Fix bug 4994 hangs on read(). I have tested the patch extensibly on ARM/LT.old.

Thank you Chase Douglas for reporting it and for the patch.

2 files changed, 80 insertions, 8 deletions

diff --git a/libpthread/linuxthreads.old/ptfork.c b/libpthread/linuxthreads.old/ptfork.c
index c34ea8104..7a5749efc 100644
--- a/libpthread/linuxthreads.old/ptfork.c
+++ b/libpthread/linuxthreads.old/ptfork.c
@@ -20,6 +20,7 @@
 
 #ifdef __ARCH_USE_MMU__
 
+#include <bits/uClibc_mutex.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -36,6 +37,16 @@ static struct handler_list * pthread_atfork_prepare = NULL;
 static struct handler_list * pthread_atfork_parent = NULL;
 static struct handler_list * pthread_atfork_child = NULL;
 
+#ifdef __MALLOC__
+__UCLIBC_MUTEX_EXTERN(__malloc_heap_lock);
+__UCLIBC_MUTEX_EXTERN(__malloc_sbrk_lock);
+#ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__
+__UCLIBC_MUTEX_EXTERN(__malloc_mmb_heap_lock);
+#endif
+#elif defined(__MALLOC_STANDARD__) || defined(__MALLOC_SIMPLE__)
+__UCLIBC_MUTEX_EXTERN(__malloc_lock);
+#endif
+
 static void pthread_insert_list(struct handler_list ** list,
                                 void (*handler)(void),
                                 struct handler_list * newlist,
@@ -78,6 +89,10 @@ static __inline__ void pthread_call_handlers(struct handler_list * list)
   for (/*nothing*/; list != NULL; list = list->next) (list->handler)();
 }
 
+void __pthread_once_fork_prepare(void);
+void __pthread_once_fork_child(void);
+void __pthread_once_fork_parent(void);
+
 extern __typeof(fork) __libc_fork;
 
 pid_t __fork(void) attribute_hidden;
@@ -90,14 +105,47 @@ pid_t __fork(void)
   prepare = pthread_atfork_prepare;
   child = pthread_atfork_child;
   parent = pthread_atfork_parent;
-  __pthread_mutex_unlock(&pthread_atfork_lock);
   pthread_call_handlers(prepare);
+
+  __pthread_once_fork_prepare();
+#ifdef __MALLOC__
+  __pthread_mutex_lock(&__malloc_sbrk_lock);
+  __pthread_mutex_lock(&__malloc_heap_lock);
+#ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__
+  __pthread_mutex_lock(&__malloc_mmb_heap_lock);
+#endif
+#elif defined(__MALLOC_STANDARD__) || defined(__MALLOC_SIMPLE__)
+  __pthread_mutex_lock(&__malloc_lock);
+#endif
+
   pid = __libc_fork();
   if (pid == 0) {
+#if defined(__MALLOC_STANDARD__) || defined(__MALLOC_SIMPLE__)
+    __libc_lock_init_recursive(__malloc_lock);
+#elif defined(__MALLOC__)
+#ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__
+    __libc_lock_init_adaptive(__malloc_mmb_heap_lock);
+#endif
+    __libc_lock_init_adaptive(__malloc_heap_lock);
+    __libc_lock_init(__malloc_sbrk_lock);
+#endif
+    __libc_lock_init_adaptive(pthread_atfork_lock);
     __pthread_reset_main_thread();
     __fresetlockfiles();
+    __pthread_once_fork_child();
     pthread_call_handlers(child);
   } else {
+#if defined(__MALLOC_STANDARD__) || defined(__MALLOC_SIMPLE__)
+    __pthread_mutex_unlock(&__malloc_lock);
+#elif defined(__MALLOC__)
+#ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__
+    __pthread_mutex_unlock(&__malloc_mmb_heap_lock);
+#endif
+    __pthread_mutex_unlock(&__malloc_heap_lock);
+    __pthread_mutex_unlock(&__malloc_sbrk_lock);
+#endif
+    __pthread_mutex_unlock(&pthread_atfork_lock);
+    __pthread_once_fork_parent();
     pthread_call_handlers(parent);
   }
   return pid;
diff --git a/libpthread/linuxthreads.old/sysdeps/pthread/bits/libc-lock.h b/libpthread/linuxthreads.old/sysdeps/pthread/bits/libc-lock.h
index 740e793be..78593ac11 100644
--- a/libpthread/linuxthreads.old/sysdeps/pthread/bits/libc-lock.h
+++ b/libpthread/linuxthreads.old/sysdeps/pthread/bits/libc-lock.h
@@ -30,7 +30,7 @@
 /* Mutex type.  */
 #if defined(_LIBC) || defined(_IO_MTSAFE_IO)
 typedef pthread_mutex_t __libc_lock_t;
-typedef struct { pthread_mutex_t mutex; } __libc_lock_recursive_t;
+typedef pthread_mutex_t __libc_lock_recursive_t;
 # ifdef __USE_UNIX98
 typedef pthread_rwlock_t __libc_rwlock_t;
 # else
@@ -132,15 +132,39 @@ typedef pthread_key_t __libc_key_t;
 #define __libc_rwlock_init(NAME) \
   (__libc_maybe_call (__pthread_rwlock_init, (&(NAME), NULL), 0));
 
