WebSVN – HelenOS – Diff – /trunk/kernel/generic/src/proc/task.c

 /*
  * Copyright (c) 2001-2004 Jakub Jermar
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /** @addtogroup genericproc
  * @{
  */
 /**
  * @file
  * @brief   Task management.
  */
 #include <main/uinit.h>
 #include <proc/thread.h>
 #include <proc/task.h>
 #include <proc/uarg.h>
 #include <mm/as.h>
 #include <mm/slab.h>
 #include <atomic.h>
 #include <synch/spinlock.h>
 #include <synch/waitq.h>
 #include <arch.h>
 #include <panic.h>
 #include <adt/btree.h>
 #include <adt/list.h>
 #include <ipc/ipc.h>
 #include <security/cap.h>
 #include <memstr.h>
 #include <print.h>
 #include <lib/elf.h>
 #include <errno.h>
 #include <func.h>
 #include <syscall/copy.h>
-#include <console/klog.h>
 #ifndef LOADED_PROG_STACK_PAGES_NO
 #define LOADED_PROG_STACK_PAGES_NO 1
 #endif
 /** Spinlock protecting the tasks_btree B+tree. */
 SPINLOCK_INITIALIZE(tasks_lock);
 /** B+tree of active tasks.
+ *
  * The task is guaranteed to exist after it was found in the tasks_btree as
  * long as:
  * @li the tasks_lock is held,
  * @li the task's lock is held when task's lock is acquired before releasing
  *     tasks_lock or
  * @li the task's refcount is greater than 0
+ *
  */
 btree_t tasks_btree;
 static task_id_t task_counter = 0;
-static void ktaskclnp(void *arg);
-static void ktaskgc(void *arg);
 /** Initialize tasks
+ *
  * Initialize kernel tasks support.
+ *
  */
 void task_init(void)
+{
     TASK = NULL;
     btree_create(&tasks_btree);
+}
 /** Kill all tasks except the current task.
+ *
  */
 void task_done(void)
+{
     task_t *t;
     do { /* Repeat until there are any tasks except TASK */
         /* Messing with task structures, avoid deadlock */
         ipl_t ipl = interrupts_disable();
         spinlock_lock(&tasks_lock);
         t = NULL;
         link_t *cur;
         for (cur = tasks_btree.leaf_head.next;
             cur != &tasks_btree.leaf_head; cur = cur->next) {
             btree_node_t *node;
             node = list_get_instance(cur, btree_node_t, leaf_link);
             unsigned int i;
             for (i = 0; i < node->keys; i++) {
                 if ((task_t *) node->value[i] != TASK) {
                     t = (task_t *) node->value[i];
                     break;
+                }
+            }
+        }
         if (t != NULL) {
             task_id_t id = t->taskid;
             spinlock_unlock(&tasks_lock);
             interrupts_restore(ipl);
 #ifdef CONFIG_DEBUG
             printf("Killing task %llu\n", id);
 #endif
             task_kill(id);
         } else {
             spinlock_unlock(&tasks_lock);
             interrupts_restore(ipl);
+        }
     } while (t != NULL);
+}
 /** Create new task
+ *
  * Create new task with no threads.
+ *
  * @param as Task's address space.
  * @param name Symbolic name.
+ *
  * @return New task's structure
+ *
  */
 task_t *task_create(as_t *as, char *name)
+{
     ipl_t ipl;
     task_t *ta;
     int i;
     ta = (task_t *) malloc(sizeof(task_t), 0);
     task_create_arch(ta);
     spinlock_initialize(&ta->lock, "task_ta_lock");
     list_initialize(&ta->th_head);
     ta->as = as;
     ta->name = name;
-    ta->main_thread = NULL;
+    atomic_set(&ta->refcount, 0);
-    ta->refcount = 0;
+    atomic_set(&ta->lifecount, 0);
     ta->context = CONTEXT;
     ta->capabilities = 0;
-    ta->accept_new_threads = true;
     ta->cycles = 0;
     ipc_answerbox_init(&ta->answerbox);
     for (i = 0; i < IPC_MAX_PHONES; i++)
         ipc_phone_init(&ta->phones[i]);
     if ((ipc_phone_0) && (context_check(ipc_phone_0->task->context,
         ta->context)))
         ipc_phone_connect(&ta->phones[0], ipc_phone_0);
     atomic_set(&ta->active_calls, 0);
     mutex_initialize(&ta->futexes_lock);
     btree_create(&ta->futexes);
     ipl = interrupts_disable();
     /*
      * Increment address space reference count.
