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