powerpc/rtas: Turn rtas lock into a raw spinlock

[safe/jmp/linux-2.6] / arch / powerpc / kernel / rtas.c

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index ee4c760..d9a9974 100644 (file)
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -40,7 +40,7 @@
 #include <asm/atomic.h>
 
 struct rtas_t rtas = {
-       .lock = SPIN_LOCK_UNLOCKED
+       .lock = __RAW_SPIN_LOCK_UNLOCKED
 };
 EXPORT_SYMBOL(rtas);
 
@@ -67,6 +67,28 @@ unsigned long rtas_rmo_buf;
 void (*rtas_flash_term_hook)(int);
 EXPORT_SYMBOL(rtas_flash_term_hook);
 
+/* RTAS use home made raw locking instead of spin_lock_irqsave
+ * because those can be called from within really nasty contexts
+ * such as having the timebase stopped which would lockup with
+ * normal locks and spinlock debugging enabled
+ */
+static unsigned long lock_rtas(void)
+{
+       unsigned long flags;
+
+       local_irq_save(flags);
+       preempt_disable();
+       __raw_spin_lock_flags(&rtas.lock, flags);
+       return flags;
+}
+
+static void unlock_rtas(unsigned long flags)
+{
+       __raw_spin_unlock(&rtas.lock);
+       local_irq_restore(flags);
+       preempt_enable();
+}
+
 /*
  * call_rtas_display_status and call_rtas_display_status_delay
  * are designed only for very early low-level debugging, which
@@ -79,7 +101,7 @@ static void call_rtas_display_status(char c)
 
        if (!rtas.base)
                return;
-       spin_lock_irqsave(&rtas.lock, s);
+       s = lock_rtas();
 
        args->token = 10;
        args->nargs = 1;
@@ -89,7 +111,7 @@ static void call_rtas_display_status(char c)
 
        enter_rtas(__pa(args));
 
-       spin_unlock_irqrestore(&rtas.lock, s);
+       unlock_rtas(s);
 }
 
 static void call_rtas_display_status_delay(char c)
@@ -411,8 +433,7 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
        if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
                return -1;
 
-       /* Gotta do something different here, use global lock for now... */
-       spin_lock_irqsave(&rtas.lock, s);
+       s = lock_rtas();
        rtas_args = &rtas.args;
 
        rtas_args->token = token;
@@ -439,8 +460,7 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
                        outputs[i] = rtas_args->rets[i+1];
        ret = (nret > 0)? rtas_args->rets[0]: 0;
 
-       /* Gotta do something different here, use global lock for now... */
-       spin_unlock_irqrestore(&rtas.lock, s);
+       unlock_rtas(s);
 
        if (buff_copy) {
                log_error(buff_copy, ERR_TYPE_RTAS_LOG, 0);
@@ -837,7 +857,7 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
 
        buff_copy = get_errorlog_buffer();
 
-       spin_lock_irqsave(&rtas.lock, flags);
+       flags = lock_rtas();
 
        rtas.args = args;
        enter_rtas(__pa(&rtas.args));
@@ -848,7 +868,7 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
        if (args.rets[0] == -1)
                errbuf = __fetch_rtas_last_error(buff_copy);
 
-       spin_unlock_irqrestore(&rtas.lock, flags);
+       unlock_rtas(flags);
 
        if (buff_copy) {
                if (errbuf)