Please take a look the updated patch. It addresses the issue of using
dlclose before dump, and potential races (between a thread closing a
library and the dumper call).
David
On Sun, Jul 20, 2014 at 11:12 PM, Nathan Sidwell <nat...@acm.org> wrote:
> On 07/20/14 21:38, Xinliang David Li wrote:
>>
>> The gcov_info chain is not duplicated -- there is already one chain
>> (linking only modules of the library) per shared library in current
>> implementation. My change does not affect underlying behavior at all
>> -- it merely introduces a new interface to access private dumper
>> methods associated with shared libs.
>
>
> ah, got it. thanks for clarifying. Can't help thinking gcov_init should be
> doing this, and wondering about dlload/dlclose. Let me think
>
> nathan
Index: libgcc/libgcov.h
===================================================================
--- libgcc/libgcov.h (revision 212682)
+++ libgcc/libgcov.h (working copy)
@@ -218,8 +218,14 @@ extern void __gcov_flush (void) ATTRIBUT
/* Function to reset all counters to 0. */
extern void __gcov_reset (void);
-/* Function to enable early write of profile information so far. */
-extern void __gcov_dump (void);
+/* Function to enable early write of profile information so far.
+ __GCOV_DUMP is also used by __GCOV_DUMP_ALL. The latter
+ depends on __GCOV_DUMP to have hidden or protected visibility
+ so that each library has its own copy of the registered dumper. */
+extern void __gcov_dump (void) ATTRIBUTE_HIDDEN;
+
+/* Call __gcov_dump registered from each shared library. */
+void __gcov_dump_all (void);
/* The merge function that just sums the counters. */
extern void __gcov_merge_add (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
Index: libgcc/ChangeLog
===================================================================
--- libgcc/ChangeLog (revision 212682)
+++ libgcc/ChangeLog (working copy)
@@ -1,3 +1,9 @@
+2014-07-18 Xinliang David Li <davi...@google.com>
+
+ * libgcov-driver.c: Force __gcov_dump to be exported
+ * libgcov-interface.c (register_dumper): New function.
+ (__gcov_dump_all): Ditto.
+
2014-07-14 Richard Biener <rguent...@suse.de>
* libgcov.h (struct gcov_fn_info): Make ctrs size 1.
Index: libgcc/libgcov-driver.c
===================================================================
--- libgcc/libgcov-driver.c (revision 212682)
+++ libgcc/libgcov-driver.c (working copy)
@@ -55,6 +55,13 @@ extern void set_gcov_dump_complete (void
extern void reset_gcov_dump_complete (void) ATTRIBUTE_HIDDEN;
extern int get_gcov_dump_complete (void) ATTRIBUTE_HIDDEN;
extern void set_gcov_list (struct gcov_info *) ATTRIBUTE_HIDDEN;
+
+#ifndef IN_GCOV_TOOL
+
+/* Creates strong reference to force _gcov_dump.o to be linked
+ in shared library for exported interfaces. */
+void (*__gcov_dummy_ref)(void) = &__gcov_dump;
+#endif
struct gcov_fn_buffer
{
Index: libgcc/libgcov-interface.c
===================================================================
--- libgcc/libgcov-interface.c (revision 212682)
+++ libgcc/libgcov-interface.c (working copy)
@@ -115,6 +115,100 @@ __gcov_dump (void)
set_gcov_dump_complete ();
}
+typedef void (*gcov_dumper_type) (void);
+struct dumper_entry
+{
+ gcov_dumper_type dumper;
+ struct dumper_entry *next_dumper;
+};
+
+static struct dumper_entry this_dumper = {&__gcov_dump, 0};
+
+/* global dumper list with default visibilty. */
+struct dumper_entry *__gcov_dumper_list;
+
+#ifdef __GTHREAD_MUTEX_INIT
+__gthread_mutex_t __gcov_dump_mx = __GTHREAD_MUTEX_INIT;
+#define init_mx_once()
+#else
+__gthread_mutex_t __gcov_dump_mx;
+
+static void
+init_mx (void)
+{
+ __GTHREAD_MUTEX_INIT_FUNCTION (&__gcov_dump_mx);
+}
+static void
+init_mx_once (void)
+{
+ static __gthread_once_t once = __GTHREAD_ONCE_INIT;
+ __gthread_once (&once, init_mx);
+}
+#endif
+
+/* Register the library private __gcov_dump method
+ to the global list. */
+
+__attribute__((constructor))
+static void
+register_dumper (void)
+{
+ init_mx_once ();
+ __gthread_mutex_lock (&__gcov_dump_mx);
+ this_dumper.next_dumper = __gcov_dumper_list;
+ __gcov_dumper_list = &this_dumper;
+ __gthread_mutex_unlock (&__gcov_dump_mx);
+}
+
+__attribute__((destructor))
+static void
+unregister_dumper (void)
+{
+ struct dumper_entry *dumper;
+ struct dumper_entry *prev_dumper = 0;
+
+ init_mx_once ();
+ __gthread_mutex_lock (&__gcov_dump_mx);
+ dumper = __gcov_dumper_list;
+
+ while (dumper)
+ {
+ if (dumper->dumper == &__gcov_dump)
+ {
+ if (prev_dumper)
+ prev_dumper->next_dumper = dumper->next_dumper;
+ else
+ __gcov_dumper_list = dumper->next_dumper;
+ break;
+ }
+ prev_dumper = dumper;
+ dumper = dumper->next_dumper;
+ }
+ __gthread_mutex_unlock (&__gcov_dump_mx);
+}
+
+/* Public interface to dump profile data for all shared libraries
+ via registered dumpers from the libraries. This interface
+ has default visibility (unlike gcov_dump which has hidden
+ visbility. */
+
+void
+__gcov_dump_all (void)
+{
+ struct dumper_entry *dumper;
+
+ init_mx_once ();
+ __gthread_mutex_lock (&__gcov_dump_mx);
+
+ dumper = __gcov_dumper_list;
+ while (dumper)
+ {
+ dumper->dumper ();
+ dumper = dumper->next_dumper;
+ }
+ __gthread_mutex_unlock (&__gcov_dump_mx);
+}
+
#endif /* L_gcov_dump */
