From 07d495dae20717b00881798ef812f7aa53ca0eb3 Mon Sep 17 00:00:00 2001 From: Alexander Kuleshov Date: Mon, 28 Nov 2016 13:50:57 +0600 Subject: [PATCH] x86/traps: Get rid of unnecessary preempt_disable/preempt_enable_no_resched Exception handlers which may run on IST stack call ist_enter() at the start of execution and ist_exit() in the end. ist_enter() disables preemption unconditionally and ist_exit() enables it. So the extra preempt_disable/enable() pairs nested inside the ist_enter/exit() regions are pointless and can be removed. Signed-off-by: Alexander Kuleshov Cc: Tony Luck Cc: Jianyu Zhan Cc: Paul Gortmaker Cc: Andy Lutomirski Cc: Borislav Petkov Link: http://lkml.kernel.org/r/20161128075057.7724-1-kuleshovmail@gmail.com Signed-off-by: Thomas Gleixner --- 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 bf0c6d049080..1dc86ee60a03 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: -- 2.20.1