Commit-ID: 07d495dae20717b00881798ef812f7aa53ca0eb3 Gitweb: http://git.kernel.org/tip/07d495dae20717b00881798ef812f7aa53ca0eb3 Author: Alexander Kuleshov <kuleshovm...@gmail.com> AuthorDate: Mon, 28 Nov 2016 13:50:57 +0600 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Sat, 4 Feb 2017 09:36:59 +0100
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 <kuleshovm...@gmail.com> Cc: Tony Luck <tony.l...@intel.com> Cc: Jianyu Zhan <nasa4...@gmail.com> Cc: Paul Gortmaker <paul.gortma...@windriver.com> Cc: Andy Lutomirski <l...@kernel.org> Cc: Borislav Petkov <b...@suse.de> Link: http://lkml.kernel.org/r/20161128075057.7724-1-kuleshovm...@gmail.com Signed-off-by: Thomas Gleixner <t...@linutronix.de> --- 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 bf0c6d0..1dc86ee 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:
