Revert "Oprofile Multiplexing Patch"

Reverting commit 1a960b40 for the main
branch. Multiplexing will be tracked on a separate feature branch.

Conflicts:

    arch/x86/oprofile/nmi_int.c

arch/x86/oprofile/nmi_int.c

@@ -23,18 +23,12 @@
 #include "op_counter.h"
 #include "op_x86_model.h"
 
-DEFINE_PER_CPU(int, switch_index);
-
 static struct op_x86_model_spec const *model;
 static DEFINE_PER_CPU(struct op_msrs, cpu_msrs);
 static DEFINE_PER_CPU(unsigned long, saved_lvtpc);
 
 static int nmi_start(void);
 static void nmi_stop(void);
-static void nmi_cpu_save_mpx_registers(struct op_msrs *msrs);
-static void nmi_cpu_restore_mpx_registers(struct op_msrs *msrs);
-static void nmi_cpu_stop(void *dummy);
-static void nmi_cpu_start(void *dummy);
 
 /* 0 == registered but off, 1 == registered and on */
 static int nmi_enabled = 0;
@@ -87,47 +81,6 @@ static void exit_sysfs(void)
 #define exit_sysfs() do { } while (0)
 #endif /* CONFIG_PM */
 
-static void nmi_cpu_switch(void *dummy)
-{
-	int cpu = smp_processor_id();
-	int si = per_cpu(switch_index, cpu);
-	struct op_msrs *msrs = &per_cpu(cpu_msrs, cpu);
-
-	nmi_cpu_stop(NULL);
-	nmi_cpu_save_mpx_registers(msrs);
-
-	/* move to next set */
-	si += model->num_hardware_counters;
-	if ((si > model->num_counters) || (counter_config[si].count == 0))
-		per_cpu(switch_index, smp_processor_id()) = 0;
-	else
-		per_cpu(switch_index, smp_processor_id()) = si;
-
-	nmi_cpu_restore_mpx_registers(msrs);
-	model->setup_ctrs(msrs);
-	nmi_cpu_start(NULL);
-}
-
-/*
- * Quick check to see if multiplexing is necessary.
- * The check should be sufficient since counters are used
- * in ordre.
- */
-static int nmi_multiplex_on(void)
-{
-	return counter_config[model->num_hardware_counters].count ? 0 : -EINVAL;
-}
-
-static int nmi_switch_event(void)
-{
-	if (nmi_multiplex_on() < 0)
-		return -EINVAL;
-
-	on_each_cpu(nmi_cpu_switch, NULL, 1);
-
-	return 0;
-}
-
 static int profile_exceptions_notify(struct notifier_block *self,
 				     unsigned long val, void *data)
 {
@@ -191,10 +144,11 @@ static void free_msrs(void)
 
 static int allocate_msrs(void)
 {
-	int i, success = 1;
+	int success = 1;
 	size_t controls_size = sizeof(struct op_msr) * model->num_controls;
 	size_t counters_size = sizeof(struct op_msr) * model->num_counters;
 
+	int i;
 	for_each_possible_cpu(i) {
 		per_cpu(cpu_msrs, i).counters = kmalloc(counters_size,
 								GFP_KERNEL);
@@ -202,8 +156,8 @@ static int allocate_msrs(void)
 			success = 0;
 			break;
 		}
-		per_cpu(cpu_msrs, i).controls =
-				kmalloc(controls_size, GFP_KERNEL);
+		per_cpu(cpu_msrs, i).controls = kmalloc(controls_size,
+								GFP_KERNEL);
 		if (!per_cpu(cpu_msrs, i).controls) {
 			success = 0;
 			break;
@@ -247,8 +201,7 @@ static int nmi_setup(void)
 		return err;
 	}
 
-	/*
-	 * We need to serialize save and setup for HT because the subset
+	/* We need to serialize save and setup for HT because the subset
 	 * of msrs are distinct for save and setup operations
 	 */
 
@@ -264,6 +217,7 @@ static int nmi_setup(void)
 				per_cpu(cpu_msrs, 0).controls,
 				sizeof(struct op_msr) * model->num_controls);
 		}
+
 	}
 	on_each_cpu(nmi_save_registers, NULL, 1);
 	on_each_cpu(nmi_cpu_setup, NULL, 1);
@@ -271,41 +225,7 @@ static int nmi_setup(void)
 	return 0;
 }
 
