xv6

Unnamed repository; edit this file 'description' to name the repository.
Log | Files | Refs | README | LICENSE

commit 228e500a0c2b5a26492c84f73951a46c58c86509
parent 15ce79de141f66c7dd2f2948ce4584a2d31f7040
Author: kolya <kolya>
Date:   Wed, 15 Oct 2008 05:01:39 +0000

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.

Diffstat:
Mproc.c | 6+++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git 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.