WebSVN – HelenOS – Diff – //branches/tracing/kernel/generic/src/ipc/ipc.c

 #include <proc/task.h>
 #include <memstr.h>
 #include <debug.h>
 #include <print.h>
+#include <console/klog.h>
 #include <proc/thread.h>
 #include <arch/interrupt.h>
 #include <ipc/irq.h>
 /** Open channel that is assigned automatically to new tasks */
         IPC_SET_RETVAL(call->data, EHANGUP);
         _ipc_answer_free_call(call);
+    }
+}
-/** Cleans up all IPC communication of the current task.
+/** Disconnects all phones connected to an answerbox.
+ *
- * Note: ipc_hangup sets returning answerbox to TASK->answerbox, you
+ * @param box       Answerbox to disconnect phones from.
- * have to change it as well if you want to cleanup other tasks than TASK.
+ * @param notify_box    If true, the answerbox will get a hangup message for
+ *          each disconnected phone.
  */
-void ipc_cleanup(void)
+static void ipc_answerbox_slam_phones(answerbox_t *box, bool notify_box)
+{
-    int i;
-    call_t *call;
     phone_t *phone;
     DEADLOCK_PROBE_INIT(p_phonelck);
+    ipl_t ipl;
+    call_t *call;
-    /* Disconnect all our phones ('ipc_phone_hangup') */
-    for (i = 0; i < IPC_MAX_PHONES; i++)
-        ipc_phone_hangup(&TASK->phones[i]);
-    /* Disconnect all connected irqs */
-    ipc_irq_cleanup(&TASK->answerbox);
+    call = ipc_call_alloc(0);
     /* Disconnect all phones connected to our answerbox */
 restart_phones:
+    ipl = interrupts_disable();
-    spinlock_lock(&TASK->answerbox.lock);
+    spinlock_lock(&box->lock);
-    while (!list_empty(&TASK->answerbox.connected_phones)) {
+    while (!list_empty(&box->connected_phones)) {
-        phone = list_get_instance(TASK->answerbox.connected_phones.next,
+        phone = list_get_instance(box->connected_phones.next,
             phone_t, link);
         if (!spinlock_trylock(&phone->lock)) {
-            spinlock_unlock(&TASK->answerbox.lock);
+            spinlock_unlock(&box->lock);
+            interrupts_restore(ipl);
             DEADLOCK_PROBE(p_phonelck, DEADLOCK_THRESHOLD);
             goto restart_phones;
+        }
         /* Disconnect phone */
         ASSERT(phone->state == IPC_PHONE_CONNECTED);
-        phone->state = IPC_PHONE_SLAMMED;
         list_remove(&phone->link);
+        phone->state = IPC_PHONE_SLAMMED;
+        if (notify_box) {
+            spinlock_unlock(&phone->lock);
+            spinlock_unlock(&box->lock);
+            interrupts_restore(ipl);
+            /*
+             * Send one message to the answerbox for each
+             * phone. Used to make sure the kbox thread
+             * wakes up after the last phone has been
+             * disconnected.
+             */
+            IPC_SET_METHOD(call->data, IPC_M_PHONE_HUNGUP);
+            call->flags |= IPC_CALL_DISCARD_ANSWER;
+            _ipc_call(phone, box, call);
+            /* Allocate another call in advance */
+            call = ipc_call_alloc(0);
+            /* Must start again */
+            goto restart_phones;
+        }
         spinlock_unlock(&phone->lock);
+    }
+    spinlock_unlock(&box->lock);
+    interrupts_restore(ipl);
+    /* Free unused call */
+    if (call) ipc_call_free(call);
+}
+static void ipc_kbox_cleanup()
+{
+    ipl_t ipl;
+    bool have_kb_thread;
+    /* Only hold kb_cleanup_lock while setting kb_finished - this is enough */
+    ipl = interrupts_disable();
+    spinlock_lock(&TASK->kb_cleanup_lock);
+    TASK->kb_finished = true;
+    spinlock_unlock(&TASK->kb_cleanup_lock);
+    interrupts_restore(ipl);
+    have_kb_thread = (TASK->kb_thread != NULL);
+    /* From now on nobody will try to connect phones or attach kbox threads */
+    /*
+     * Disconnect all phones connected to our kbox. Passing true for
+     * notify_box causes a HANGUP message to be inserted for each
+     * disconnected phone. This ensures the kbox thread is going to
+     * wake up and terminate.
