htl: Fix cleaning the reply port

If any RPC fails, the reply port will already be deallocated.
__pthread_thread_terminate thus has to defer taking its name until the very last
__thread_terminate_release which doesn't reply a message.  But then we
have to read from the pthread structure.

This introduces __pthread_dealloc_finish() which does the recording of
the thread termination, so the slot can be reused really only just before
the __thread_terminate_release call. Only the real thread can set it, so
let's decouple this from the pthread_state by just removing the
PTHREAD_TERMINATED state and add a terminated field.

diff --git a/htl/pt-alloc.c b/htl/pt-alloc.c
index 4b012a0c32b32c6fd2c9ab45225cb400c1143099..f6ab201812f7f911c21824d9a82d2ec0421b1371 100644 (file)
--- a/htl/pt-alloc.c
+++ b/htl/pt-alloc.c
@@ -54,6 +54,7 @@ initialize_pthread (struct __pthread *new)
 
   new->state_lock = (pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER;
   new->state_cond = (pthread_cond_t) PTHREAD_COND_INITIALIZER;
+  new->terminated = FALSE;
 
   memset (&new->res_state, '\0', sizeof (new->res_state));
 
@@ -84,10 +85,10 @@ __pthread_alloc (struct __pthread **pthread)
     {
       /* There is no need to take NEW->STATE_LOCK: if NEW is on this
          list, then it is protected by __PTHREAD_FREE_THREADS_LOCK
-         except in __pthread_dealloc where after it is added to the
+         except in __pthread_dealloc_finish where after it is added to the
          list (with the lock held), it drops the lock and then sets
          NEW->STATE and immediately stops using NEW.  */
-      if (new->state == PTHREAD_TERMINATED)
+      if (new->terminated)
        {
          __pthread_dequeue (new);
          break;

diff --git a/htl/pt-create.c b/htl/pt-create.c
index f8a1d2114704eb7357f5288a39d0d90165b2a465..ce52ed9f52210a4e4c7a049ebee817ec9ccfeeb1 100644 (file)
--- a/htl/pt-create.c
+++ b/htl/pt-create.c
@@ -256,7 +256,10 @@ __pthread_create_internal (struct __pthread **thread,
 failed_starting:
   /* If joinable, a reference was added for the caller.  */
   if (pthread->state == PTHREAD_JOINABLE)
-    __pthread_dealloc (pthread);
+    {
+      __pthread_dealloc (pthread);
+      __pthread_dealloc_finish (pthread);
+    }
 
   __pthread_setid (pthread->thread, NULL);
   atomic_decrement (&__pthread_total);
@@ -278,6 +281,7 @@ failed_thread_alloc:
                              / __vm_page_size) * __vm_page_size + stacksize);
 failed_stack_alloc:
   __pthread_dealloc (pthread);
+  __pthread_dealloc_finish (pthread);
 failed:
   return err;
 }

diff --git a/htl/pt-dealloc.c b/htl/pt-dealloc.c
index 9cca718c7f256c21d21d5b34c83e2b2a95c9d0fa..c776e3471dc376977ca7058f0d143f0a842d5799 100644 (file)
--- a/htl/pt-dealloc.c
+++ b/htl/pt-dealloc.c
@@ -29,12 +29,10 @@ extern struct __pthread *__pthread_free_threads;
 extern pthread_mutex_t __pthread_free_threads_lock;
 
 
-/* Deallocate the thread structure for PTHREAD.  */
+/* Deallocate the content of the thread structure for PTHREAD.  */
 void
 __pthread_dealloc (struct __pthread *pthread)
 {
-  assert (pthread->state != PTHREAD_TERMINATED);
-
   if (!atomic_decrement_and_test (&pthread->nr_refs))
     return;
 
@@ -56,13 +54,18 @@ __pthread_dealloc (struct __pthread *pthread)
   __pthread_mutex_lock (&__pthread_free_threads_lock);
   __pthread_enqueue (&__pthread_free_threads, pthread);
   __pthread_mutex_unlock (&__pthread_free_threads_lock);
+}
 
-  /* Setting PTHREAD->STATE to PTHREAD_TERMINATED makes this TCB
+/* Confirm deallocation of the thread structure for PTHREAD.  */
+void
+__pthread_dealloc_finish (struct __pthread *pthread)
+{
+  /* Setting PTHREAD->TERMINATED makes this TCB
      available for reuse.  After that point, we can no longer assume
      that PTHREAD is valid.
 
      Note that it is safe to not lock this update to PTHREAD->STATE:
      the only way that it can now be accessed is in __pthread_alloc,
      which reads this variable.  */
-  pthread->state = PTHREAD_TERMINATED;
+  pthread->terminated = TRUE;
 }

diff --git a/htl/pt-detach.c b/htl/pt-detach.c
index 97017ed8f270cb1e778325d2b83a36d6acf94c50..cb611f1b8f9c0ad08c65e98c40e6bc53abc25fc4 100644 (file)
--- a/htl/pt-detach.c
+++ b/htl/pt-detach.c
@@ -62,12 +62,6 @@ __pthread_detach (pthread_t thread)
       __pthread_dealloc (pthread);
       break;
 
