Changeset efed95a3 in mainline for kernel/generic/include

Timestamp:

2024-01-20T17:09:00Z (2 years ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master

Children:

3d84734

Parents:

286da52

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2024-01-20 16:12:46)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2024-01-20 17:09:00)

Message:

Make thread→cpu weakly atomic, to avoid need for thread lock

Location:

kernel/generic/include

Files:

• atomic.h (modified) (1 diff)
• proc/thread.h (modified) (1 diff)

kernel/generic/include/atomic.h

@@ -39 +39 @@
 #include <typedefs.h>
 #include <stdatomic.h>
+
+/*
+ * Shorthand for relaxed atomic read/write, something that's needed to formally
+ * avoid undefined behavior in cases where we need to read a variable in
+ * different threads and we don't particularly care about ordering
+ * (e.g. statistic printouts). This is most likely translated into the same
+ * assembly instructions as regular read/writes.
+ */
+#define atomic_set_unordered(var, val) atomic_store_explicit((var), (val), memory_order_relaxed)
+#define atomic_get_unordered(var) atomic_load_explicit((var), memory_order_relaxed)
 
 #define atomic_predec(val) \

kernel/generic/include/proc/thread.h

@@ -138 +138 @@
 
         /** Thread CPU. */
-        cpu_t *cpu;
+        _Atomic(cpu_t *) cpu;
         /** Containing task. */
         task_t *task;