linux-kernel - [tip:x86/asm] x86/entry: Make irqs_disabled checks in exit code depend on lockdep

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Date:	Fri, 9 Oct 2015 06:14:05 -0700
From:	tip-bot for Andy Lutomirski <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	bp@...en8.de, tglx@...utronix.de, brgerst@...il.com,
	peterz@...radead.org, luto@...capital.net, hpa@...or.com,
	dvlasenk@...hat.com, torvalds@...ux-foundation.org,
	luto@...nel.org, linux-kernel@...r.kernel.org, mingo@...nel.org
Subject: [tip:x86/asm] x86/entry:
  Make irqs_disabled checks in exit code depend on lockdep

Commit-ID:  460d12453e1afe20416ce9536cfecb31d17a9abd
Gitweb:     http://git.kernel.org/tip/460d12453e1afe20416ce9536cfecb31d17a9abd
Author:     Andy Lutomirski <luto@...nel.org>
AuthorDate: Mon, 5 Oct 2015 17:48:18 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 9 Oct 2015 09:41:11 +0200

x86/entry: Make irqs_disabled checks in exit code depend on lockdep

These checks are quite slow.  Disable them in non-lockdep
kernels to reduce the performance hit.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org
Link: http://lkml.kernel.org/r/eccff2a154ae6fb50f40228901003a6e9c24f3d0.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/entry/common.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 0d1c842..03aacd1 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -219,7 +219,7 @@ static struct thread_info *pt_regs_to_thread_info(struct pt_regs *regs)
 /* Called with IRQs disabled. */
 __visible void prepare_exit_to_usermode(struct pt_regs *regs)
 {
-	if (WARN_ON(!irqs_disabled()))
+	if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN_ON(!irqs_disabled()))
 		local_irq_disable();
 
 	lockdep_sys_exit();
@@ -281,8 +281,8 @@ __visible void syscall_return_slowpath(struct pt_regs *regs)
 
 	CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
 
-	if (WARN(irqs_disabled(), "syscall %ld left IRQs disabled",
-		 regs->orig_ax))
+	if (IS_ENABLED(CONFIG_PROVE_LOCKING) &&
+	    WARN(irqs_disabled(), "syscall %ld left IRQs disabled", regs->orig_ax))
 		local_irq_enable();
 
 	/*
--
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