[PATCH] get_cpu_var patch

This makes introduces get_cpu_var()/put_cpu_var() which gets a
per-cpu variable and disables preemption, and renames the (unsafe
under preemption) "this_cpu()" macro to __get_cpu_var().  It also
deletes the redundant definitions in linux/smp.h.

arch/ia64/kernel/perfmon.c

@@ -1764,7 +1764,7 @@ pfm_stop(struct task_struct *task, pfm_context_t *ctx, void *arg, int count,
 		ia64_srlz_i();
 
 #ifdef CONFIG_SMP
-		this_cpu(pfm_dcr_pp)  = 0;
+		__get_cpu_var(pfm_dcr_pp)  = 0;
 #else
 		pfm_tasklist_toggle_pp(0);
 #endif
@@ -2172,7 +2172,7 @@ pfm_start(struct task_struct *task, pfm_context_t *ctx, void *arg, int count,
 	if (ctx->ctx_fl_system) {
 		
 #ifdef CONFIG_SMP
-		this_cpu(pfm_dcr_pp)  = 1;
+		__get_cpu_var(pfm_dcr_pp)  = 1;
 #else
 		pfm_tasklist_toggle_pp(1);
 #endif
@@ -2227,8 +2227,8 @@ pfm_enable(struct task_struct *task, pfm_context_t *ctx, void *arg, int count,
 		ia64_srlz_i();
 
 #ifdef CONFIG_SMP
-		this_cpu(pfm_syst_wide) = 1;
-		this_cpu(pfm_dcr_pp)    = 0;
+		__get_cpu_var(pfm_syst_wide) = 1;
+		__get_cpu_var(pfm_dcr_pp)    = 0;
 #endif
 	} else {
 		/*
@@ -2980,9 +2980,9 @@ perfmon_proc_info(char *page)
 	p += sprintf(p, "CPU%d syst_wide   : %d\n"
 			"CPU%d dcr_pp      : %d\n", 
 			smp_processor_id(), 
-			this_cpu(pfm_syst_wide), 
+			__get_cpu_var(pfm_syst_wide), 
 			smp_processor_id(), 
-			this_cpu(pfm_dcr_pp));
+			__get_cpu_var(pfm_dcr_pp));
 #endif
 
 	LOCK_PFS();
@@ -3052,7 +3052,7 @@ pfm_syst_wide_update_task(struct task_struct *task, int mode)
 	/*
 	 * propagate the value of the dcr_pp bit to the psr
 	 */
-	ia64_psr(regs)->pp = mode ? this_cpu(pfm_dcr_pp) : 0;
+	ia64_psr(regs)->pp = mode ? __get_cpu_var(pfm_dcr_pp) : 0;
 }
 #endif
 
@@ -3546,8 +3546,8 @@ pfm_flush_regs (struct task_struct *task)
 		ia64_srlz_i();
 
 #ifdef CONFIG_SMP
-		this_cpu(pfm_syst_wide) = 0;
-		this_cpu(pfm_dcr_pp)    = 0;
+		__get_cpu_var(pfm_syst_wide) = 0;
+		__get_cpu_var(pfm_dcr_pp)    = 0;
 #else
 		pfm_tasklist_toggle_pp(0);
 #endif

arch/ia64/kernel/process.c

@@ -194,7 +194,7 @@ ia64_save_extra (struct task_struct *task)
 		pfm_save_regs(task);
 
 # ifdef CONFIG_SMP
-	if (this_cpu(pfm_syst_wide))
+	if (__get_cpu_var(pfm_syst_wide))
 		pfm_syst_wide_update_task(task, 0);
 # endif
 #endif
@@ -216,7 +216,7 @@ ia64_load_extra (struct task_struct *task)
 		pfm_load_regs(task);
 
 # ifdef CONFIG_SMP
-	if (this_cpu(pfm_syst_wide)) pfm_syst_wide_update_task(task, 1);
+	if (__get_cpu_var(pfm_syst_wide)) pfm_syst_wide_update_task(task, 1);
 # endif
 #endif
 

arch/ia64/kernel/smp.c

@@ -99,7 +99,7 @@ void
 handle_IPI (int irq, void *dev_id, struct pt_regs *regs)
 {
 	int this_cpu = smp_processor_id();
-	unsigned long *pending_ipis = &this_cpu(ipi_operation);
+	unsigned long *pending_ipis = &__get_cpu_var(ipi_operation);
 	unsigned long ops;
 
 	/* Count this now; we may make a call that never returns. */

include/asm-generic/percpu.h

@@ -8,6 +8,6 @@ extern unsigned long __per_cpu_offset[NR_CPUS];
 
 /* var is in discarded region: offset to particular copy we want */
 #define per_cpu(var, cpu) (*RELOC_HIDE(&var, __per_cpu_offset[cpu]))
-#define this_cpu(var) per_cpu(var, smp_processor_id())
+#define __get_cpu_var(var) per_cpu(var, smp_processor_id())
 
 #endif /* _ASM_GENERIC_PERCPU_H_ */

include/asm-ia64/percpu.h

@@ -17,7 +17,7 @@
 extern unsigned long __per_cpu_offset[NR_CPUS];
 
