Move preemption handling out of critical_exit.
In preperataion for making the enter/exit pair inline. Reviewed by: kib
This commit is contained in:
parent
defd918d79
commit
748b15fc02
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=334062
@ -209,48 +209,49 @@ critical_enter(void)
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(long)td->td_proc->p_pid, td->td_name, td->td_critnest);
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}
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void
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critical_exit(void)
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static void __noinline
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critical_exit_preempt(void)
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{
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struct thread *td;
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int flags;
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td = curthread;
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KASSERT(td->td_owepreempt != 0,
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("critical_exit: td_owepreempt == 0"));
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if (td->td_critnest != 0)
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return;
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if (kdb_active)
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return;
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/*
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* Microoptimization: we committed to switch,
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* disable preemption in interrupt handlers
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* while spinning for the thread lock.
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*/
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td->td_critnest = 1;
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thread_lock(td);
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td->td_critnest--;
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flags = SW_INVOL | SW_PREEMPT;
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if (TD_IS_IDLETHREAD(td))
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flags |= SWT_IDLE;
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else
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flags |= SWT_OWEPREEMPT;
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mi_switch(flags, NULL);
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thread_unlock(td);
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}
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void
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critical_exit(void)
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{
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struct thread *td;
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td = curthread;
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KASSERT(td->td_critnest != 0,
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("critical_exit: td_critnest == 0"));
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if (td->td_critnest == 1) {
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td->td_critnest = 0;
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/*
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* Interrupt handlers execute critical_exit() on
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* leave, and td_owepreempt may be left set by an
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* interrupt handler only when td_critnest > 0. If we
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* are decrementing td_critnest from 1 to 0, read
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* td_owepreempt after decrementing, to not miss the
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* preempt. Disallow compiler to reorder operations.
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*/
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__compiler_membar();
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if (td->td_owepreempt && !kdb_active) {
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/*
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* Microoptimization: we committed to switch,
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* disable preemption in interrupt handlers
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* while spinning for the thread lock.
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*/
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td->td_critnest = 1;
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thread_lock(td);
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td->td_critnest--;
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flags = SW_INVOL | SW_PREEMPT;
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if (TD_IS_IDLETHREAD(td))
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flags |= SWT_IDLE;
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else
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flags |= SWT_OWEPREEMPT;
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mi_switch(flags, NULL);
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thread_unlock(td);
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}
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} else
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td->td_critnest--;
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td->td_critnest--;
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__compiler_membar();
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if (__predict_false(td->td_owepreempt))
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critical_exit_preempt();
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CTR4(KTR_CRITICAL, "critical_exit by thread %p (%ld, %s) to %d", td,
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(long)td->td_proc->p_pid, td->td_name, td->td_critnest);
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}
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