      */
     atomic_inc(&as->refcount);
     spinlock_lock(&tasks_lock);
     ta->taskid = ++task_counter;
     btree_insert(&tasks_btree, (btree_key_t) ta->taskid, (void *) ta, NULL);
     spinlock_unlock(&tasks_lock);
     interrupts_restore(ipl);
     return ta;
+}
 /** Destroy task.
+ *
  * @param t Task to be destroyed.
  */
 void task_destroy(task_t *t)
+{
+    /*
+     * Remove the task from the task B+tree.
+     */
+    spinlock_lock(&tasks_lock);
+    btree_remove(&tasks_btree, t->taskid, NULL);
+    spinlock_unlock(&tasks_lock);
+    /*
+     * Perform architecture specific task destruction.
+     */
     task_destroy_arch(t);
+    /*
+     * Free up dynamically allocated state.
+     */
     btree_destroy(&t->futexes);
+    /*
+     * Drop our reference to the address space.
+     */
     if (atomic_predec(&t->as->refcount) == 0)
         as_destroy(t->as);
     free(t);
     TASK = NULL;
+}
 /** Create new task with 1 thread and run it
+ *
  * @param program_addr Address of program executable image.
  * @param name Program name.
+ *
  * @return Task of the running program or NULL on error.
  */
 task_t *task_run_program(void *program_addr, char *name)
+{
     as_t *as;
     as_area_t *a;
     int rc;
-    thread_t *t1, *t2;
+    thread_t *t;
     task_t *task;
     uspace_arg_t *kernel_uarg;
     as = as_create(0);
     ASSERT(as);
     rc = elf_load((elf_header_t *) program_addr, as);
     if (rc != EE_OK) {
         as_destroy(as);
         return NULL;
+    }
     kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);
     kernel_uarg->uspace_entry =
         (void *) ((elf_header_t *) program_addr)->e_entry;
     kernel_uarg->uspace_stack = (void *) USTACK_ADDRESS;
     kernel_uarg->uspace_thread_function = NULL;
     kernel_uarg->uspace_thread_arg = NULL;
     kernel_uarg->uspace_uarg = NULL;
     task = task_create(as, name);
     ASSERT(task);
     /*
      * Create the data as_area.
      */
     a = as_area_create(as, AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE,
         LOADED_PROG_STACK_PAGES_NO * PAGE_SIZE, USTACK_ADDRESS,
         AS_AREA_ATTR_NONE, &anon_backend, NULL);
     /*
      * Create the main thread.
      */
-    t1 = thread_create(uinit, kernel_uarg, task, THREAD_FLAG_USPACE,
+    t = thread_create(uinit, kernel_uarg, task, THREAD_FLAG_USPACE,
         "uinit", false);
-    ASSERT(t1);
+    ASSERT(t);
-    /*
-     * Create killer thread for the new task.
-     */
-    t2 = thread_create(ktaskgc, t1, task, 0, "ktaskgc", true);
-    ASSERT(t2);
-    thread_ready(t2);
+    thread_ready(t);
-    thread_ready(t1);
     return task;
+}
 /** Syscall for reading task ID from userspace.
+ *
  * @param uspace_task_id Userspace address of 8-byte buffer where to store
  * current task ID.
+ *
  * @return 0 on success or an error code from @ref errno.h.
  */
 unative_t sys_task_get_id(task_id_t *uspace_task_id)
+{
     /*
      * No need to acquire lock on TASK because taskid
      * remains constant for the lifespan of the task.
      */
     return (unative_t) copy_to_uspace(uspace_task_id, &TASK->taskid,
         sizeof(TASK->taskid));
+}
 /** Find task structure corresponding to task ID.
+ *
  * The tasks_lock must be already held by the caller of this function
  * and interrupts must be disabled.
+ *
  * @param id Task ID.
+ *
  * @return Task structure address or NULL if there is no such task ID.
