linux-kernel - [PATCH] [36/50] x86: Use raw locks during oopses

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Message-Id: <20070921223236.26E361479D@wotan.suse.de>
Date:	Sat, 22 Sep 2007 00:32:36 +0200 (CEST)
From:	Andi Kleen <ak@...e.de>
To:	patches@...-64.org, linux-kernel@...r.kernel.org
Subject: [PATCH] [36/50] x86: Use raw locks during oopses


Don't want any lockdep or other fragile machinery to run during oopses.
Use raw spinlocks directly for oops locking.
Also disables irq flag tracing there.

Signed-off-by: Andi Kleen <ak@...e.de>

---
 arch/i386/kernel/traps.c   |   12 +++++++-----
 arch/x86_64/kernel/traps.c |   17 ++++++++---------
 2 files changed, 15 insertions(+), 14 deletions(-)

Index: linux/arch/i386/kernel/traps.c
===================================================================
--- linux.orig/arch/i386/kernel/traps.c
+++ linux/arch/i386/kernel/traps.c
@@ -447,11 +447,11 @@ void ler_enable(void) {
 void die(const char * str, struct pt_regs * regs, long err)
 {
 	static struct {
-		spinlock_t lock;
+		raw_spinlock_t lock;
 		u32 lock_owner;
 		int lock_owner_depth;
 	} die = {
-		.lock =			__SPIN_LOCK_UNLOCKED(die.lock),
+		.lock =			__RAW_SPIN_LOCK_UNLOCKED,
 		.lock_owner =		-1,
 		.lock_owner_depth =	0
 	};
@@ -462,13 +462,14 @@ void die(const char * str, struct pt_reg
 
 	if (die.lock_owner != raw_smp_processor_id()) {
 		console_verbose();
-		spin_lock_irqsave(&die.lock, flags);
+		__raw_spin_lock(&die.lock);
+		raw_local_save_flags(flags);
 		die.lock_owner = smp_processor_id();
 		die.lock_owner_depth = 0;
 		bust_spinlocks(1);
 	}
 	else
-		local_save_flags(flags);
+		raw_local_save_flags(flags);
 
 	if (++die.lock_owner_depth < 3) {
 		unsigned long esp;
@@ -511,7 +512,8 @@ void die(const char * str, struct pt_reg
 	bust_spinlocks(0);
 	die.lock_owner = -1;
 	add_taint(TAINT_DIE);
-	spin_unlock_irqrestore(&die.lock, flags);
+	__raw_spin_unlock(&die.lock);
+	raw_local_irq_restore(flags);
 
 	if (!regs)
 		return;
Index: linux/arch/x86_64/kernel/traps.c
===================================================================
--- linux.orig/arch/x86_64/kernel/traps.c
+++ linux/arch/x86_64/kernel/traps.c
@@ -556,7 +556,7 @@ void ler_enable(void) {
 	}
 }
 
-static DEFINE_SPINLOCK(die_lock);
+static raw_spinlock_t die_lock = __RAW_SPIN_LOCK_UNLOCKED;
 static int die_owner = -1;
 static unsigned int die_nest_count;
 
@@ -568,13 +568,13 @@ unsigned __kprobes long oops_begin(void)
 	oops_enter();
 
 	/* racy, but better than risking deadlock. */
-	local_irq_save(flags);
+	raw_local_irq_save(flags);
 	cpu = smp_processor_id();
-	if (!spin_trylock(&die_lock)) { 
+	if (!__raw_spin_trylock(&die_lock)) {
 		if (cpu == die_owner) 
 			/* nested oops. should stop eventually */;
 		else
-			spin_lock(&die_lock);
+			__raw_spin_lock(&die_lock);
 	}
 	die_nest_count++;
 	die_owner = cpu;
@@ -588,12 +588,11 @@ void __kprobes oops_end(unsigned long fl
 	die_owner = -1;
 	bust_spinlocks(0);
 	die_nest_count--;
-	if (die_nest_count)
-		/* We still own the lock */
-		local_irq_restore(flags);
-	else
+	if (!die_nest_count) {
 		/* Nest count reaches zero, release the lock. */
-		spin_unlock_irqrestore(&die_lock, flags);
+		__raw_spin_unlock(&die_lock);
+	}
+	raw_local_irq_restore(flags);
 	if (!regs) {
 		oops_exit();
 		return;
-
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