[029/156] sparc64: Make prom entry spinlock NMI safe.
From: Greg KH
Date: Tue Mar 30 2010 - 19:51:33 EST
2.6.33-stable review patch. If anyone has any objections, please let us know.
------------------
From: David S. Miller <davem@xxxxxxxxxxxxx>
[ 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@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
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;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/