-static void nmi_cpu_save_mpx_registers(struct op_msrs *msrs)
-{
-	unsigned int si = __get_cpu_var(switch_index);
-	unsigned int const nr_ctrs = model->num_hardware_counters;
-	struct op_msr *counters = &msrs->counters[si];
-	unsigned int i;
-
-	for (i = 0; i < nr_ctrs; ++i) {
-		int offset = i + si;
-		if (counters[offset].addr) {
-			rdmsr(counters[offset].addr,
-				counters[offset].multiplex.low,
-				counters[offset].multiplex.high);
-		}
-	}
-}
-
-static void nmi_cpu_restore_mpx_registers(struct op_msrs *msrs)
-{
-	unsigned int si = __get_cpu_var(switch_index);
-	unsigned int const nr_ctrs = model->num_hardware_counters;
-	struct op_msr *counters = &msrs->counters[si];
-	unsigned int i;
-
-	for (i = 0; i < nr_ctrs; ++i) {
-		int offset = i + si;
-		if (counters[offset].addr) {
-			wrmsr(counters[offset].addr,
-				counters[offset].multiplex.low,
-				counters[offset].multiplex.high);
-		}
-	}
-}
-
-static void nmi_cpu_restore_registers(struct op_msrs *msrs)
+static void nmi_restore_registers(struct op_msrs *msrs)
 {
 	unsigned int const nr_ctrs = model->num_counters;
 	unsigned int const nr_ctrls = model->num_controls;
@@ -345,8 +265,7 @@ static void nmi_cpu_shutdown(void *dummy)
 	apic_write(APIC_LVTERR, v | APIC_LVT_MASKED);
 	apic_write(APIC_LVTPC, per_cpu(saved_lvtpc, cpu));
 	apic_write(APIC_LVTERR, v);
-	nmi_cpu_restore_registers(msrs);
-	__get_cpu_var(switch_index) = 0;
+	nmi_restore_registers(msrs);
 }
 
 static void nmi_shutdown(void)
@@ -409,7 +328,6 @@ static int nmi_create_files(struct super_block *sb, struct dentry *root)
 		oprofilefs_create_ulong(sb, dir, "unit_mask", &counter_config[i].unit_mask);
 		oprofilefs_create_ulong(sb, dir, "kernel", &counter_config[i].kernel);
 		oprofilefs_create_ulong(sb, dir, "user", &counter_config[i].user);
-		counter_config[i].save_count_low = 0;
 	}
 
 	return 0;
@@ -551,14 +469,12 @@ int __init op_nmi_init(struct oprofile_operations *ops)
 	}
 
 	/* default values, can be overwritten by model */
-	__raw_get_cpu_var(switch_index) = 0;
 	ops->create_files = nmi_create_files;
 	ops->setup = nmi_setup;
 	ops->shutdown = nmi_shutdown;
 	ops->start = nmi_start;
 	ops->stop = nmi_stop;
 	ops->cpu_type = cpu_type;
-	ops->switch_events = nmi_switch_event;
 
 	if (model->init)
 		ret = model->init(ops);

arch/x86/oprofile/op_counter.h

@@ -10,14 +10,13 @@
 #ifndef OP_COUNTER_H
 #define OP_COUNTER_H
  
-#define OP_MAX_COUNTER 32
+#define OP_MAX_COUNTER 8
  
 /* Per-perfctr configuration as set via
  * oprofilefs.
  */
 struct op_counter_config {
         unsigned long count;
-		unsigned long save_count_low;
         unsigned long enabled;
         unsigned long event;
         unsigned long kernel;

arch/x86/oprofile/op_model_amd.c

@@ -15,7 +15,6 @@
 #include <linux/oprofile.h>
 #include <linux/device.h>
 #include <linux/pci.h>
-#include <linux/percpu.h>
 
 #include <asm/ptrace.h>
 #include <asm/msr.h>
@@ -24,10 +23,8 @@
 #include "op_x86_model.h"
 #include "op_counter.h"
 