 #define per_cpu(var, cpu)	(*(__typeof__(&(var))) ((void *) &(var) + __per_cpu_offset[cpu]))
-#define this_cpu(var)		(var)
+#define __get_cpu_var(var)	(var)
 
 #endif /* !__ASSEMBLY__ */
 

include/asm-ia64/processor.h

@@ -181,7 +181,7 @@ extern struct cpuinfo_ia64 {
  * The "local" data pointer.  It points to the per-CPU data of the currently executing
  * CPU, much like "current" points to the per-task data of the currently executing task.
  */
-#define local_cpu_data		(&this_cpu(cpu_info))
+#define local_cpu_data		(&__get_cpu_var(cpu_info))
 #define cpu_data(cpu)		(&per_cpu(cpu_info, cpu))
 
 extern void identify_cpu (struct cpuinfo_ia64 *);

include/asm-x86_64/percpu.h

@@ -4,7 +4,7 @@
 #include <asm/pda.h>
 
 /* var is in discarded region: offset to particular copy we want */
-#define this_cpu(var)     (*RELOC_HIDE(&var, read_pda(cpudata_offset)))
+#define __get_cpu_var(var)     (*RELOC_HIDE(&var, read_pda(cpudata_offset)))
 #define per_cpu(var, cpu) (*RELOC_HIDE(&var, per_cpu_pda[cpu]))
 
 void setup_per_cpu_areas(void);

include/linux/percpu.h

@@ -8,7 +8,9 @@
 #else
 #define __per_cpu_data
 #define per_cpu(var, cpu)			var
-#define this_cpu(var)				var
+#define __get_cpu_var(var)			var
 #endif
 
+#define get_cpu_var(var) ({ preempt_disable(); __get_cpu_var(var); })
+#define put_cpu_var(var) preempt_enable()
 #endif /* __LINUX_PERCPU_H */

include/linux/smp.h

@@ -96,9 +96,6 @@ static inline void smp_send_reschedule_all(void) { }
 #define cpu_online_map				1
 #define cpu_online(cpu)				({ cpu; 1; })
 #define num_online_cpus()			1
-#define __per_cpu_data
-#define per_cpu(var, cpu)			var
-#define this_cpu(var)				var
 
 struct notifier_block;
 

kernel/softirq.c

@@ -159,8 +159,8 @@ void __tasklet_schedule(struct tasklet_struct *t)
 	unsigned long flags;
 
 	local_irq_save(flags);
-	t->next = this_cpu(tasklet_vec).list;
-	this_cpu(tasklet_vec).list = t;
+	t->next = __get_cpu_var(tasklet_vec).list;
+	__get_cpu_var(tasklet_vec).list = t;
 	cpu_raise_softirq(smp_processor_id(), TASKLET_SOFTIRQ);
 	local_irq_restore(flags);
 }
@@ -170,8 +170,8 @@ void __tasklet_hi_schedule(struct tasklet_struct *t)
 	unsigned long flags;
 
 	local_irq_save(flags);
-	t->next = this_cpu(tasklet_hi_vec).list;
-	this_cpu(tasklet_hi_vec).list = t;
+	t->next = __get_cpu_var(tasklet_hi_vec).list;
+	__get_cpu_var(tasklet_hi_vec).list = t;
 	cpu_raise_softirq(smp_processor_id(), HI_SOFTIRQ);
 	local_irq_restore(flags);
 }
@@ -181,8 +181,8 @@ static void tasklet_action(struct softirq_action *a)
 	struct tasklet_struct *list;
 
 	local_irq_disable();
-	list = this_cpu(tasklet_vec).list;
-	this_cpu(tasklet_vec).list = NULL;
+	list = __get_cpu_var(tasklet_vec).list;
+	__get_cpu_var(tasklet_vec).list = NULL;
 	local_irq_enable();
 
 	while (list) {
@@ -202,8 +202,8 @@ static void tasklet_action(struct softirq_action *a)
 		}
 
 		local_irq_disable();
-		t->next = this_cpu(tasklet_vec).list;
-		this_cpu(tasklet_vec).list = t;
+		t->next = __get_cpu_var(tasklet_vec).list;
+		__get_cpu_var(tasklet_vec).list = t;
 		__cpu_raise_softirq(smp_processor_id(), TASKLET_SOFTIRQ);
 		local_irq_enable();
 	}
@@ -214,8 +214,8 @@ static void tasklet_hi_action(struct softirq_action *a)
 	struct tasklet_struct *list;
 
 	local_irq_disable();
-	list = this_cpu(tasklet_hi_vec).list;
-	this_cpu(tasklet_hi_vec).list = NULL;
+	list = __get_cpu_var(tasklet_hi_vec).list;
+	__get_cpu_var(tasklet_hi_vec).list = NULL;
 	local_irq_enable();
 
 	while (list) {
@@ -235,8 +235,8 @@ static void tasklet_hi_action(struct softirq_action *a)
 		}
 
 		local_irq_disable();
-		t->next = this_cpu(tasklet_hi_vec).list;
-		this_cpu(tasklet_hi_vec).list = t;
+		t->next = __get_cpu_var(tasklet_hi_vec).list;
+		__get_cpu_var(tasklet_hi_vec).list = t;
 		__cpu_raise_softirq(smp_processor_id(), HI_SOFTIRQ);
 		local_irq_enable();
 	}