perfmon3: X86 OProfile hooks

Index: o3/arch/x86/oprofile/nmi_int.c
===================================================================
@@ -16,6 +16,7 @@
 #include <linux/moduleparam.h>
 #include <linux/kdebug.h>
 #include <linux/cpu.h>
+#include <linux/perfmon_kern.h>
 #include <asm/nmi.h>
 #include <asm/msr.h>
 #include <asm/apic.h>

@@ -217,12 +218,18 @@
 	int err = 0;
 	int cpu;
 
-	if (!allocate_msrs())
+	if (pfm_session_allcpus_acquire())
+		return -EBUSY;
+
+	if (!allocate_msrs()) {
+		pfm_session_allcpus_release();
 		return -ENOMEM;
+	}
 
 	err = register_die_notifier(&profile_exceptions_nb);
 	if (err) {
 		free_msrs();
+		pfm_session_allcpus_release();
 		return err;
 	}
 

@@ -303,6 +310,7 @@
 	msrs = &get_cpu_var(cpu_msrs);
 	model->shutdown(msrs);
 	free_msrs();
+	pfm_session_allcpus_release();
 	put_cpu_var(cpu_msrs);
 }
 

Index: o3/include/linux/perfmon_kern.h
===================================================================
@@ -192,6 +192,9 @@
 
 void pfm_interrupt_handler(unsigned long ip, struct pt_regs *regs);
 
+int pfm_session_allcpus_acquire(void);
+void pfm_session_allcpus_release(void);
+
 static inline void pfm_exit_thread(void)
 {
 	if (current->pfm_context)

@@ -272,5 +275,13 @@
 
 static inline void pfm_ctxsw_out(struct task_struct *p, struct task_struct *n)
 {}
+
+static inline void pfm_session_allcpus_release(void)
+{}
+
+static inline int pfm_session_allcpus_acquire(void)
+{
+	return 0;
+}
 #endif /* CONFIG_PERFMON */
 #endif /* __LINUX_PERFMON_KERN_H__ */

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