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authorkolya <kolya>2008-10-15 05:01:39 +0000
committerkolya <kolya>2008-10-15 05:01:39 +0000
commit228e500a0c2b5a26492c84f73951a46c58c86509 (patch)
tree5be5a0fd9c9ad4b60d471e3fb5ff3d187512dc9f
parent15ce79de141f66c7dd2f2948ce4584a2d31f7040 (diff)
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save cpus.intena in sched(), so we get the right EFLAGS.IF value once a
timer-preempted kernel thread resumes execution in trap() after yield(). otherwise the kernel could get an arbitrary number of nested timer intrs.
-rw-r--r--proc.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/proc.c b/proc.c
index 614a130..fdd633d 100644
--- a/proc.c
+++ b/proc.c
@@ -207,7 +207,7 @@ scheduler(void)
c = &cpus[cpu()];
for(;;){
- // Enable interrupts on this processor.
+ // Enable interrupts on this processor, in lieu of saving intena.
sti();
// Loop over process table looking for process to run.
@@ -240,6 +240,8 @@ scheduler(void)
void
sched(void)
{
+ int intena;
+
if(read_eflags()&FL_IF)
panic("sched interruptible");
if(cp->state == RUNNING)
@@ -249,7 +251,9 @@ sched(void)
if(cpus[cpu()].ncli != 1)
panic("sched locks");
+ intena = cpus[cpu()].intena;
swtch(&cp->context, &cpus[cpu()].context);
+ cpus[cpu()].intena = intena;
}
// Give up the CPU for one scheduling round.