Changeset 8a18d5b in mainline for uspace/lib/c/generic/thread/futex.c

Timestamp:

2018-11-11T15:47:39Z (5 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

269bc459

Parents:

0b5203b

git-author:

Jakub Jermar <jakub@…> (2018-11-10 16:22:29)

git-committer:

Jakub Jermar <jakub@…> (2018-11-11 15:47:39)

Message:

Preallocate the waitq handle

This fixes a race condition (a missing wakeup) when the wakeup was
faster than the thread going to sleep and no handle was allocated yet.
The handle get preallocated to avoid a possible allocation failure in
wakeup.

We also switched to using atomic_compare_exchange_weak_explicit() to fix
ARMv4 and ARMv5 builds.

File:

• uspace/lib/c/generic/thread/futex.c (modified) (1 diff)

uspace/lib/c/generic/thread/futex.c

@@ -53 +53 @@
 {
         atomic_store_explicit(&futex->val, val, memory_order_relaxed);
-        atomic_store_explicit(&futex->alloc_lock, 0, memory_order_relaxed);
+        atomic_store_explicit(&futex->lock, 0, memory_order_relaxed);
         futex->whandle = CAP_NIL;
 }