From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753341AbbDBM0r (ORCPT ); Thu, 2 Apr 2015 08:26:47 -0400 Received: from terminus.zytor.com ([198.137.202.10]:60481 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752864AbbDBM0l (ORCPT ); Thu, 2 Apr 2015 08:26:41 -0400 Date: Thu, 2 Apr 2015 05:26:12 -0700 From: tip-bot for Denys Vlasenko Message-ID: Cc: hpa@zytor.com, luto@amacapital.net, bp@alien8.de, mingo@kernel.org, linux-kernel@vger.kernel.org, oleg@redhat.com, torvalds@linux-foundation.org, ast@plumgrid.com, wad@chromium.org, fweisbec@gmail.com, keescook@chromium.org, tglx@linutronix.de, rostedt@goodmis.org, dvlasenk@redhat.com Reply-To: luto@amacapital.net, bp@alien8.de, linux-kernel@vger.kernel.org, mingo@kernel.org, oleg@redhat.com, hpa@zytor.com, keescook@chromium.org, wad@chromium.org, fweisbec@gmail.com, tglx@linutronix.de, rostedt@goodmis.org, dvlasenk@redhat.com, torvalds@linux-foundation.org, ast@plumgrid.com In-Reply-To: <1427821211-25099-5-git-send-email-dvlasenk@redhat.com> References: <1427821211-25099-5-git-send-email-dvlasenk@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/asm/entry/64: Simplify looping around preempt_schedule_irq() Git-Commit-ID: 36acef2510853e2831047ca9e22d333ba7a1047b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 36acef2510853e2831047ca9e22d333ba7a1047b Gitweb: http://git.kernel.org/tip/36acef2510853e2831047ca9e22d333ba7a1047b Author: Denys Vlasenko AuthorDate: Tue, 31 Mar 2015 19:00:07 +0200 Committer: Ingo Molnar CommitDate: Wed, 1 Apr 2015 13:17:39 +0200 x86/asm/entry/64: Simplify looping around preempt_schedule_irq() At the 'exit_intr' label we test whether interrupt/exception was in kernel. If it did, we jump to the preemption check. If preemption does happen (IOW if we call preempt_schedule_irq()), we go back to 'exit_intr'. But it's pointless, we already know that the test succeeded last time, preemption doesn't change the fact that interrupt/exception was in the kernel. We can go back directly to checking PER_CPU_VAR(__preempt_count) instead. This makes the 'exit_intr' label unused, drop it. Signed-off-by: Denys Vlasenko Cc: Alexei Starovoitov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Steven Rostedt Cc: Will Drewry Link: http://lkml.kernel.org/r/1427821211-25099-5-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/entry_64.S | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 9f8d01f..bad285d 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -654,7 +654,6 @@ ret_from_intr: CFI_DEF_CFA_REGISTER rsp CFI_ADJUST_CFA_OFFSET RBP -exit_intr: testl $3,CS(%rsp) je retint_kernel /* Interrupt came from user space */ @@ -741,12 +740,12 @@ retint_kernel: #ifdef CONFIG_PREEMPT /* Interrupts are off */ /* Check if we need preemption */ - cmpl $0,PER_CPU_VAR(__preempt_count) - jnz 1f bt $9,EFLAGS(%rsp) /* interrupts were off? */ jnc 1f +0: cmpl $0,PER_CPU_VAR(__preempt_count) + jnz 1f call preempt_schedule_irq - jmp exit_intr + jmp 0b 1: #endif /*