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synced 2024-11-21 12:30:06 +00:00
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.
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e22a4557eb
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@ -54,6 +54,7 @@ initialize_pthread (struct __pthread *new)
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new->state_lock = (pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER;
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new->state_cond = (pthread_cond_t) PTHREAD_COND_INITIALIZER;
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new->terminated = FALSE;
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memset (&new->res_state, '\0', sizeof (new->res_state));
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@ -84,10 +85,10 @@ __pthread_alloc (struct __pthread **pthread)
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{
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/* There is no need to take NEW->STATE_LOCK: if NEW is on this
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list, then it is protected by __PTHREAD_FREE_THREADS_LOCK
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except in __pthread_dealloc where after it is added to the
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except in __pthread_dealloc_finish where after it is added to the
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list (with the lock held), it drops the lock and then sets
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NEW->STATE and immediately stops using NEW. */
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if (new->state == PTHREAD_TERMINATED)
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if (new->terminated)
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{
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__pthread_dequeue (new);
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break;
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@ -256,7 +256,10 @@ __pthread_create_internal (struct __pthread **thread,
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failed_starting:
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/* If joinable, a reference was added for the caller. */
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if (pthread->state == PTHREAD_JOINABLE)
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__pthread_dealloc (pthread);
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{
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__pthread_dealloc (pthread);
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__pthread_dealloc_finish (pthread);
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}
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__pthread_setid (pthread->thread, NULL);
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atomic_decrement (&__pthread_total);
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@ -278,6 +281,7 @@ failed_thread_alloc:
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/ __vm_page_size) * __vm_page_size + stacksize);
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failed_stack_alloc:
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__pthread_dealloc (pthread);
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__pthread_dealloc_finish (pthread);
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failed:
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return err;
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}
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@ -29,12 +29,10 @@ extern struct __pthread *__pthread_free_threads;
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extern pthread_mutex_t __pthread_free_threads_lock;
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/* Deallocate the thread structure for PTHREAD. */
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/* Deallocate the content of the thread structure for PTHREAD. */
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void
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__pthread_dealloc (struct __pthread *pthread)
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{
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assert (pthread->state != PTHREAD_TERMINATED);
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if (!atomic_decrement_and_test (&pthread->nr_refs))
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return;
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@ -56,13 +54,18 @@ __pthread_dealloc (struct __pthread *pthread)
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__pthread_mutex_lock (&__pthread_free_threads_lock);
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__pthread_enqueue (&__pthread_free_threads, pthread);
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__pthread_mutex_unlock (&__pthread_free_threads_lock);
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}
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/* Setting PTHREAD->STATE to PTHREAD_TERMINATED makes this TCB
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/* Confirm deallocation of the thread structure for PTHREAD. */
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void
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__pthread_dealloc_finish (struct __pthread *pthread)
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{
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/* Setting PTHREAD->TERMINATED makes this TCB
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available for reuse. After that point, we can no longer assume
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that PTHREAD is valid.
