Re: Linux 3.10-rc6

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 17 Jun 2013 14:26:01 -0700 David Daney <ddaney@caviumnetworks.com> wrote:

> On 06/17/2013 02:13 PM, Andrew Morton wrote:
> > On Mon, 17 Jun 2013 14:08:13 -0700 David Daney <ddaney@caviumnetworks.com> wrote:
> >
> >>>
> >>> I think switch-back-to-a-macro is simplest and safest for now.  Perhaps
> >>> you can queue a 3.11 patch which restores the C function and fixes up
> >>> mn10300 and ia64?
> >>>
> >>
> >> If the patch is reverted, I will do that.
> >
> > I'm not proposing that we revert f21afc25f9ed4.  Retain its
> > functionality, but do it via a macro for 3.10.
> >
> 
> I misread your patch.  Your patch may be incorrect in that the flags 
> variable you introduce has name space collisions with code using the 
> macro.  Linus found this exact problem with the first version of my 
> patch (which was identical to your patch).

Sigh.  Macros do so suck.

--- a/include/linux/smp.h~include-linux-smph-on_each_cpu-switch-back-to-a-macro
+++ a/include/linux/smp.h
@@ -11,7 +11,6 @@
 #include <linux/list.h>
 #include <linux/cpumask.h>
 #include <linux/init.h>
-#include <linux/irqflags.h>
 
 extern void cpu_idle(void);
 
@@ -140,17 +139,14 @@ static inline int up_smp_call_function(s
 }
 #define smp_call_function(func, info, wait) \
 			(up_smp_call_function(func, info))
-
-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;
-}
-
+#define on_each_cpu(func, info, wait)		\
+	({					\
+		unsigned long __flags;		\
+		local_irq_save(__flags);	\
+		func(info);			\
+		local_irq_restore(__flags);	\
+		0;				\
+	})
 /*
  * Note we still need to test the mask even for UP
  * because we actually can get an empty mask from
_

> Once you fix the name of 'flags', I hope you don't run into the same 
> Include Hell on ia64 and mn10300 that I did.

I build-tested ia64.  I don't have an mn10300 cross-compiler set up.