smp.h: Use local_irq_{save,restore}() in !SMP version of on_each_cpu().

Thanks to commit f91eb62f71b3 ("init: scream bloody murder if interrupts
are enabled too early"), "bloody murder" is now being screamed.

With a MIPS OCTEON config, we use on_each_cpu() in our
irq_chip.irq_bus_sync_unlock() function. This gets called in early as a
result of the time_init() call. Because the !SMP version of
on_each_cpu() unconditionally enables irqs, we get:

WARNING: at init/main.c:560 start_kernel+0x250/0x410()
Interrupts were enabled early
CPU: 0 PID: 0 Comm: swapper Not tainted 3.10.0-rc5-Cavium-Octeon+ #801
Call Trace:
show_stack+0x68/0x80
warn_slowpath_common+0x78/0xb0
warn_slowpath_fmt+0x38/0x48
start_kernel+0x250/0x410

Suggested fix: Do what we already do in the SMP version of
on_each_cpu(), and use local_irq_save/local_irq_restore. Because we
need a flags variable, make it a static inline to avoid name space
issues.

[ Change from v1: Convert on_each_cpu to a static inline function, add
#include <linux/irqflags.h> to avoid build breakage on some files.

on_each_cpu_mask() and on_each_cpu_cond() suffer the same problem as
on_each_cpu(), but they are not causing !SMP bugs for me, so I will
defer changing them to a less urgent patch. ]

Signed-off-by: David Daney <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/smp.h

···
 #include <linux/list.h>
 #include <linux/cpumask.h>
 #include <linux/init.h>
+#include <linux/irqflags.h>
 
 extern void cpu_idle(void);
 
···
 }
 #define smp_call_function(func, info, wait) \
 			(up_smp_call_function(func, info))
-#define on_each_cpu(func,info,wait)		\
-	({					\
-		local_irq_disable();		\
-		func(info);			\
-		local_irq_enable();		\
-		0;				\
-	})
+
+static inline int on_each_cpu(smp_call_func_t func, void *info, int wait)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	func(info);
+	local_irq_restore(flags);
+	return 0;
+}
+
 /*
  * Note we still need to test the mask even for UP
  * because we actually can get an empty mask from