Fix the collector hang when it is configured with --enable-gc-debug

Issue #205 (bdwgc).

* dbg_mlc.c (GC_store_debug_info_inner): Remove comment (as it exists
in the header); change from STATIC to GC_INNER.
* dbg_mlc.c (STORE_DEBUG_INFO): New macro.
* dbg_mlc.c (GC_store_debug_info): Change from GC_INNER to static;
remove GC_ prefix; replace ptr_t to void*; add fn argument;
replace "const char *string, int linenum" with GC_EXTRA_PARAMS;
change "word sz" argument to "size_t lb"; allow p to be null (print
error message in this case); call GC_start_debugging_inner unless
GC_debugging_started; call ADD_CALL_CHAIN.
* dbg_mlc.c (GC_start_debugging): Remove.
* dbg_mlc.c (GC_debug_malloc, GC_debug_malloc_ignore_off_page,
GC_debug_malloc_atomic_ignore_off_page, GC_debug_generic_malloc,
GC_debug_malloc_atomic, GC_debug_malloc_uncollectable): Call
STORE_DEBUG_INFO() instead of checking result for null and calling
GC_start_debugging, ADD_CALL_CHAIN, GC_store_debug_info.
* dbg_mlc.c [STUBBORN_ALLOC] (GC_debug_malloc_stubborn): Likewise.
* dbg_mlc.c [GC_ATOMIC_UNCOLLECTABLE]
(GC_debug_malloc_atomic_uncollectable): Likewise.
* gcj_mlc.c [GC_GCJ_SUPPORT] (GC_debug_gcj_malloc): Call ADD_CALL_CHAIN
while holding the lock; call GC_store_debug_info_inner (holding the
lock) instead of GC_store_debug_info.
* include/private/dbg_mlc.h (ADD_CALL_CHAIN): Update comment.
* include/private/gc_priv.h (GC_store_debug_info): Replace with
GC_store_debug_info_inner; update comment; change ptr_t to void*.
* os_dep.c [SAVE_CALL_CHAIN] (GC_save_callers): Add assertion that the
allocation lock is held; add comment.

diff --git a/dbg_mlc.c b/dbg_mlc.c
index 610728d..77497eb 100644 (file)
--- a/dbg_mlc.c
+++ b/dbg_mlc.c
@@ -272,10 +272,8 @@
 # define CROSSES_HBLK(p, sz) \
         (((word)((p) + sizeof(oh) + (sz) - 1) ^ (word)(p)) >= HBLKSIZE)
 
-/* Store debugging info into p.  Return displaced pointer.         */
-/* This version assumes we do hold the allocation lock.            */
-STATIC void *GC_store_debug_info_inner(void *p, word sz GC_ATTR_UNUSED,
-                                       const char *string, int linenum)
+GC_INNER void *GC_store_debug_info_inner(void *p, word sz GC_ATTR_UNUSED,
+                                         const char *string, int linenum)
 {
     word * result = (word *)((oh *)p + 1);
 
@@ -298,14 +296,29 @@ STATIC void *GC_store_debug_info_inner(void *p, word sz GC_ATTR_UNUSED,
     return result;
 }
 
-GC_INNER ptr_t GC_store_debug_info(ptr_t p, word sz, const char *string,
-                                   int linenum)
+/* Check the allocation is successful, store debugging info into p,     */
+/* start the debugging mode (if not yet), and return displaced pointer. */
+#ifdef GC_ADD_CALLER
+# define STORE_DEBUG_INFO(p, lb, fn) store_debug_info(p, lb, fn, ra, s, i)
+#else
+# define STORE_DEBUG_INFO(p, lb, fn) store_debug_info(p, lb, fn, s, i)
+#endif
+static void *store_debug_info(void *p, size_t lb,
+                              const char *fn, GC_EXTRA_PARAMS)
 {
-    ptr_t result;
+    void *result;
     DCL_LOCK_STATE;
 
+    if (NULL == p) {
+        GC_err_printf("%s(%lu) returning NULL (%s:%d)\n",
+                      fn, (unsigned long)lb, s, i);
+        return NULL;
+    }
     LOCK();
-    result = (ptr_t)GC_store_debug_info_inner(p, sz, string, linenum);
+    if (!GC_debugging_started)
+        GC_start_debugging_inner();
+    ADD_CALL_CHAIN(p, ra);
+    result = GC_store_debug_info_inner(p, (word)lb, s, i);
     UNLOCK();
     return result;
 }
@@ -485,20 +498,6 @@ GC_INNER void GC_start_debugging_inner(void)
   GC_register_displacement_inner((word)sizeof(oh));
 }
 
-#ifdef THREADS
-  STATIC void GC_start_debugging(void)
-  {
-    DCL_LOCK_STATE;
-
-    LOCK();
-    if (!GC_debugging_started)
-      GC_start_debugging_inner();
-    UNLOCK();
-  }
-#else
-# define GC_start_debugging GC_start_debugging_inner
-#endif /* !THREADS */
-
 size_t GC_debug_header_size = sizeof(oh);
 
