linux/arch/um/include/longjmp.h

#ifndef __UML_LONGJMP_H
#define __UML_LONGJMP_H

#include <setjmp.h>
#include "os.h"

#define UML_SIGLONGJMP(buf, val) do { \
	siglongjmp(*buf, val);		\
} while(0)

#define UML_SIGSETJMP(buf, enable) ({ \
	int n; \
	enable = get_signals(); \
	n = sigsetjmp(*buf, 1); \
	if(n != 0) \
		set_signals(enable); \
	n; })

#endif
[PATCH] uml: implement soft interrupts This patch implements soft interrupts. Interrupt enabling and disabling no longer map to sigprocmask. Rather, a flag is set indicating whether interrupts may be handled. If a signal comes in and interrupts are marked as OK, then it is handled normally. If interrupts are marked as off, then the signal handler simply returns after noting that a signal needs handling. When interrupts are enabled later on, this pending signals flag is checked, and the IRQ handlers are called at that point. The point of this is to reduce the cost of local_irq_save et al, since they are very much more common than the signals that they are enabling and disabling. Soft interrupts produce a speed-up of ~25% on a kernel build. Subtleties - UML uses sigsetjmp/siglongjmp to switch contexts. sigsetjmp has been wrapped in a save_flags-like macro which remembers the interrupt state at setjmp time, and restores it when it is longjmp-ed back to. The enable_signals function has to loop because the IRQ handler disables interrupts before returning. enable_signals has to return with signals enabled, and signals may come in between the disabling and the return to enable_signals. So, it loops for as long as there are pending signals, ensuring that signals are enabled when it finally returns, and that there are no pending signals that need to be dealt with. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> 2006-01-18 17:42:49 -08:00			`#ifndef __UML_LONGJMP_H`
			`#define __UML_LONGJMP_H`

			`#include <setjmp.h>`
			`#include "os.h"`

			`#define UML_SIGLONGJMP(buf, val) do { \`
			`siglongjmp(*buf, val); \`
			`} while(0)`

			`#define UML_SIGSETJMP(buf, enable) ({ \`
			`int n; \`
			`enable = get_signals(); \`
			`n = sigsetjmp(*buf, 1); \`
			`if(n != 0) \`
			`set_signals(enable); \`
			`n; })`

			`#endif`