Changeset 9f2f5ee in mainline for kernel/generic/include/synch/mutex.h

Timestamp:

2025-04-10T17:48:56Z (5 days ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master

Children:

c55ab66

Parents:

c626117

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2025-04-10 10:55:54)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2025-04-10 17:48:56)

Message:

Rewrite kernel mutex implementation a little

Removes MUTEX_ACTIVE, the use of which has been removed in favor of
irq_spinlock_t, and fixes some issues with the old implementation.

• A race in mtx→owner access is unavoidable, so make it explicitly atomic.
• The THREAD==NULL case happens when there are no other threads yet, so we factor it out as a special case. Also ensures recursive mutex works before threads are initialized, just as normal mutex does.
• More and better asserts.

File:

• kernel/generic/include/synch/mutex.h (modified) (2 diffs)

kernel/generic/include/synch/mutex.h

@@ -44 +44 @@
         MUTEX_PASSIVE,
         MUTEX_RECURSIVE,
-        MUTEX_ACTIVE
 } mutex_type_t;
 
@@ -51 +50 @@
 typedef struct {
         mutex_type_t type;
+        int nesting;
         semaphore_t sem;
-        struct thread *owner;
-        unsigned nesting;
+        _Atomic(struct thread *) owner;
 } mutex_t;
 
 #define MUTEX_INITIALIZER(name, mtype) (mutex_t) { \
         .type = (mtype), \
+        .nesting = 0, \
         .sem = SEMAPHORE_INITIALIZER((name).sem, 1), \
         .owner = NULL, \
-        .nesting = 0, \
 }