  */
 task_t *task_find_by_id(task_id_t id)
+{
     btree_node_t *leaf;
     return (task_t *) btree_search(&tasks_btree, (btree_key_t) id, &leaf);
+}
 /** Get accounting data of given task.
+ *
  * Note that task lock of 't' must be already held and
  * interrupts must be already disabled.
+ *
  * @param t Pointer to thread.
+ *
  */
 uint64_t task_get_accounting(task_t *t)
+{
     /* Accumulated value of task */
     uint64_t ret = t->cycles;
     /* Current values of threads */
     link_t *cur;
     for (cur = t->th_head.next; cur != &t->th_head; cur = cur->next) {
         thread_t *thr = list_get_instance(cur, thread_t, th_link);
         spinlock_lock(&thr->lock);
         /* Process only counted threads */
         if (!thr->uncounted) {
             if (thr == THREAD) {
                 /* Update accounting of current thread */
                 thread_update_accounting();
+            }
             ret += thr->cycles;
+        }
         spinlock_unlock(&thr->lock);
+    }
     return ret;
+}
 /** Kill task.
+ *
+ * This function is idempotent.
+ * It signals all the task's threads to bail it out.
+ *
  * @param id ID of the task to be killed.
+ *
  * @return 0 on success or an error code from errno.h
  */
 int task_kill(task_id_t id)
+{
     ipl_t ipl;
     task_t *ta;
-    thread_t *t;
     link_t *cur;
     if (id == 1)
         return EPERM;
     ipl = interrupts_disable();
     spinlock_lock(&tasks_lock);
     if (!(ta = task_find_by_id(id))) {
         spinlock_unlock(&tasks_lock);
         interrupts_restore(ipl);
         return ENOENT;
+    }
-    spinlock_lock(&ta->lock);
-    ta->refcount++;
-    spinlock_unlock(&ta->lock);
-    btree_remove(&tasks_btree, ta->taskid, NULL);
     spinlock_unlock(&tasks_lock);
-    t = thread_create(ktaskclnp, NULL, ta, 0, "ktaskclnp", true);
-    spinlock_lock(&ta->lock);
-    ta->accept_new_threads = false;
-    ta->refcount--;
     /*
      * Interrupt all threads except ktaskclnp.
      */
+    spinlock_lock(&ta->lock);
     for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {
         thread_t *thr;
-        bool  sleeping = false;
+        bool sleeping = false;
         thr = list_get_instance(cur, thread_t, th_link);
-        if (thr == t)
-            continue;
         spinlock_lock(&thr->lock);
         thr->interrupted = true;
         if (thr->state == Sleeping)
             sleeping = true;
         spinlock_unlock(&thr->lock);
         if (sleeping)
             waitq_interrupt_sleep(thr);
+    }
     spinlock_unlock(&ta->lock);
     interrupts_restore(ipl);
-    if (t)
-        thread_ready(t);
     return 0;
+}
 /** Print task list */
 void task_print_list(void)
+{
     link_t *cur;
     ipl_t ipl;
     /* Messing with task structures, avoid deadlock */
     ipl = interrupts_disable();
     spinlock_lock(&tasks_lock);
     printf("taskid name       ctx address    as         cycles     threads "
         "calls  callee\n");
-    printf("------ ---------- --- ---------- ---------- ---------- ------- "        "------ ------>\n");
+    printf("------ ---------- --- ---------- ---------- ---------- ------- "
+        "------ ------>\n");
     for (cur = tasks_btree.leaf_head.next; cur != &tasks_btree.leaf_head;
         cur = cur->next) {
         btree_node_t *node;
         unsigned int i;
         node = list_get_instance(cur, btree_node_t, leaf_link);
         for (i = 0; i < node->keys; i++) {
             task_t *t;
             int j;
             t = (task_t *) node->value[i];
             spinlock_lock(&t->lock);
             uint64_t cycles;
             char suffix;
             order(task_get_accounting(t), &cycles, &suffix);
             printf("%-6llu %-10s %-3ld %#10zx %#10zx %9llu%c %7zd "
                 "%6zd", t->taskid, t->name, t->context, t, t->as,
                 cycles, suffix, t->refcount,
                 atomic_get(&t->active_calls));
             for (j = 0; j < IPC_MAX_PHONES; j++) {
                 if (t->phones[j].callee)
                     printf(" %zd:%#zx", j,
                         t->phones[j].callee);
+            }
             printf("\n");
             spinlock_unlock(&t->lock);
+        }
+    }
     spinlock_unlock(&tasks_lock);
     interrupts_restore(ipl);
+}
-/** Kernel thread used to cleanup the task after it is killed. */
-void ktaskclnp(void *arg)
-{
-    ipl_t ipl;
-    thread_t *t = NULL, *main_thread;
-    link_t *cur;
-    bool again;
-    thread_detach(THREAD);
-loop:
-    ipl = interrupts_disable();
-    spinlock_lock(&TASK->lock);
-    main_thread = TASK->main_thread;
-    /*
-     * Find a thread to join.
