Changeset 7e58979 in mainline for kernel/arch/ia32/src/smp/apic.c

Timestamp:

2007-04-07T22:30:01Z (18 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

7bcfbbc

Parents:

201abde

Message:

On SMP amd64 and ia32 systems, release the irq→lock
before calling clock() from the interrupt handler.
This is important for maintaining kernel preemption
since no preemption can take place while a spinlock
is held.

File:

• kernel/arch/ia32/src/smp/apic.c (modified) (1 diff)

kernel/arch/ia32/src/smp/apic.c

@@ -140 +140 @@
 static void l_apic_timer_irq_handler(irq_t *irq, void *arg, ...)
 {
+        /*
+         * Holding a spinlock could prevent clock() from preempting
+         * the current thread. In this case, we don't need to hold the
+         * irq->lock so we just unlock it and then lock it again.
+         */
+        spinlock_unlock(&irq->lock);
         clock();
+        spinlock_lock(&irq->lock);
 }