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/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ee2fb9d..99eb1cc 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -123,6 +123,7 @@ config X86 select COMPAT_OLD_SIGACTION if IA32_EMULATION select RTC_LIB select HAVE_DEBUG_STACKOVERFLOW + select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 config INSTRUCTION_DECODER def_bool y -- 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/
