112 lines
2.9 KiB
C
112 lines
2.9 KiB
C
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/*-
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* Copyright (c) 2002 Matthew Dillon. This code is distributed under
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* the BSD copyright, /usr/src/COPYRIGHT.
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*
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* This file contains prototypes and high-level inlines related to
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* machine-level critical function support:
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*
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* cpu_critical_enter() - inlined
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* cpu_critical_exit() - inlined
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* cpu_critical_fork_exit() - prototyped
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* cpu_thread_link() - prototyped
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* related support functions residing
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* in <arch>/<arch>/critical.c - prototyped
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*
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* $FreeBSD$
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*/
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#ifndef _MACHINE_CRITICAL_H_
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#define _MACHINE_CRITICAL_H_
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__BEGIN_DECLS
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extern int critical_mode;
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/*
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* Prototypes - see <arch>/<arch>/critical.c
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*/
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void cpu_unpend(void);
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void cpu_critical_fork_exit(void);
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void cpu_thread_link(struct thread *td);
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#ifdef __GNUC__
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/*
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* cpu_critical_enter:
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*
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* This routine is called from critical_enter() on the 0->1 transition
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* of td_critnest, prior to it being incremented to 1.
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*
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* If old-style critical section handling (critical_mode == 0), we
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* disable interrupts.
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*
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* If new-style critical section handling (criticla_mode != 0), we
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* do not have to do anything. However, as a side effect any
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* interrupts occuring while td_critnest is non-zero will be
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* deferred.
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*/
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static __inline void
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cpu_critical_enter(void)
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{
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if (critical_mode == 0) {
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struct thread *td = curthread;
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td->td_md.md_savecrit = intr_disable();
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}
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}
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/*
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* cpu_critical_exit:
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*
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* This routine is called from critical_exit() on a 1->0 transition
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* of td_critnest, after it has been decremented to 0. We are
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* exiting the last critical section.
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*
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* If td_critnest is -1 this is the 'new' critical_enter()/exit()
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* code (the default critical_mode=1) and we do not have to do
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* anything unless PCPU_GET(int_pending) is non-zero.
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*
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* Note that the td->critnest (1->0) transition interrupt race against
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* our int_pending/unpend() check below is handled by the interrupt
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* code for us, so we do not have to do anything fancy.
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*
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* Otherwise td_critnest contains the saved hardware interrupt state
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* and will be restored. Since interrupts were hard-disabled there
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* will be no pending interrupts to dispatch (the 'original' code).
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*/
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static __inline void
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cpu_critical_exit(void)
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{
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struct thread *td = curthread;
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if (td->td_md.md_savecrit != (register_t)-1) {
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intr_restore(td->td_md.md_savecrit);
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td->td_md.md_savecrit = (register_t)-1;
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} else {
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/*
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* We may have to schedule pending interrupts. Create
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* conditions similar to an interrupt context and call
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* unpend().
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*
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* note: we do this even if we are in an interrupt
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* nesting level. Deep nesting is protected by
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* critical_*() and if we conditionalized it then we
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* would have to check int_pending again whenever
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* we decrement td_intr_nesting_level to 0.
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*/
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if (PCPU_GET(int_pending))
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cpu_unpend();
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}
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}
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#else /* !__GNUC__ */
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void cpu_critical_enter(void)
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void cpu_critical_exit(void)
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#endif /* __GNUC__ */
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__END_DECLS
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#endif /* !_MACHINE_CRITICAL_H_ */
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