5.0-stable patches

[thirdparty/kernel/stable-queue.git] / releases / 2.6.33.2 / sparc64-make-prom-entry-spinlock-nmi-safe.patch

From 8a8187c8fbbd78bd2a2b4b1ad05838d95a4ed91a Mon Sep 17 00:00:00 2001
From: David S. Miller <davem@davemloft.net>
Date: Wed, 3 Mar 2010 09:06:03 -0800
Subject: sparc64: Make prom entry spinlock NMI safe.

From: David S. Miller <davem@davemloft.net>

[ Upstream commit 8a4fd1e4922413cfdfa6c51a59efb720d904a5eb ]

If we do something like try to print to the OF console from an NMI
while we're already in OpenFirmware, we'll deadlock on the spinlock.

Use a raw spinlock and disable NMIs when we take it.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 arch/sparc/prom/p1275.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/arch/sparc/prom/p1275.c
+++ b/arch/sparc/prom/p1275.c
@@ -32,10 +32,9 @@ extern void prom_cif_interface(void);
 extern void prom_cif_callback(void);
 
 /*
- * This provides SMP safety on the p1275buf. prom_callback() drops this lock
- * to allow recursuve acquisition.
+ * This provides SMP safety on the p1275buf.
  */
-DEFINE_SPINLOCK(prom_entry_lock);
+DEFINE_RAW_SPINLOCK(prom_entry_lock);
 
 long p1275_cmd(const char *service, long fmt, ...)
 {
@@ -47,7 +46,9 @@ long p1275_cmd(const char *service, long
 	
 	p = p1275buf.prom_buffer;
 
-	spin_lock_irqsave(&prom_entry_lock, flags);
+	raw_local_save_flags(flags);
+	raw_local_irq_restore(PIL_NMI);
+	raw_spin_lock(&prom_entry_lock);
 
 	p1275buf.prom_args[0] = (unsigned long)p;		/* service */
 	strcpy (p, service);
@@ -139,7 +140,8 @@ long p1275_cmd(const char *service, long
 	va_end(list);
 	x = p1275buf.prom_args [nargs + 3];
 
-	spin_unlock_irqrestore(&prom_entry_lock, flags);
+	raw_spin_unlock(&prom_entry_lock);
+	raw_local_irq_restore(flags);
 
 	return x;
 }