[IA64] perfmon: make pfm_sysctl a global, and other cleanup

- make pfm_sysctl a global such that it is possible
  to enable/disable debug printk in sampling formats
  using PFM_DEBUG.

- remove unused pfm_debug_var variable

- fix a bug in pfm_handle_work where an BUG_ON() could
  be triggered. There is a path where pfm_handle_work()
  can be called with interrupts enabled, i.e., when
  TIF_NEED_RESCHED is set. The fix correct the masking
  and unmasking of interrupts in pfm_handle_work() such
  that we restore the interrupt mask as it was upon entry.

signed-off-by: stephane eranian <eranian@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

include/asm-ia64/perfmon.h

@@ -254,6 +254,18 @@ extern int pfm_mod_write_dbrs(struct task_struct *task, void *req, unsigned int
 #define PFM_CPUINFO_DCR_PP	0x2	/* if set the system wide session has started */
 #define PFM_CPUINFO_EXCL_IDLE	0x4	/* the system wide session excludes the idle task */
 
+/*
+ * sysctl control structure. visible to sampling formats
+ */
+typedef struct {
+	int	debug;		/* turn on/off debugging via syslog */
+	int	debug_ovfl;	/* turn on/off debug printk in overflow handler */
+	int	fastctxsw;	/* turn on/off fast (unsecure) ctxsw */
+	int	expert_mode;	/* turn on/off value checking */
+} pfm_sysctl_t;
+extern pfm_sysctl_t pfm_sysctl;
+
+
 #endif /* __KERNEL__ */
 
 #endif /* _ASM_IA64_PERFMON_H */