Changeset 96c30c8 in mainline for kernel/generic/src/ipc/ipc.c

Timestamp:

2018-06-28T15:45:37Z (7 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Branches:

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

Children:

331d024

Parents:

82453b29

git-author:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-06-28 15:36:29)

git-committer:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-06-28 15:45:37)

Message:

Turn ipc_poke() into a regular wakeup on the waitq.

With prior behavior of ignoring the poke when no thread is blocking,
a thread could go to sleep just after a poke meant for it and sleep
indefinitely despite there being work to do.

After the change, worst case scenario, thread enters ipc wait, exits
immediately due to a previous poke, finds no work to do and enters ipc wait
again (possibly repeating the spurious wakeup a few times).

File:

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

kernel/generic/src/ipc/ipc.c

@@ -550 +550 @@
         errno_t rc;
 
-restart:
         rc = waitq_sleep_timeout(&box->wq, usec, flags, NULL);
         if (rc != EOK)
@@ -590 +589 @@
                 list_append(&request->ab_link, &box->dispatched_calls);
         } else {
-                /* This can happen regularly after ipc_cleanup */
+                /*
+                 * This can happen regularly after ipc_cleanup, or in
+                 * response to ipc_poke(). Let the caller sort out the wakeup.
+                 */
                 irq_spinlock_unlock(&box->lock, true);
-                goto restart;
+                return NULL;
         }