Changeset 50dd854 in mainline

Timestamp:

2018-03-13T18:01:48Z (6 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

334c103

Parents:

1b4196d

git-author:

Jakub Jermar <jakub@…> (2018-03-10 17:56:32)

git-committer:

Jakub Jermar <jakub@…> (2018-03-13 18:01:48)

Message:

Publish capability only after phone connects

In IPC_M_CONNECT_ME_TO it is desirable to publish the new phone
capability only after the phone gets connected. Otherwise we might have
open phones without capabilities and no way to hang them up in
ipc_cleanup().

File:

• kernel/generic/src/ipc/ops/conctmeto.c (modified) (5 diffs)

kernel/generic/src/ipc/ops/conctmeto.c

@@ -44 +44 @@
         cap_handle_t phone_handle;
         errno_t rc = phone_alloc(TASK, &phone_handle);
-
-        /* Remember the phone capability or that an error occured. */
-        call->priv = (rc == EOK) ? phone_handle : -1;
-
         if (rc != EOK) {
+                call->priv = -1;
                 return rc;
         }
 
-        /* Set ARG5 for server */
-        kobject_t *phone_obj = kobject_get(TASK, phone_handle,
+        /*
+         * The capability is now published, but the phone is not connected yet.
+         * The user cannot use it to send anything over it, in fact the
+         * userspace can only unpublish and free the capability at this point.
+         *
+         * We now proceed to test the capability is still there. We don't care
+         * if the user destroyed the old one and recreated a new published one
+         * of the same type under the same handle.
+         *
+         * If the capability is in place we temporarily unpublish it to make
+         * sure the user cannot fiddle with it while we are connecting.
+         */
+
+        kobject_t *phone_obj = cap_unpublish(TASK, phone_handle,
             KOBJECT_TYPE_PHONE);
         if (!phone_obj) {
@@ -63 +72 @@
                 return ENOENT;
         }
+
         /* Hand over phone_obj's reference to ARG5 */
         IPC_SET_ARG5(call->data, (sysarg_t) phone_obj->phone);
+
+        /* Remember the handle */
+        call->priv = phone_handle;
 
         return EOK;
@@ -73 +86 @@
         cap_handle_t phone_handle = (cap_handle_t) call->priv;
 
-        if (phone_handle < 0) {
+        if (phone_handle < 0)
                 return EOK;
-        }
 
-        phone_dealloc(phone_handle);
         /* Hand over reference from ARG5 to phone->kobject */
         phone_t *phone = (phone_t *) IPC_GET_ARG5(call->data);
-        /* Drop phone_obj's reference */
+        /* Drop phone->kobject's reference */
         kobject_put(phone->kobject);
+        cap_free(TASK, phone_handle);
+
         return EOK;
 }
@@ -90 +103 @@
         phone_t *phone = (phone_t *) IPC_GET_ARG5(*olddata);
 
-        /* If the user accepted call, connect */
+        /*
+         * Get an extra reference and pass it in the answer data.
+         */
+        kobject_add_ref(phone->kobject);
+        IPC_SET_ARG5(answer->data, (sysarg_t) phone);
+
+        /* If the user accepted the call, connect */
         if (IPC_GET_RETVAL(answer->data) == EOK) {
                 /* Hand over reference from phone to the answerbox */
@@ -104 +123 @@
 {
         cap_handle_t phone_handle = (cap_handle_t) answer->priv;
+        phone_t *phone = (phone_t *) IPC_GET_ARG5(answer->data);
 
         if (IPC_GET_RETVAL(answer->data)) {
                 if (phone_handle >= 0) {
                         /*
-                         * The phone was indeed allocated and now needs
-                         * to be deallocated.
+                         * Cleanup the unpublished capability and drop
+                         * phone->kobject's reference.
                          */
-                        phone_dealloc(phone_handle);
+                        kobject_put(phone->kobject);
+                        cap_free(TASK, phone_handle);
                 }
         } else {
+                /*
+                 * Publish the capability. Publishing the capability this late
+                 * is important for ipc_cleanup() where we want to have a
+                 * capability for each phone that wasn't hung up by the user.
+                 */
+                cap_publish(TASK, phone_handle, phone->kobject);
+
                 IPC_SET_ARG5(answer->data, phone_handle);
         }