-     */
-    again = false;
-    for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
-        t = list_get_instance(cur, thread_t, th_link);
-        spinlock_lock(&t->lock);
-        if (t == THREAD) {
-            spinlock_unlock(&t->lock);
-            continue;
-        } else if (t == main_thread) {
-            spinlock_unlock(&t->lock);
-            continue;
-        } else if (t->join_type != None) {
-            spinlock_unlock(&t->lock);
-            again = true;
-            continue;
-        } else {
-            t->join_type = TaskClnp;
-            spinlock_unlock(&t->lock);
-            again = false;
-            break;
-        }
-    }
-    spinlock_unlock(&TASK->lock);
-    interrupts_restore(ipl);
-    if (again) {
-        /*
-         * Other cleanup (e.g. ktaskgc) is in progress.
-         */
-        scheduler();
-        goto loop;
-    }
-    if (t != THREAD) {
-        ASSERT(t != main_thread);   /* uninit is joined and detached
-                         * in ktaskgc */
-        thread_join(t);
-        thread_detach(t);
-        goto loop;          /* go for another thread */
-    }
-    /*
-     * Now there are no other threads in this task
-     * and no new threads can be created.
-     */
-    ipc_cleanup();
-    futex_cleanup();
-    klog_printf("Cleanup of task %llu completed.", TASK->taskid);
-}
-/** Kernel thread used to kill the userspace task when its main thread exits.
- *
- * This thread waits until the main userspace thread (i.e. uninit) exits.
- * When this happens, the task is killed. In the meantime, exited threads
- * are garbage collected.
- *
- * @param arg Pointer to the thread structure of the task's main thread.
- */
-void ktaskgc(void *arg)
-{
-    thread_t *t = (thread_t *) arg;
-loop:
-    /*
-     * Userspace threads cannot detach themselves,
-     * therefore the thread pointer is guaranteed to be valid.
-     */
-    if (thread_join_timeout(t, 1000000, SYNCH_FLAGS_NONE) ==
-        ESYNCH_TIMEOUT) {   /* sleep uninterruptibly here! */
-        ipl_t ipl;
-        link_t *cur;
-        thread_t *thr = NULL;
-        /*
-         * The join timed out. Try to do some garbage collection of
-         * Undead threads.
-         */
-more_gc:
-        ipl = interrupts_disable();
-        spinlock_lock(&TASK->lock);
-        for (cur = TASK->th_head.next; cur != &TASK->th_head;
-            cur = cur->next) {
-            thr = list_get_instance(cur, thread_t, th_link);
-            spinlock_lock(&thr->lock);
-            if (thr != t && thr->state == Undead &&
-                thr->join_type == None) {
-                thr->join_type = TaskGC;
-                spinlock_unlock(&thr->lock);
-                break;
-            }
-            spinlock_unlock(&thr->lock);
-            thr = NULL;
-        }
-        spinlock_unlock(&TASK->lock);
-        interrupts_restore(ipl);
-        if (thr) {
-            thread_join(thr);
-            thread_detach(thr);
-            scheduler();
-            goto more_gc;
-        }
-        goto loop;
-    }
-    thread_detach(t);
-    task_kill(TASK->taskid);
-}
 /** @}
  */

Subversion Repositories HelenOS

(root)/trunk/kernel/generic/src/proc/task.c – Rev 2436 → 2446