x86-64 runs irq_exit() under the irq stack. So it can afford to run softirqs in hardirq exit without the need to switch the stacks. The hardirq stack is good enough for that.
Now x86-64 runs softirqs in the hardirq stack anyway, so what we mostly skip is some needless per cpu refcounting updates there. x86-32 is not concerned because it only runs the irq handler on the irq stack. Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Benjamin Herrenschmidt <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: James Hogan <[email protected]> Cc: James E.J. Bottomley <[email protected]> Cc: Helge Deller <[email protected]> Cc: Martin Schwidefsky <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: David S. Miller <[email protected]> Cc: Andrew Morton <[email protected]> --- arch/x86/include/asm/irq.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h index 0ea10f27..879bece 100644 --- a/arch/x86/include/asm/irq.h +++ b/arch/x86/include/asm/irq.h @@ -23,6 +23,10 @@ extern void irq_ctx_init(int cpu); #define __ARCH_HAS_DO_SOFTIRQ +#ifdef CONFIG_X86_64 +# define __ARCH_IRQ_EXIT_ON_IRQ_STACK +#endif + #ifdef CONFIG_HOTPLUG_CPU #include <linux/cpumask.h> extern void fixup_irqs(void); -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
