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Coccinelle script for __get_cpu_var conversion

PATCH In review Christoph Lameter 1 participant 3 messages Aug 26, 2013 1 message not in the archive

Subsystems (4)
x86 Generic include/asm header files Per-CPU memory allocator Coccinelle/Semantic Patches (SmPL)
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A message that is not in the archive (sent off-list or not yet received): [email protected]

Christoph Lameter

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#1 lore raw

PATCH v2 1/31 x86: Use this_cpu_inc/dec for debug registers

I think this patch already exists in one form or another in some x86 tree.

Signed-off-by Christoph Lameter <[email protected]>
arch/x86/include/asm/debugreg.h +2 -2
Index: linux/arch/x86/include/asm/debugreg.h
===================================================================
@@ -97,11 +97,11 @@ extern void hw_breakpoint_restore(void);
 DECLARE_PER_CPU(int, debug_stack_usage);
 static inline void debug_stack_usage_inc(void)
 {
-	__get_cpu_var(debug_stack_usage)++;
+	__this_cpu_inc(debug_stack_usage);
 }
 static inline void debug_stack_usage_dec(void)
 {
-	__get_cpu_var(debug_stack_usage)--;
+	__this_cpu_dec(debug_stack_usage);
 }
 int is_debug_stack(unsigned long addr);
 void debug_stack_set_zero(void);
arch/x86/kernel/cpu/common.c +3 -3
Index: linux/arch/x86/kernel/cpu/common.c
===================================================================
@@ -1144,9 +1144,9 @@ DEFINE_PER_CPU(int, debug_stack_usage);
 
 int is_debug_stack(unsigned long addr)
 {
-	return __get_cpu_var(debug_stack_usage) ||
-		(addr <= __get_cpu_var(debug_stack_addr) &&
-		 addr > (__get_cpu_var(debug_stack_addr) - DEBUG_STKSZ));
+	return __this_cpu_read(debug_stack_usage) ||
+		(addr <= __this_cpu_read(debug_stack_addr) &&
+		 addr > (__this_cpu_read(debug_stack_addr) - DEBUG_STKSZ));
 }
 
 DEFINE_PER_CPU(u32, debug_idt_ctr);
author
#2 lore raw

PATCH v2 2/31 percpu: Make __verify_pcu_ptr handle per cpu pointers to arrays

In reply to a message not in the archive

__verify_pcpu_ptr() will cause a compilation failure if the type of the pointer is a pointer to a fixed array of objects. Adding zero to the pointer converts the type of pointer to that pointing to a single object of the array.

Signed-off-by Christoph Lameter <[email protected]>
include/linux/percpu-defs.h +4 -1
Index: linux/include/linux/percpu-defs.h
===================================================================
@@ -22,9 +22,12 @@
  * Macro which verifies @ptr is a percpu pointer without evaluating
  * @ptr.  This is to be used in percpu accessors to verify that the
  * input parameter is a percpu pointer.
+ *
+ * + 0 is required in order to convert the pointer type from a
+ * potential array type to a pointer to a single item of the array.
  */
 #define __verify_pcpu_ptr(ptr)	do {					\
-	const void __percpu *__vpp_verify = (typeof(ptr))NULL;		\
+	const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL;	\
 	(void)__vpp_verify;						\
 } while (0)
author
#3 lore raw

PATCH v2 3/31 Coccinelle script for __get_cpu_var conversion

In reply to a message not in the archive

Much of the work was done by this coccinelle script.

Wont catch everything (since coccinelle aborts when it no longer can make sense out of macros, sigh) but it covers a lot of ground.

Signed-off-by Christoph Lameter <[email protected]>
scripts/coccinelle/convert/__get_cpu_var.cocci new file +70 -0
Index: linux/scripts/coccinelle/convert/__get_cpu_var.cocci
===================================================================
@@ -0,0 +1,70 @@
+// Convert all &__get_cpu_var to this_cpu_ptr
+//
+// _get_cpu_var is defined as:
+//
+// #define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
+//
+//&__get_cpu_var() is therefore
+//
+//	this_cpu_ptr(&var);
+//
+// The use of this_cpu_ptr() instead of __get_cpu_var clarifies
+// that we are relocating a per cpu offset and that there are
+// no get/put semantics involved.
+//
+//
+// Convert all &__get_cpu_vars (and also related functions)
+// to this_cpu_ptr(). Multiple transformations are provided
+// to be able to beautify the source a bit.
+//
+// Christoph Lameter <[email protected]> August 20, 2013
+//
+
+@A@ expression E; @@
+
+...
+-(&__get_cpu_var(E))
++this_cpu_ptr(&E)
+...
+
+@B@ expression E; @@
+
+...
+-(&__raw_get_cpu_var(E))
++__this_cpu_ptr(&E)
+...
+
+@C@ expression E; @@
+
+...
+-&__get_cpu_var(E)
++this_cpu_ptr(&E)
+...
+
+@D@ expression E; @@
+
+...
+-&__raw_get_cpu_var(E)
++__this_cpu_ptr(&E)
+...
+
+@A2@ expression E; @@
+
+-(&__get_cpu_var(E))
++this_cpu_ptr(&E)
+
+@B2@ expression E; @@
+
+-(&__raw_get_cpu_var(E))
++__this_cpu_ptr(&E)
+
+@C2@ expression E; @@
+
+-&__get_cpu_var(E)
++this_cpu_ptr(&E)
+
+@D2@ expression E; @@
+
+-&__raw_get_cpu_var(E)
++__this_cpu_ptr(&E)
+