Changeset ba25c4b in mainline

Timestamp:

2023-02-09T15:31:39Z (2 years ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

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

Children:

83789ea2

Parents:

78acbc72

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2023-02-09 15:28:13)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2023-02-09 15:31:39)

Message:

Synchronize timeout_unregister() with handler execution

This ensures that when timeout_unregister() returns,
timeout handler either didn't run at all, or it ran to
completion and is no longer executing.

This will be handy a few patches later.

Location:

kernel/generic

Files:

• include/time/timeout.h (modified) (1 diff)
• src/time/clock.c (modified) (1 diff)
• src/time/timeout.c (modified) (2 diffs)

kernel/generic/include/time/timeout.h

@@ -53 +53 @@
         /** On which processor is this timeout registered. */
         cpu_t *cpu;
+        /** Used to synchronize with the handler callback. */
+        atomic_bool finished;
 } timeout_t;
 

kernel/generic/src/time/clock.c

@@ -168 +168 @@
                 timeout_handler_t handler = timeout->handler;
                 void *arg = timeout->arg;
+                atomic_bool *finished = &timeout->finished;
 
                 irq_spinlock_unlock(&CPU->timeoutlock, false);
 
                 handler(arg);
+
+                /* Signal that the handler is finished. */
+                atomic_store_explicit(finished, true, memory_order_release);
 
                 irq_spinlock_lock(&CPU->timeoutlock, false);

kernel/generic/src/time/timeout.c

@@ -90 +90 @@
         assert(!link_in_use(&timeout->link));
 
-        timeout->cpu = CPU;
-        timeout->deadline = CPU->current_clock_tick + us2ticks(time);
-        timeout->handler = handler;
-        timeout->arg = arg;
+        *timeout = (timeout_t) {
+                .cpu = CPU,
+                .deadline = CPU->current_clock_tick + us2ticks(time),
+                .handler = handler,
+                .arg = arg,
+                .finished = ATOMIC_VAR_INIT(false),
+        };
 
         /* Insert timeout into the active timeouts list according to timeout->deadline. */
@@ -135 +138 @@
 
         irq_spinlock_unlock(&timeout->cpu->timeoutlock, true);
+
+        if (!success) {
+                /* Timeout was fired, we need to wait for the callback to finish. */
+                while (!atomic_load_explicit(&timeout->finished, memory_order_acquire))
+                        cpu_spin_hint();
+        }
+
         return success;
 }