 GC_API void GC_CALL GC_debug_register_displacement(size_t offset)
@@ -546,16 +545,7 @@ GC_API GC_ATTR_MALLOC void * GC_CALL GC_debug_malloc(size_t lb,
         GC_caller_func_offset(ra, &s, &i);
       }
 #   endif
-    if (result == 0) {
-        GC_err_printf("GC_debug_malloc(%lu) returning NULL (%s:%d)\n",
-                      (unsigned long)lb, s, i);
-        return(0);
-    }
-    if (!GC_debugging_started) {
-        GC_start_debugging();
-    }
-    ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    return STORE_DEBUG_INFO(result, lb, "GC_debug_malloc");
 }
 
 GC_API GC_ATTR_MALLOC void * GC_CALL
@@ -563,16 +553,7 @@ GC_API GC_ATTR_MALLOC void * GC_CALL
 {
     void * result = GC_malloc_ignore_off_page(SIZET_SAT_ADD(lb, DEBUG_BYTES));
 
-    if (result == 0) {
-        GC_err_printf("GC_debug_malloc_ignore_off_page(%lu)"
-                      " returning NULL (%s:%d)\n", (unsigned long)lb, s, i);
-        return(0);
-    }
-    if (!GC_debugging_started) {
-        GC_start_debugging();
-    }
-    ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    return STORE_DEBUG_INFO(result, lb, "GC_debug_malloc_ignore_off_page");
 }
 
 GC_API GC_ATTR_MALLOC void * GC_CALL
@@ -581,33 +562,15 @@ GC_API GC_ATTR_MALLOC void * GC_CALL
     void * result = GC_malloc_atomic_ignore_off_page(
                                 SIZET_SAT_ADD(lb, DEBUG_BYTES));
 
-    if (result == 0) {
-        GC_err_printf("GC_debug_malloc_atomic_ignore_off_page(%lu)"
-                      " returning NULL (%s:%d)\n", (unsigned long)lb, s, i);
-        return(0);
-    }
-    if (!GC_debugging_started) {
-        GC_start_debugging();
-    }
-    ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    return STORE_DEBUG_INFO(result, lb,
+                            "GC_debug_malloc_atomic_ignore_off_page");
 }
 
 STATIC void * GC_debug_generic_malloc(size_t lb, int knd, GC_EXTRA_PARAMS)
 {
     void * result = GC_generic_malloc(SIZET_SAT_ADD(lb, DEBUG_BYTES), knd);
 
-    if (NULL == result) {
-        GC_err_printf(
-                "GC_debug_generic_malloc(%lu, %d) returning NULL (%s:%d)\n",
-                (unsigned long)lb, knd, s, i);
-        return NULL;
-    }
-    if (!GC_debugging_started) {
-        GC_start_debugging();
-    }
-    ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    return STORE_DEBUG_INFO(result, lb, "GC_debug_generic_malloc");
 }
 
 #ifdef DBG_HDRS_ALL
@@ -658,16 +621,7 @@ STATIC void * GC_debug_generic_malloc(size_t lb, int knd, GC_EXTRA_PARAMS)
   {
     void * result = GC_malloc_stubborn(SIZET_SAT_ADD(lb, DEBUG_BYTES));
 
-    if (result == 0) {
-        GC_err_printf("GC_debug_malloc_stubborn(%lu)"
-                      " returning NULL (%s:%d)\n", (unsigned long)lb, s, i);
-        return(0);
-    }
-    if (!GC_debugging_started) {
-        GC_start_debugging();
-    }
-    ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    return STORE_DEBUG_INFO(result, lb, "GC_debug_malloc_stubborn");
   }
 
   GC_API void GC_CALL GC_debug_change_stubborn(const void *p)
@@ -721,16 +675,7 @@ GC_API GC_ATTR_MALLOC void * GC_CALL GC_debug_malloc_atomic(size_t lb,
 {
     void * result = GC_malloc_atomic(SIZET_SAT_ADD(lb, DEBUG_BYTES));
 
-    if (result == 0) {
-        GC_err_printf("GC_debug_malloc_atomic(%lu) returning NULL (%s:%d)\n",
-                      (unsigned long)lb, s, i);
-        return(0);
-    }
-    if (!GC_debugging_started) {
-        GC_start_debugging();
-    }
-    ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    return STORE_DEBUG_INFO(result, lb, "GC_debug_malloc_atomic");
 }
 
 GC_API GC_ATTR_MALLOC char * GC_CALL GC_debug_strdup(const char *str,
@@ -801,16 +746,7 @@ GC_API GC_ATTR_MALLOC void * GC_CALL GC_debug_malloc_uncollectable(size_t lb,
     void * result = GC_malloc_uncollectable(
                                 SIZET_SAT_ADD(lb, UNCOLLECTABLE_DEBUG_BYTES));
 