-#define NUM_COUNTERS 32
-#define NUM_HARDWARE_COUNTERS 4
-#define NUM_CONTROLS 32
-#define NUM_HARDWARE_CONTROLS 4
+#define NUM_COUNTERS 4
+#define NUM_CONTROLS 4
 
 #define CTR_IS_RESERVED(msrs, c) (msrs->counters[(c)].addr ? 1 : 0)
 #define CTR_READ(l, h, msrs, c) do {rdmsr(msrs->counters[(c)].addr, (l), (h)); } while (0)
@@ -51,7 +48,6 @@
 #define CTRL_SET_GUEST_ONLY(val, h) (val |= ((h & 1) << 8))
 
 static unsigned long reset_value[NUM_COUNTERS];
-DECLARE_PER_CPU(int, switch_index);
 
 #ifdef CONFIG_OPROFILE_IBS
 
@@ -134,17 +130,15 @@ static void op_amd_fill_in_addresses(struct op_msrs * const msrs)
 	int i;
 
 	for (i = 0; i < NUM_COUNTERS; i++) {
-		int hw_counter = i % NUM_HARDWARE_COUNTERS;
-		if (reserve_perfctr_nmi(MSR_K7_PERFCTR0 + hw_counter))
-			msrs->counters[i].addr = MSR_K7_PERFCTR0 + hw_counter;
+		if (reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i))
+			msrs->counters[i].addr = MSR_K7_PERFCTR0 + i;
 		else
 			msrs->counters[i].addr = 0;
 	}
 
 	for (i = 0; i < NUM_CONTROLS; i++) {
-		int hw_control = i % NUM_HARDWARE_CONTROLS;
-		if (reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + hw_control))
-			msrs->controls[i].addr = MSR_K7_EVNTSEL0 + hw_control;
+		if (reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i))
+			msrs->controls[i].addr = MSR_K7_EVNTSEL0 + i;
 		else
 			msrs->controls[i].addr = 0;
 	}
@@ -156,16 +150,8 @@ static void op_amd_setup_ctrs(struct op_msrs const * const msrs)
 	unsigned int low, high;
 	int i;
 
-	for (i = 0; i < NUM_HARDWARE_CONTROLS; ++i) {
-		int offset = i + __get_cpu_var(switch_index);
-		if (counter_config[offset].enabled)
-			reset_value[offset] = counter_config[offset].count;
-		else
-			reset_value[offset] = 0;
-	}
-
 	/* clear all counters */
-	for (i = 0 ; i < NUM_HARDWARE_CONTROLS; ++i) {
+	for (i = 0 ; i < NUM_CONTROLS; ++i) {
 		if (unlikely(!CTRL_IS_RESERVED(msrs, i)))
 			continue;
 		CTRL_READ(low, high, msrs, i);
@@ -175,31 +161,34 @@ static void op_amd_setup_ctrs(struct op_msrs const * const msrs)
 	}
 
 	/* avoid a false detection of ctr overflows in NMI handler */
-	for (i = 0; i < NUM_HARDWARE_COUNTERS; ++i) {
+	for (i = 0; i < NUM_COUNTERS; ++i) {
 		if (unlikely(!CTR_IS_RESERVED(msrs, i)))
 			continue;
 		CTR_WRITE(1, msrs, i);
 	}
 
 	/* enable active counters */
-	for (i = 0; i < NUM_HARDWARE_COUNTERS; ++i) {
-		int offset = i + __get_cpu_var(switch_index);
-		if ((counter_config[offset].enabled) && (CTR_IS_RESERVED(msrs, i))) {
-			CTR_WRITE(counter_config[offset].count, msrs, i);
+	for (i = 0; i < NUM_COUNTERS; ++i) {
+		if ((counter_config[i].enabled) && (CTR_IS_RESERVED(msrs, i))) {
+			reset_value[i] = counter_config[i].count;
+
+			CTR_WRITE(counter_config[i].count, msrs, i);
 