+     */
+    ipc_answerbox_slam_phones(&TASK->kernel_box, have_kb_thread);
+    /* TODO: Wait for kbox thread to terminate */
+    if (have_kb_thread) {
+        klog_printf("ipc_kbox_cleanup - wait for kbox thread to finish");
+        waitq_sleep(&TASK->kb_thread_shutdown_wq);
+    }
+    /* Answer all messages in 'calls' and 'dispatched_calls' queues */
+    spinlock_lock(&TASK->kernel_box.lock);
+    ipc_cleanup_call_list(&TASK->kernel_box.dispatched_calls);
+    ipc_cleanup_call_list(&TASK->kernel_box.calls);
+    spinlock_unlock(&TASK->kernel_box.lock);
+}
+/** Cleans up all IPC communication of the current task.
+ *
+ * Note: ipc_hangup sets returning answerbox to TASK->answerbox, you
+ * have to change it as well if you want to cleanup other tasks than TASK.
+ */
+void ipc_cleanup(void)
+{
+    int i;
+    call_t *call;
+    /* Disconnect all our phones ('ipc_phone_hangup') */
+    for (i = 0; i < IPC_MAX_PHONES; i++)
+        ipc_phone_hangup(&TASK->phones[i]);
+    /* Disconnect all connected irqs */
+    ipc_irq_cleanup(&TASK->answerbox);
+    /* Disconnect all phones connected to our regular answerbox */
+    ipc_answerbox_slam_phones(&TASK->answerbox, false);
+    /* Clean up kbox thread and communications */
+    ipc_kbox_cleanup();
     /* Answer all messages in 'calls' and 'dispatched_calls' queues */
+    spinlock_lock(&TASK->answerbox.lock);
     ipc_cleanup_call_list(&TASK->answerbox.dispatched_calls);
     ipc_cleanup_call_list(&TASK->answerbox.calls);
     spinlock_unlock(&TASK->answerbox.lock);
     /* Wait for all async answers to arrive */
             if (method == IPC_M_DEBUG_ALL) {
                 udebug_call_receive(call);
+            }
             if (method == IPC_M_PHONE_HUNGUP) {
-                klog_printf("kbox: handle hangup message\n");
+                klog_printf("kbox: handle hangup message");
                 /* Was it our debugger, who hung up? */
                 if (call->sender == TASK->debugger) {
                     /* Terminate debugging session (if any) */
-                    klog_printf("kbox: terminate debug session\n");
+                    klog_printf("kbox: terminate debug session");
                     ipl = interrupts_disable();
                     spinlock_lock(&TASK->lock);
                     udebug_task_cleanup(TASK);
                     spinlock_unlock(&TASK->lock);
                     interrupts_restore(ipl);
                 } else {
-                    klog_printf("kbox: was not debugger\n");
+                    klog_printf("kbox: was not debugger");
+                }
-                klog_printf("kbox: continue with hangup message\n");
+                klog_printf("kbox: continue with hangup message");
                 IPC_SET_RETVAL(call->data, 0);
                 ipc_answer(&TASK->kernel_box, call);
                 ipl = interrupts_disable();
                 spinlock_lock(&TASK->lock);
                 spinlock_lock(&TASK->answerbox.lock);
                 if (list_empty(&TASK->answerbox.connected_phones)) {
                     /* Last phone has been disconnected */
-                    TASK->kb_thread_at_hand = false;
                     TASK->kb_thread = NULL;
                     done = true;
-                    printf("phone list is empty\n");
+                    klog_printf("phone list is empty");
+                }
                 spinlock_unlock(&TASK->answerbox.lock);
                 spinlock_unlock(&TASK->lock);
                 interrupts_restore(ipl);
+            }
+        }
+    }
+    klog_printf("kbox: done, waking up possible shutdown routine");
+    waitq_wakeup(&TASK->kb_thread_shutdown_wq, WAKEUP_ALL);
     klog_printf("kbox: finished");
+}
 /**
  * Connect phone to a task kernel-box specified by id.
+ *
+ * Note that this is not completely atomic. For optimisation reasons,
+ * The task might start cleaning up kbox after the phone has been connected
+ * and before a kbox thread has been created. This must be taken into account
+ * in the cleanup code.
+ *
  * @return      Phone id on success, or negative error code.