-    if (result == 0) {
-        GC_err_printf("GC_debug_malloc_uncollectable(%lu)"
-                      " returning NULL (%s:%d)\n", (unsigned long)lb, s, i);
-        return(0);
-    }
-    if (!GC_debugging_started) {
-        GC_start_debugging();
-    }
-    ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    return STORE_DEBUG_INFO(result, lb, "GC_debug_malloc_uncollectable");
 }
 
 #ifdef GC_ATOMIC_UNCOLLECTABLE
@@ -820,16 +756,8 @@ GC_API GC_ATTR_MALLOC void * GC_CALL GC_debug_malloc_uncollectable(size_t lb,
     void * result = GC_malloc_atomic_uncollectable(
                                 SIZET_SAT_ADD(lb, UNCOLLECTABLE_DEBUG_BYTES));
 
-    if (result == 0) {
-        GC_err_printf("GC_debug_malloc_atomic_uncollectable(%lu)"
-                      " returning NULL (%s:%d)\n", (unsigned long)lb, s, i);
-        return(0);
-    }
-    if (!GC_debugging_started) {
-        GC_start_debugging();
-    }
-    ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    return STORE_DEBUG_INFO(result, lb,
+                            "GC_debug_malloc_atomic_uncollectable");
   }
 #endif /* GC_ATOMIC_UNCOLLECTABLE */
 

diff --git a/gcj_mlc.c b/gcj_mlc.c
index 55af7a0..35b3d3f 100644 (file)
--- a/gcj_mlc.c
+++ b/gcj_mlc.c
@@ -223,9 +223,10 @@ GC_API GC_ATTR_MALLOC void * GC_CALL GC_debug_gcj_malloc(size_t lb,
     if (!GC_debugging_started) {
         GC_start_debugging_inner();
     }
-    UNLOCK();
     ADD_CALL_CHAIN(result, ra);
-    return GC_store_debug_info((ptr_t)result, (word)lb, s, i);
+    result = GC_store_debug_info_inner(result, (word)lb, s, i);
+    UNLOCK();
+    return result;
 }
 
 /* There is no THREAD_LOCAL_ALLOC for GC_gcj_malloc_ignore_off_page().  */

diff --git a/include/private/dbg_mlc.h b/include/private/dbg_mlc.h
index 02c9511..69cf95c 100644 (file)
--- a/include/private/dbg_mlc.h
+++ b/include/private/dbg_mlc.h
@@ -123,8 +123,7 @@ typedef struct {
 #define SIMPLE_ROUNDED_UP_WORDS(n) BYTES_TO_WORDS((n) + WORDS_TO_BYTES(1) - 1)
 
 /* ADD_CALL_CHAIN stores a (partial) call chain into an object  */
-/* header.  It may be called with or without the allocation     */
-/* lock.                                                        */
+/* header; it should be called with the allocation lock held.   */
 /* PRINT_CALL_CHAIN prints the call chain stored in an object   */
 /* to stderr.  It requires that we do not hold the lock.        */
 #if defined(SAVE_CALL_CHAIN)

diff --git a/include/private/gc_priv.h b/include/private/gc_priv.h
index 002945c..1d682a9 100644 (file)
--- a/include/private/gc_priv.h
+++ b/include/private/gc_priv.h
@@ -2392,9 +2392,9 @@ GC_INNER void GC_start_debugging_inner(void);   /* defined in dbg_mlc.c. */
                         /* Should not be called if GC_debugging_started. */
 
 /* Store debugging info into p.  Return displaced pointer.      */
-/* Assumes we don't hold allocation lock.                       */
-GC_INNER ptr_t GC_store_debug_info(ptr_t p, word sz, const char *str,
-                                   int linenum);
+/* Assumes we hold the allocation lock.                         */
+GC_INNER void *GC_store_debug_info_inner(void *p, word sz, const char *str,
+                                         int linenum);
 
 #ifdef REDIRECT_MALLOC
 # ifdef GC_LINUX_THREADS

diff --git a/os_dep.c b/os_dep.c
index 75dc95b..b10e9e9 100644 (file)
--- a/os_dep.c
+++ b/os_dep.c
@@ -4664,6 +4664,12 @@ GC_INNER void GC_save_callers(struct callinfo info[NFRAMES])
     }
     GC_in_save_callers = TRUE;
 # endif
+
+  GC_ASSERT(I_HOLD_LOCK());
+                /* backtrace may call dl_iterate_phdr which is also     */
+                /* used by GC_register_dynamic_libraries, and           */
+                /* dl_iterate_phdr is not guaranteed to be reentrant.   */
+
   GC_STATIC_ASSERT(sizeof(struct callinfo) == sizeof(void *));
   npcs = backtrace((void **)tmp_info, NFRAMES + IGNORE_FRAMES);
   if (npcs > IGNORE_FRAMES)