+/*
+ * Routine: ipc_port_impcount_delta
+ * Purpose:
+ * Adjust only the importance count associated with a port.
+ * If there are any adjustments to be made to receiver task,
+ * those are handled elsewhere.
+ *
+ * For now, be defensive during deductions to make sure the
+ * impcount for the port doesn't underflow zero. This will
+ * go away when the port boost addition is made atomic (see
+ * note in ipc_port_importance_delta()).
+ * Conditions:
+ * The port is referenced and locked.
+ * Nothing else is locked.
+ */
+mach_port_delta_t
+ipc_port_impcount_delta(
+ ipc_port_t port,
+ mach_port_delta_t delta,
+ ipc_port_t __unused base)
+{
+ mach_port_delta_t absdelta;
+
+ if (!ip_active(port)) {
+ return 0;
+ }
+
+ /* adding/doing nothing is easy */
+ if (delta >= 0) {
+ port->ip_impcount += delta;
+ return delta;
+ }
+
+ absdelta = 0 - delta;
+ if (port->ip_impcount >= absdelta) {
+ port->ip_impcount -= absdelta;
+ return delta;
+ }
+
+#if (DEVELOPMENT || DEBUG)
+ if (port->ip_receiver_name != MACH_PORT_NULL) {
+ task_t target_task = port->ip_receiver->is_task;
+ ipc_importance_task_t target_imp = target_task->task_imp_base;
+ const char *target_procname;
+ int target_pid;
+
+ if (target_imp != IIT_NULL) {
+ target_procname = target_imp->iit_procname;
+ target_pid = target_imp->iit_bsd_pid;
+ } else {
+ target_procname = "unknown";
+ target_pid = -1;
+ }
+ printf("Over-release of importance assertions for port 0x%x receiver pid %d (%s), "
+ "dropping %d assertion(s) but port only has %d remaining.\n",
+ port->ip_receiver_name,
+ target_pid, target_procname,
+ absdelta, port->ip_impcount);
+
+ } else if (base != IP_NULL) {
+ task_t target_task = base->ip_receiver->is_task;
+ ipc_importance_task_t target_imp = target_task->task_imp_base;
+ const char *target_procname;
+ int target_pid;
+
+ if (target_imp != IIT_NULL) {
+ target_procname = target_imp->iit_procname;
+ target_pid = target_imp->iit_bsd_pid;
+ } else {
+ target_procname = "unknown";
+ target_pid = -1;
+ }
+ printf("Over-release of importance assertions for port 0x%lx "
+ "enqueued on port 0x%x with receiver pid %d (%s), "
+ "dropping %d assertion(s) but port only has %d remaining.\n",
+ (unsigned long)VM_KERNEL_UNSLIDE_OR_PERM((uintptr_t)port),
+ base->ip_receiver_name,
+ target_pid, target_procname,
+ absdelta, port->ip_impcount);
+ }
+#endif
+
+ delta = 0 - port->ip_impcount;
+ port->ip_impcount = 0;
+ return delta;
+}
+
+/*
+ * Routine: ipc_port_importance_delta_internal
+ * Purpose:
+ * Adjust the importance count through the given port.
+ * If the port is in transit, apply the delta throughout
+ * the chain. Determine if the there is a task at the
+ * base of the chain that wants/needs to be adjusted,
+ * and if so, apply the delta.
+ * Conditions:
+ * The port is referenced and locked on entry.
+ * Importance may be locked.
+ * Nothing else is locked.
+ * The lock may be dropped on exit.
+ * Returns TRUE if lock was dropped.
+ */
+#if IMPORTANCE_INHERITANCE
+
+boolean_t
+ipc_port_importance_delta_internal(
+ ipc_port_t port,
+ natural_t options,
+ mach_port_delta_t *deltap,
+ ipc_importance_task_t *imp_task)
+{
+ ipc_port_t next, base;
+ boolean_t dropped = FALSE;
+
+ *imp_task = IIT_NULL;
+
+ if (*deltap == 0)
+ return FALSE;
+
+ assert(options == IPID_OPTION_NORMAL || options == IPID_OPTION_SENDPOSSIBLE);
+
+ base = port;
+
+ /* if port is in transit, have to search for end of chain */
+ if (ip_active(port) &&
+ port->ip_destination != IP_NULL &&
+ port->ip_receiver_name == MACH_PORT_NULL) {
+
+ dropped = TRUE;
+
+ ip_unlock(port);
+ ipc_port_multiple_lock(); /* massive serialization */
+ ip_lock(base);
+
+ while(ip_active(base) &&
+ base->ip_destination != IP_NULL &&
+ base->ip_receiver_name == MACH_PORT_NULL) {
+
+ base = base->ip_destination;
+ ip_lock(base);
+ }
+ ipc_port_multiple_unlock();
+ }
+
+ /*
+ * If the port lock is dropped b/c the port is in transit, there is a
+ * race window where another thread can drain messages and/or fire a
+ * send possible notification before we get here.