  */
 int ipc_connect_kbox(task_id_t taskid)
+{
     int newphid;
     task_t *ta;
     thread_t *kb_thread;
-    int rc;
     ipl_t ipl;
+    bool had_kb_thread;
     newphid = phone_alloc();
     if (newphid < 0)
         return ELIMIT;
     spinlock_lock(&tasks_lock);
     ta = task_find_by_id(taskid);
     if (ta == NULL) {
         spinlock_unlock(&tasks_lock);
+        interrupts_restore(ipl);
         return ENOENT;
+    }
-    spinlock_lock(&ta->lock);
+    spinlock_lock(&ta->kb_cleanup_lock);
     spinlock_unlock(&tasks_lock);
+    /*
+     * Only ta->kb_cleanup_lock left. Since we checked the value
+     * of ta->kb_finished, this suffices to ensure the task's exitence.
+     * (And that it didn't start kbox cleanup yet). It also ensures
-    ipc_phone_connect(&TASK->phones[newphid], &ta->kernel_box);
+     * mutual exclusion with other threads running this function.
+     */
-    if (ta->kb_thread_at_hand == false) {
+    if (ta->kb_finished != false) {
-        ta->kb_thread_at_hand = true;
-        spinlock_unlock(&ta->lock);
+        spinlock_unlock(&ta->kb_cleanup_lock);
         interrupts_restore(ipl);
+        return EINVAL;
+    }
-        kb_thread = thread_create(kbox_thread_proc,
+    /* Connect the newly allocated phone to the kbox */
-            NULL, ta, THREAD_FLAG_NOATTACH, "kbox", false);
+    ipc_phone_connect(&TASK->phones[newphid], &ta->kernel_box);
-        if (!kb_thread)
-            return ENOMEM;
-        rc = thread_attach_by_id(kb_thread, taskid);
+    had_kb_thread = (ta->kb_thread != NULL);
+    /*
+     * Release all locks. This is an optimisation, that makes
+     * unnecessary thread creation very unlikely.
+     */
-        if (rc == EOK) {
+    spinlock_unlock(&ta->kb_cleanup_lock);
-            ipl = interrupts_disable();
+    interrupts_restore(ipl);
-            spinlock_lock(&ta->lock);
+    /* Create a kbox thread */
-            ta->kb_thread = kb_thread;
+    kb_thread = thread_create(kbox_thread_proc,
+        NULL, ta, THREAD_FLAG_NOATTACH, "kbox", false);
-            spinlock_unlock(&ta->lock);
+    if (!kb_thread)
+        return ENOMEM;
+    /*
+     * It might happen that someone else has attached a kbox thread.
+     * in the meantime. Also, the task might have gone or shut down.
-            interrupts_restore(ipl);
+     * Let's try from the beginning.
+     */
-            thread_detach(kb_thread);
+    ipl = interrupts_disable();
-            thread_ready(kb_thread);
+    spinlock_lock(&tasks_lock);
-        } else {
-            /* Return the allocated thread struct */
-            thread_unattached_free(kb_thread);
+    ta = task_find_by_id(taskid);
-        }
-    } else {
+    if (ta == NULL) {
-        spinlock_unlock(&ta->lock);
+        spinlock_unlock(&tasks_lock);
-        interrupts_restore(ipl);
+        return ENOENT;
+    }
+    spinlock_lock(&ta->kb_cleanup_lock);
+    spinlock_unlock(&tasks_lock);
+    if (ta->kb_finished != false || ta->kb_thread != NULL) {
+        spinlock_unlock(&ta->kb_cleanup_lock);
+        interrupts_restore(ipl);
+        /*
+         * Release the allocated thread struct. This won't
+         * happen too often, only if two CPUs raced for
+         * connecting to the kbox.
+         */
+        thread_unattached_free(kb_thread);
+        return EINVAL;
+    }
+    /* Attach thread */
+    ta->kb_thread = kb_thread;
+    thread_attach(kb_thread, ta);
+    thread_detach(kb_thread);
+    thread_ready(kb_thread);
+    spinlock_unlock(&ta->kb_cleanup_lock);
+    interrupts_restore(ipl);
     return newphid;
+}
 /** @}
  */

Subversion Repositories HelenOS

(root)//branches/tracing/kernel/generic/src/ipc/ipc.c – Rev 2870 → 2902