+/* Same as last but this time we initialize an adaptive mutex.  */
+#if defined _LIBC && !defined NOT_IN_libc && defined SHARED
+#define __libc_lock_init_adaptive(NAME) \
+  ({									      \
+    (NAME).__m_count = 0;						      \
+    (NAME).__m_owner = NULL;						      \
+    (NAME).__m_kind = PTHREAD_MUTEX_ADAPTIVE_NP;			      \
+    (NAME).__m_lock.__status = 0;					      \
+    (NAME).__m_lock.__spinlock = __LT_SPINLOCK_INIT;			      \
+    0; })
+#else
+#define __libc_lock_init_adaptive(NAME) \
+  do {									      \
+    if (__pthread_mutex_init != NULL)					      \
+      {									      \
+	pthread_mutexattr_t __attr;					      \
+	__pthread_mutexattr_init (&__attr);				      \
+	__pthread_mutexattr_settype (&__attr, PTHREAD_MUTEX_ADAPTIVE_NP);     \
+	__pthread_mutex_init (&(NAME), &__attr);			      \
+	__pthread_mutexattr_destroy (&__attr);				      \
+      }									      \
+  } while (0);
+#endif
+
 /* Same as last but this time we initialize a recursive mutex.  */
 #if defined _LIBC && !defined NOT_IN_libc && defined SHARED
 #define __libc_lock_init_recursive(NAME) \
   ({									      \
-    (NAME).mutex.__m_count = 0;						      \
-    (NAME).mutex.__m_owner = NULL;					      \
-    (NAME).mutex.__m_kind = PTHREAD_MUTEX_RECURSIVE_NP;			      \
-    (NAME).mutex.__m_lock.__status = 0;					      \
-    (NAME).mutex.__m_lock.__spinlock = __LT_SPINLOCK_INIT;		      \
+    (NAME).__m_count = 0;						      \
+    (NAME).__m_owner = NULL;					      \
+    (NAME).__m_kind = PTHREAD_MUTEX_RECURSIVE_NP;			      \
+    (NAME).__m_lock.__status = 0;					      \
+    (NAME).__m_lock.__spinlock = __LT_SPINLOCK_INIT;		      \
     0; })
 #else
 #define __libc_lock_init_recursive(NAME) \
@@ -150,7 +174,7 @@ typedef pthread_key_t __libc_key_t;
 	pthread_mutexattr_t __attr;					      \
 	__pthread_mutexattr_init (&__attr);				      \
 	__pthread_mutexattr_settype (&__attr, PTHREAD_MUTEX_RECURSIVE_NP); \
-	__pthread_mutex_init (&(NAME).mutex, &__attr);			      \
+	__pthread_mutex_init (&(NAME), &__attr);			      \
 	__pthread_mutexattr_destroy (&__attr);				      \
       }									      \
   } while (0);