+ *
+ * We solve this race by checking to see if our caller armed the send
+ * possible notification, whether or not it's been fired yet, and
+ * whether or not we've already set the port's ip_spimportant bit. If
+ * we don't need a send-possible boost, then we'll just apply a
+ * harmless 0-boost to the port.
+ */
+ if (options & IPID_OPTION_SENDPOSSIBLE) {
+ assert(*deltap == 1);
+ if (port->ip_sprequests && port->ip_spimportant == 0)
+ port->ip_spimportant = 1;
+ else
+ *deltap = 0;
+ }
+
+ /* unlock down to the base, adjusting boost(s) at each level */
+ for (;;) {
+ *deltap = ipc_port_impcount_delta(port, *deltap, base);
+
+ if (port == base) {
+ break;
+ }
+
+ /* port is in transit */
+ assert(port->ip_tempowner == 0);
+ next = port->ip_destination;
+ ip_unlock(port);
+ port = next;
+ }
+
+ /* find the task (if any) to boost according to the base */
+ if (ip_active(base)) {
+ if (base->ip_tempowner != 0) {
+ if (IIT_NULL != base->ip_imp_task)
+ *imp_task = base->ip_imp_task;
+ /* otherwise don't boost */
+
+ } else if (base->ip_receiver_name != MACH_PORT_NULL) {
+ ipc_space_t space = base->ip_receiver;
+
+ /* only spaces with boost-accepting tasks */
+ if (space->is_task != TASK_NULL &&
+ ipc_importance_task_is_any_receiver_type(space->is_task->task_imp_base)) {
+ *imp_task = space->is_task->task_imp_base;
+ }
+ }
+ }
+
+ /*
+ * Only the base is locked. If we have to hold or drop task
+ * importance assertions, we'll have to drop that lock as well.
+ */
+ if (*imp_task != IIT_NULL) {
+ /* take a reference before unlocking base */
+ ipc_importance_task_reference(*imp_task);
+ }
+
+ if (dropped == TRUE) {
+ ip_unlock(base);
+ }
+
+ return dropped;
+}
+#endif /* IMPORTANCE_INHERITANCE */
+
+/*
+ * Routine: ipc_port_importance_delta
+ * Purpose:
+ * Adjust the importance count through the given port.
+ * If the port is in transit, apply the delta throughout
+ * the chain.
+ *
+ * If there is a task at the base of the chain that wants/needs
+ * to be adjusted, apply the delta.
+ * Conditions:
+ * The port is referenced and locked on entry.
+ * Nothing else is locked.
+ * The lock may be dropped on exit.
+ * Returns TRUE if lock was dropped.
+ */
+#if IMPORTANCE_INHERITANCE
+
+boolean_t
+ipc_port_importance_delta(
+ ipc_port_t port,
+ natural_t options,
+ mach_port_delta_t delta)
+{
+ ipc_importance_task_t imp_task = IIT_NULL;
+ boolean_t dropped;
+
+ dropped = ipc_port_importance_delta_internal(port, options, &delta, &imp_task);
+
+ if (IIT_NULL == imp_task || delta == 0)
+ return dropped;
+
+ if (!dropped)
+ ip_unlock(port);
+
+ assert(ipc_importance_task_is_any_receiver_type(imp_task));
+
+ if (delta > 0)
+ ipc_importance_task_hold_internal_assertion(imp_task, delta);
+ else
+ ipc_importance_task_drop_internal_assertion(imp_task, -delta);
+
+ ipc_importance_task_release(imp_task);
+ return TRUE;
+}
+#endif /* IMPORTANCE_INHERITANCE */
+
projects / apple / xnu.git / blobdiff