-    case PTHREAD_TERMINATED:
-      /* Pretend THREAD wasn't there in the first place.  */
-      __pthread_mutex_unlock (&pthread->state_lock);
-      err = ESRCH;
-      break;
-
     default:
       /* Thou shalt not detach non-joinable threads!  */
       __pthread_mutex_unlock (&pthread->state_lock);

diff --git a/htl/pt-internal.h b/htl/pt-internal.h
index 738efd5c6f286d8b9f9fbbf2b033f7093fcc5282..f01cb7ceb292b323b16dd09a38ad488f822e5e77 100644 (file)
--- a/htl/pt-internal.h
+++ b/htl/pt-internal.h
@@ -48,8 +48,6 @@ enum pthread_state
   PTHREAD_DETACHED,
   /* A joinable thread exited and its return code is available.  */
   PTHREAD_EXITED,
-  /* The thread structure is unallocated and available for reuse.  */
-  PTHREAD_TERMINATED
 };
 
 #ifndef PTHREAD_KEY_MEMBERS
@@ -95,6 +93,8 @@ struct __pthread
   enum pthread_state state;
   pthread_mutex_t state_lock;  /* Locks the state.  */
   pthread_cond_t state_cond;   /* Signalled when the state changes.  */
+  bool terminated;             /* Whether the kernel thread is over
+                                  and we can reuse this structure.  */
 
   /* Resolver state.  */
   struct __res_state res_state;
@@ -209,12 +209,18 @@ extern int __pthread_create_internal (struct __pthread **__restrict pthread,
    kernel thread or a stack).  THREAD has one reference.  */
 extern int __pthread_alloc (struct __pthread **thread);
 
-/* Deallocate the thread structure.  This is the dual of
+/* Deallocate the content of the thread structure.  This is the dual of
    __pthread_alloc (N.B. it does not call __pthread_stack_dealloc nor
-   __pthread_thread_terminate).  THREAD loses one reference and is
-   released if the reference counter drops to 0.  */
+   __pthread_thread_terminate).  THREAD loses one reference, and if
+   if the reference counter drops to 0 this returns 1, and the caller has
+   to call __pthread_dealloc_finish when it is really finished with using
+   THREAD.  */
 extern void __pthread_dealloc (struct __pthread *thread);
 
+/* Confirm deallocating the thread structure.  Before calling this
+   the structure will not be reused yet.  */
+extern void __pthread_dealloc_finish (struct __pthread *pthread);
+
 
 /* Allocate a stack of size STACKSIZE.  The stack base shall be
    returned in *STACKADDR.  */

diff --git a/htl/pt-join.c b/htl/pt-join.c
index 203e649d5eaa10bf59c693b867578417e3d200b1..45268134d00930195b44eda09917e5001e72c620 100644 (file)
--- a/htl/pt-join.c
+++ b/htl/pt-join.c
@@ -75,12 +75,6 @@ __pthread_join_common (pthread_t thread, void **status, int try,
       __pthread_dealloc (pthread);
       break;
 
-    case PTHREAD_TERMINATED:
-      /* Pretend THREAD wasn't there in the first place.  */
-      __pthread_mutex_unlock (&pthread->state_lock);
-      err = ESRCH;
-      break;
-
     default:
       /* Thou shalt not join non-joinable threads!  */
       __pthread_mutex_unlock (&pthread->state_lock);

diff --git a/sysdeps/mach/htl/pt-thread-terminate.c b/sysdeps/mach/htl/pt-thread-terminate.c
index 9bd6c3434d083d13d6092f3c02d9a4a948963533..eb60aa057cd744db6c18cc59dd37a74a2fd52193 100644 (file)
--- a/sysdeps/mach/htl/pt-thread-terminate.c
+++ b/sysdeps/mach/htl/pt-thread-terminate.c
@@ -35,6 +35,7 @@ __pthread_thread_terminate (struct __pthread *thread)
   void *stackaddr;
   size_t stacksize;
   error_t err;
+  int self;
 
   kernel_thread = thread->kernel_thread;
 
@@ -52,25 +53,32 @@ __pthread_thread_terminate (struct __pthread *thread)
 
   wakeup_port = thread->wakeupmsg.msgh_remote_port;
 
-  /* Each thread has its own reply port, allocated from MiG stub code calling
-     __mig_get_reply_port.  Destroying it is a bit tricky because the calls
-     involved are also RPCs, causing the creation of a new reply port if
-     currently null. The __thread_terminate_release call is actually a one way
-     simple routine designed not to require a reply port.  */
   self_ktid = __mach_thread_self ();
-  reply_port = (self_ktid == kernel_thread)
-      ? __mig_get_reply_port () : MACH_PORT_NULL;
+  self = self_ktid == kernel_thread;
   __mach_port_deallocate (__mach_task_self (), self_ktid);
 
   /* The kernel thread won't be there any more.  */
   thread->kernel_thread = MACH_PORT_DEAD;
 
-  /* Finally done with the thread structure.  */
+  /* Release thread resources.  */
   __pthread_dealloc (thread);
 
-  /* The wake up port is now no longer needed.  */
+  /* The wake up port (needed for locks in __pthread_dealloc) is now no longer
+     needed.  */
   __mach_port_destroy (__mach_task_self (), wakeup_port);
 
+  /* Each thread has its own reply port, allocated from MiG stub code calling
+     __mig_get_reply_port.  Destroying it is a bit tricky because the calls
+     involved are also RPCs, causing the creation of a new reply port if
+     currently null. The __thread_terminate_release call is actually a one way
+     simple routine designed not to require a reply port.  */
+  reply_port = self ? __mig_get_reply_port () : MACH_PORT_NULL;
+  /* From here we shall not use a MIG reply port any more.  */
+
+  /* Finally done with the thread structure (we still needed it to access the
+     reply port).  */
+  __pthread_dealloc_finish (thread);
+
   /* Terminate and release all that's left.  */
   err = __thread_terminate_release (kernel_thread, mach_task_self (),
                                    kernel_thread, reply_port,