sparc64: Make prom entry spinlock NMI safe.

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>

diff --git a/arch/sparc/prom/p1275.c b/arch/sparc/prom/p1275.c
index 4b7c937..2d8b70d 100644 (file)
--- 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 fmt, ...)
        
        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 fmt, ...)
        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;
 }