[PATCH 2/5] percpu struct members.

[PATCH 2/5] percpu struct members.

[Rusty Russell]

Linus, please apply.

The current percpu macros do not allow __get_cpu_var(foo.val1)
which makes building macros on top of them really difficult.  The
reason for this is the __per_cpu postfix appended to per-cpu
variables, designed to catch direct uses.  Prepend it instead.

Name: Allow struct members in percpu macros.
Author: Rusty Russell
Status: Booted on 2.6.0-test1

D: The current percpu macros do not allow __get_cpu_var(foo.val1)
D: which makes building macros on top of them really difficult.  The
D: reason for this is the __per_cpu postfix appended to per-cpu
D: variables, designed to catch direct uses.  Prepend it instead.

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .4837-linux-2.5.75/include/asm-generic/percpu.h .4837-linux-2.5.75.updated/include/asm-generic/percpu.h
--- .4837-linux-2.5.75/include/asm-generic/percpu.h	2003-06-15 11:30:06.000000000 +1000
+++ .4837-linux-2.5.75.updated/include/asm-generic/percpu.h	2003-07-11 16:48:21.000000000 +1000
@@ -9,10 +9,10 @@ extern unsigned long __per_cpu_offset[NR
 
 /* Separate out the type, so (int[3], foo) works. */
 #define DEFINE_PER_CPU(type, name) \
-    __attribute__((__section__(".data.percpu"))) __typeof__(type) name##__per_cpu
+    __attribute__((__section__(".data.percpu"))) __typeof__(type) per_cpu__##name
 
 /* var is in discarded region: offset to particular copy we want */
-#define per_cpu(var, cpu) (*RELOC_HIDE(&var##__per_cpu, __per_cpu_offset[cpu]))
+#define per_cpu(var, cpu) (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]))
 #define __get_cpu_var(var) per_cpu(var, smp_processor_id())
 
 static inline void percpu_modcopy(void *pcpudst, const void *src,
@@ -26,16 +26,16 @@ static inline void percpu_modcopy(void *
 #else /* ! SMP */
 
 #define DEFINE_PER_CPU(type, name) \
-    __typeof__(type) name##__per_cpu
+    __typeof__(type) per_cpu__##name
 
-#define per_cpu(var, cpu)			((void)cpu, var##__per_cpu)
-#define __get_cpu_var(var)			var##__per_cpu
+#define per_cpu(var, cpu)			((void)cpu, per_cpu__##var)
+#define __get_cpu_var(var)			per_cpu__##var
 
 #endif	/* SMP */
 
-#define DECLARE_PER_CPU(type, name) extern __typeof__(type) name##__per_cpu
+#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name
 
-#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var##__per_cpu)
-#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var##__per_cpu)
+#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
+#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
 
 #endif /* _ASM_GENERIC_PERCPU_H_ */
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .4837-linux-2.5.75/include/asm-ia64/percpu.h .4837-linux-2.5.75.updated/include/asm-ia64/percpu.h
--- .4837-linux-2.5.75/include/asm-ia64/percpu.h	2003-06-15 11:30:07.000000000 +1000
+++ .4837-linux-2.5.75.updated/include/asm-ia64/percpu.h	2003-07-11 16:49:38.000000000 +1000
@@ -12,7 +12,7 @@
 
 #ifdef __ASSEMBLY__
 
-#define THIS_CPU(var)	(var##__per_cpu)  /* use this to mark accesses to per-CPU variables... */
+#define THIS_CPU(var)	(per_cpu__##var)  /* use this to mark accesses to per-CPU variables... */
 
 #else /* !__ASSEMBLY__ */
 
@@ -21,20 +21,20 @@
 extern unsigned long __per_cpu_offset[NR_CPUS];
 
 #define DEFINE_PER_CPU(type, name) \
-    __attribute__((__section__(".data.percpu"))) __typeof__(type) name##__per_cpu
-#define DECLARE_PER_CPU(type, name) extern __typeof__(type) name##__per_cpu
+    __attribute__((__section__(".data.percpu"))) __typeof__(type) per_cpu__##name
+#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name
 
-#define __get_cpu_var(var)	(var##__per_cpu)
+#define __get_cpu_var(var)	(per_cpu__##var)
 #ifdef CONFIG_SMP
-# define per_cpu(var, cpu)	(*RELOC_HIDE(&var##__per_cpu, __per_cpu_offset[cpu]))
+# define per_cpu(var, cpu)	(*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]))
 
 extern void percpu_modcopy(void *pcpudst, const void *src, unsigned long size);
 #else
 # define per_cpu(var, cpu)	((void)cpu, __get_cpu_var(var))
 #endif
 
-#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var##__per_cpu)
-#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var##__per_cpu)
+#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
+#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
 
 extern void setup_per_cpu_areas (void);
 

--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.

Re: [PATCH 2/5] percpu struct members.

[Jamie Lokier]

Rusty Russell wrote:
> The current percpu macros do not allow __get_cpu_var(foo.val1)
> which makes building macros on top of them really difficult.

What's the problem with __get_cpu_var(foo).val1 ?

-- Jamie

Re: [PATCH 2/5] percpu struct members.

[Rusty Russell]

In message <20030721185619.GB6912@mail.jlokier.co.uk> you write:
> Rusty Russell wrote:
> > The current percpu macros do not allow __get_cpu_var(foo.val1)
> > which makes building macros on top of them really difficult.
> 
> What's the problem with __get_cpu_var(foo).val1 ?

Nothing: that will still work, too.  But not say you have a macro (as
we do in local_t):

	local_cpu_inc(cpuvar)

if cpuvar is a struct, you want this to work:

	local_cpu_inc(cpuvar.member)

Hope that helps,
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.