metag: move irq enable out of irqflags.h on SMP

The SMP version of arch_local_irq_enable() uses preempt_disable(), but
<asm/irqflags.h> doesn't include <linux/preempt.h> causing the following
errors on SMP when pstore/ftrace is enabled (caught by buildbot smp
allyesconfig):

In file included from include/linux/irqflags.h:15,
                 from fs/pstore/ftrace.c:16:
arch/metag/include/asm/irqflags.h: In function 'arch_local_irq_enable':
arch/metag/include/asm/irqflags.h:84: error: implicit declaration of function 'preempt_disable'
arch/metag/include/asm/irqflags.h:86: error: implicit declaration of function 'preempt_enable_no_resched'

However <linux/preempt.h> cannot be easily included from
<asm/irqflags.h> as it can cause circular include dependencies in the
!SMP case, and potentially in the SMP case in the future. Therefore move
the SMP implementation of arch_local_irq_enable() into traps.c and use
an inline version of get_trigger_mask() which is also defined in traps.c
for SMP.

This adds an extra layer of function call / stack push when
preempt_disable needs to call other functions, however in the
non-preemptive SMP case it should be about as fast, as it was already
calling the get_trigger_mask() function which is now used inline.

Signed-off-by: James Hogan <james.hogan@imgtec.com>

1 files changed, 5 insertions, 6 deletions

diff --git a/arch/metag/include/asm/irqflags.h b/arch/metag/include/asm/irqflags.h
index cba5e135bc9a..339b16f062eb 100644
--- a/arch/metag/include/asm/irqflags.h
+++ b/arch/metag/include/asm/irqflags.h
@@ -78,16 +78,15 @@ static inline void arch_local_irq_disable(void)
 	asm volatile("MOV TXMASKI,%0\n" : : "r" (flags) : "memory");
 }
 
-static inline void arch_local_irq_enable(void)
-{
 #ifdef CONFIG_SMP
-	preempt_disable();
-	arch_local_irq_restore(get_trigger_mask());
-	preempt_enable_no_resched();
+/* Avoid circular include dependencies through <linux/preempt.h> */
+void arch_local_irq_enable(void);
 #else
+static inline void arch_local_irq_enable(void)
+{
 	arch_local_irq_restore(get_trigger_mask());
-#endif
 }
+#endif
 
 #endif /* (__ASSEMBLY__) */