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sched: move panic handling code out of choosethread

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This avoids jumps in the common case of the kernel not being panicked.
This commit is contained in:
Mateusz Guzik 2017-11-17 02:45:38 +00:00
parent 997131646f
commit 32aef9ff05
1 changed files with 20 additions and 7 deletions
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27
sys/kern/kern_switch.c
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@ -150,22 +150,21 @@ SYSCTL_PROC(_kern_sched_stats, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_WR, NULL,
/*
* Select the thread that will be run next.
*/
struct thread *
choosethread(void)
{
struct thread *td;
retry:
td = sched_choose();
static __noinline struct thread *
choosethread_panic(struct thread *td)
{
/*
* If we are in panic, only allow system threads,
* plus the one we are running in, to be run.
*/
if (panicstr && ((td->td_proc->p_flag & P_SYSTEM) == 0 &&
retry:
if (((td->td_proc->p_flag & P_SYSTEM) == 0 &&
(td->td_flags & TDF_INPANIC) == 0)) {
/* note that it is no longer on the run queue */
TD_SET_CAN_RUN(td);
td = sched_choose();
goto retry;
}
@ -173,6 +172,20 @@ retry:
return (td);
}
struct thread *
choosethread(void)
{
struct thread *td;
td = sched_choose();
if (__predict_false(panicstr != NULL))
return (choosethread_panic(td));
TD_SET_RUNNING(td);
return (td);
}
/*
* Kernel thread preemption implementation. Critical sections mark
* regions of code in which preemptions are not allowed.