Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754445AbcK1HvP (ORCPT ); Mon, 28 Nov 2016 02:51:15 -0500 Received: from mail-lf0-f66.google.com ([209.85.215.66]:34200 "EHLO mail-lf0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753860AbcK1HvH (ORCPT ); Mon, 28 Nov 2016 02:51:07 -0500 From: Alexander Kuleshov To: Thomas Gleixner Cc: Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, Andy Lutomirski , Borislav Petkov , Tony Luck , Jianyu Zhan , Paul Gortmaker , linux-kernel@vger.kernel.org, Alexander Kuleshov Subject: [PATCH] x86/traps: get rid of unnecessary preempt_disable/preempt_enable_no_resched Date: Mon, 28 Nov 2016 13:50:57 +0600 Message-Id: <20161128075057.7724-1-kuleshovmail@gmail.com> X-Mailer: git-send-email 2.8.0.rc3.1353.gea9bdc0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1859 Lines: 54 Exception handlers which may run on IST stack calls ist_enter() at the start of execution and ist_exit() in the end. The ist_enter() disables preemption unconditionally and ist_exit() enables it. Besides this, such exception handlers do additional unnecessary calls of preempt_disable() and preempt_enable_no_resched() after/before ist_enter()/ist_exit(). Let's get rid from them. Signed-off-by: Alexander Kuleshov --- arch/x86/kernel/traps.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index bd4e3d4..5fbff64 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -563,11 +563,9 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) * as we may switch to the interrupt stack. */ debug_stack_usage_inc(); - preempt_disable(); cond_local_irq_enable(regs); do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL); cond_local_irq_disable(regs); - preempt_enable_no_resched(); debug_stack_usage_dec(); exit: ist_exit(regs); @@ -742,14 +740,12 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code) debug_stack_usage_inc(); /* It's safe to allow irq's after DR6 has been saved */ - preempt_disable(); cond_local_irq_enable(regs); if (v8086_mode(regs)) { handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, X86_TRAP_DB); cond_local_irq_disable(regs); - preempt_enable_no_resched(); debug_stack_usage_dec(); goto exit; } @@ -769,7 +765,6 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code) if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp) send_sigtrap(tsk, regs, error_code, si_code); cond_local_irq_disable(regs); - preempt_enable_no_resched(); debug_stack_usage_dec(); exit: -- 2.8.0.rc3.1353.gea9bdc0