Changeset 43e2cbc in mainline for kernel/generic/src/ipc/sysipc.c

Timestamp:

2016-09-10T13:56:43Z (9 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

0b00599

Parents:

838ea8aa

Message:

Implement interruptible wait for messages sent by the kernel

This pertains specifically to handling the IPC_M_PAGE_IN requests
sent by the kernel on behalf of the faulting thread. If the external
pager process does not respond for some reason, the user may decide to
kill the blocked client. That will result in interrupting the client
from the sleep. The kernel will then perform cleanup.

This changeset implements the cleanup by either forgetting the call
(i.e. donating it to the callee) or waiting for the arriving answer,
whichever of the two succeeds.

File:

• kernel/generic/src/ipc/sysipc.c (modified) (2 diffs)

kernel/generic/src/ipc/sysipc.c

@@ -285 +285 @@
 #endif
 
-                rc = ipc_call_sync(phone, call); 
+                ipc_call_hold(call);
+                rc = ipc_call_sync(phone, call);
+                spinlock_lock(&call->forget_lock);
+                bool forgotten = call->forget;
+                spinlock_unlock(&call->forget_lock);
+                ipc_call_release(call);
 
 #ifdef CONFIG_UDEBUG
@@ -291 +296 @@
 #endif
 
-                if (rc != EOK)
-                        return EINTR;
+                if (rc != EOK) {
+                        if (!forgotten) {
+                                /*
+                                 * There was an error, but it did not result
+                                 * in the call being forgotten. In fact, the
+                                 * call was not even sent. We are still
+                                 * its owners and are responsible for its
+                                 * deallocation.
+                                 */
+                                ipc_call_free(call);
+                        } else {
+                                /*
+                                 * The call was forgotten and it changed hands.
+                                 * We are no longer expected to free it.
+                                 */
+                                ASSERT(rc == EINTR);
+                        }
+                        return rc;      
+                }
 
                 process_answer(call);