle->cpu_data[cpu].pages));
         }
 
         free(handle->cpu_data);