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Note that it is safe to not lock this update to PTHREAD->STATE:
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the only way that it can now be accessed is in __pthread_alloc,
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which reads this variable. */
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pthread->state = PTHREAD_TERMINATED;
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pthread->terminated = TRUE;
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}
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@ -62,12 +62,6 @@ __pthread_detach (pthread_t thread)
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__pthread_dealloc (pthread);
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break;
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case PTHREAD_TERMINATED:
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/* Pretend THREAD wasn't there in the first place. */
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__pthread_mutex_unlock (&pthread->state_lock);
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err = ESRCH;
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break;
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default:
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/* Thou shalt not detach non-joinable threads! */
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__pthread_mutex_unlock (&pthread->state_lock);
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@ -48,8 +48,6 @@ enum pthread_state
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PTHREAD_DETACHED,
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/* A joinable thread exited and its return code is available. */
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PTHREAD_EXITED,
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/* The thread structure is unallocated and available for reuse. */
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PTHREAD_TERMINATED
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};
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#ifndef PTHREAD_KEY_MEMBERS
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@ -95,6 +93,8 @@ struct __pthread
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enum pthread_state state;
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pthread_mutex_t state_lock; /* Locks the state. */
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pthread_cond_t state_cond; /* Signalled when the state changes. */
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bool terminated; /* Whether the kernel thread is over
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and we can reuse this structure. */
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/* Resolver state. */
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struct __res_state res_state;
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@ -209,12 +209,18 @@ extern int __pthread_create_internal (struct __pthread **__restrict pthread,
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kernel thread or a stack). THREAD has one reference. */
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extern int __pthread_alloc (struct __pthread **thread);
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/* Deallocate the thread structure. This is the dual of
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/* Deallocate the content of the thread structure. This is the dual of
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__pthread_alloc (N.B. it does not call __pthread_stack_dealloc nor
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__pthread_thread_terminate). THREAD loses one reference and is
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released if the reference counter drops to 0. */
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__pthread_thread_terminate). THREAD loses one reference, and if
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if the reference counter drops to 0 this returns 1, and the caller has
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to call __pthread_dealloc_finish when it is really finished with using
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THREAD. */
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extern void __pthread_dealloc (struct __pthread *thread);
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/* Confirm deallocating the thread structure. Before calling this
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the structure will not be reused yet. */
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extern void __pthread_dealloc_finish (struct __pthread *pthread);
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/* Allocate a stack of size STACKSIZE. The stack base shall be
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returned in *STACKADDR. */
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@ -75,12 +75,6 @@ __pthread_join_common (pthread_t thread, void **status, int try,
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__pthread_dealloc (pthread);
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break;
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case PTHREAD_TERMINATED:
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/* Pretend THREAD wasn't there in the first place. */
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__pthread_mutex_unlock (&pthread->state_lock);
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err = ESRCH;
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break;
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default:
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/* Thou shalt not join non-joinable threads! */
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__pthread_mutex_unlock (&pthread->state_lock);
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@ -35,6 +35,7 @@ __pthread_thread_terminate (struct __pthread *thread)
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void *stackaddr;
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size_t stacksize;
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error_t err;
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int self;
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kernel_thread = thread->kernel_thread;
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@ -52,25 +53,32 @@ __pthread_thread_terminate (struct __pthread *thread)
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wakeup_port = thread->wakeupmsg.msgh_remote_port;
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/* Each thread has its own reply port, allocated from MiG stub code calling
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__mig_get_reply_port. Destroying it is a bit tricky because the calls
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involved are also RPCs, causing the creation of a new reply port if
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currently null. The __thread_terminate_release call is actually a one way
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simple routine designed not to require a reply port. */
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self_ktid = __mach_thread_self ();
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reply_port = (self_ktid == kernel_thread)
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? __mig_get_reply_port () : MACH_PORT_NULL;
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self = self_ktid == kernel_thread;
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__mach_port_deallocate (__mach_task_self (), self_ktid);
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/* The kernel thread won't be there any more. */
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thread->kernel_thread = MACH_PORT_DEAD;
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/* Finally done with the thread structure. */
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/* Release thread resources. */
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__pthread_dealloc (thread);
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/* The wake up port is now no longer needed. */
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/* The wake up port (needed for locks in __pthread_dealloc) is now no longer
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needed. */
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__mach_port_destroy (__mach_task_self (), wakeup_port);
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/* Each thread has its own reply port, allocated from MiG stub code calling
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__mig_get_reply_port. Destroying it is a bit tricky because the calls
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involved are also RPCs, causing the creation of a new reply port if
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currently null. The __thread_terminate_release call is actually a one way
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simple routine designed not to require a reply port. */
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reply_port = self ? __mig_get_reply_port () : MACH_PORT_NULL;
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/* From here we shall not use a MIG reply port any more. */
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/* Finally done with the thread structure (we still needed it to access the
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reply port). */
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__pthread_dealloc_finish (thread);
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/* Terminate and release all that's left. */
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err = __thread_terminate_release (kernel_thread, mach_task_self (),
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kernel_thread, reply_port,
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