linux-kernel - [PATCH 2/7] powerpc: Use die_spin_lock

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Date:	Tue, 24 Feb 2015 14:30:29 +1100
From:	Anton Blanchard <anton@...ba.org>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Paul Mackerras <paulus@...ba.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	sam.bobroff@....ibm.com, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
	Russell King <linux@....linux.org.uk>, peterz@...radead.org,
	Don Zickus <dzickus@...hat.com>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: [PATCH 2/7] powerpc: Use die_spin_lock_{irqsave,irqrestore}

Replace the powerpc specific oops locking with the common one.

Signed-off-by: Anton Blanchard <anton@...ba.org>
---
 arch/powerpc/kernel/traps.c | 24 +++---------------------
 1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 19e4744..4cc1e72 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -36,6 +36,7 @@
 #include <linux/debugfs.h>
 #include <linux/ratelimit.h>
 #include <linux/context_tracking.h>
+#include <linux/die_lock.h>
 
 #include <asm/emulated_ops.h>
 #include <asm/pgtable.h>
@@ -109,14 +110,10 @@ static void pmac_backlight_unblank(void)
 static inline void pmac_backlight_unblank(void) { }
 #endif
 
-static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
-static int die_owner = -1;
-static unsigned int die_nest_count;
 static int die_counter;
 
 static unsigned __kprobes long oops_begin(struct pt_regs *regs)
 {
-	int cpu;
 	unsigned long flags;
 
 	if (debugger(regs))
@@ -124,17 +121,7 @@ static unsigned __kprobes long oops_begin(struct pt_regs *regs)
 
 	oops_enter();
 
-	/* racy, but better than risking deadlock. */
-	raw_local_irq_save(flags);
-	cpu = smp_processor_id();
-	if (!arch_spin_trylock(&die_lock)) {
-		if (cpu == die_owner)
-			/* nested oops. should stop eventually */;
-		else
-			arch_spin_lock(&die_lock);
-	}
-	die_nest_count++;
-	die_owner = cpu;
+	die_spin_lock_irqsave(flags);
 	console_verbose();
 	bust_spinlocks(1);
 	if (machine_is(powermac))
@@ -146,15 +133,10 @@ static void __kprobes oops_end(unsigned long flags, struct pt_regs *regs,
 			       int signr)
 {
 	bust_spinlocks(0);
-	die_owner = -1;
 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
-	die_nest_count--;
 	oops_exit();
 	printk("\n");
-	if (!die_nest_count)
-		/* Nest count reaches zero, release the lock. */
-		arch_spin_unlock(&die_lock);
-	raw_local_irq_restore(flags);
+	die_spin_unlock_irqrestore(flags);
 
 	crash_fadump(regs, "die oops");
 
-- 
2.1.0

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