 			CTRL_READ(low, high, msrs, i);
 			CTRL_CLEAR_LO(low);
 			CTRL_CLEAR_HI(high);
 			CTRL_SET_ENABLE(low);
-			CTRL_SET_USR(low, counter_config[offset].user);
-			CTRL_SET_KERN(low, counter_config[offset].kernel);
-			CTRL_SET_UM(low, counter_config[offset].unit_mask);
-			CTRL_SET_EVENT_LOW(low, counter_config[offset].event);
-			CTRL_SET_EVENT_HIGH(high, counter_config[offset].event);
+			CTRL_SET_USR(low, counter_config[i].user);
+			CTRL_SET_KERN(low, counter_config[i].kernel);
+			CTRL_SET_UM(low, counter_config[i].unit_mask);
+			CTRL_SET_EVENT_LOW(low, counter_config[i].event);
+			CTRL_SET_EVENT_HIGH(high, counter_config[i].event);
 			CTRL_SET_HOST_ONLY(high, 0);
 			CTRL_SET_GUEST_ONLY(high, 0);
 
 			CTRL_WRITE(low, high, msrs, i);
+		} else {
+			reset_value[i] = 0;
 		}
 	}
 }
@@ -287,14 +276,13 @@ static int op_amd_check_ctrs(struct pt_regs * const regs,
 	unsigned int low, high;
 	int i;
 
-	for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
-		int offset = i + __get_cpu_var(switch_index);
-		if (!reset_value[offset])
+	for (i = 0 ; i < NUM_COUNTERS; ++i) {
+		if (!reset_value[i])
 			continue;
 		CTR_READ(low, high, msrs, i);
 		if (CTR_OVERFLOWED(low)) {
-			oprofile_add_sample(regs, offset);
-			CTR_WRITE(reset_value[offset], msrs, i);
+			oprofile_add_sample(regs, i);
+			CTR_WRITE(reset_value[i], msrs, i);
 		}
 	}
 
@@ -310,10 +298,8 @@ static void op_amd_start(struct op_msrs const * const msrs)
 {
 	unsigned int low, high;
 	int i;
-
-	for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
-		int offset = i + __get_cpu_var(switch_index);
-		if (reset_value[offset]) {
+	for (i = 0 ; i < NUM_COUNTERS ; ++i) {
+		if (reset_value[i]) {
 			CTRL_READ(low, high, msrs, i);
 			CTRL_SET_ACTIVE(low);
 			CTRL_WRITE(low, high, msrs, i);
@@ -343,8 +329,8 @@ static void op_amd_stop(struct op_msrs const * const msrs)
 
 	/* Subtle: stop on all counters to avoid race with
 	 * setting our pm callback */
-	for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
-		if (!reset_value[i + per_cpu(switch_index, smp_processor_id())])
+	for (i = 0 ; i < NUM_COUNTERS ; ++i) {
+		if (!reset_value[i])
 			continue;
 		CTRL_READ(low, high, msrs, i);
 		CTRL_SET_INACTIVE(low);
@@ -370,11 +356,11 @@ static void op_amd_shutdown(struct op_msrs const * const msrs)
 {
 	int i;
 
-	for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
+	for (i = 0 ; i < NUM_COUNTERS ; ++i) {
 		if (CTR_IS_RESERVED(msrs, i))
 			release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
 	}
-	for (i = 0 ; i < NUM_HARDWARE_COUNTERS ; ++i) {
+	for (i = 0 ; i < NUM_CONTROLS ; ++i) {
 		if (CTRL_IS_RESERVED(msrs, i))
 			release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
 	}
@@ -548,8 +534,6 @@ struct op_x86_model_spec const op_amd_spec = {
 	.exit = op_amd_exit,
 	.num_counters = NUM_COUNTERS,
 	.num_controls = NUM_CONTROLS,
-	.num_hardware_counters = NUM_HARDWARE_COUNTERS,
-	.num_hardware_controls = NUM_HARDWARE_CONTROLS,
 	.fill_in_addresses = &op_amd_fill_in_addresses,
 	.setup_ctrs = &op_amd_setup_ctrs,
 	.check_ctrs = &op_amd_check_ctrs,

arch/x86/oprofile/op_model_p4.c

@@ -700,8 +700,6 @@ static void p4_shutdown(struct op_msrs const * const msrs)
 struct op_x86_model_spec const op_p4_ht2_spec = {
 	.num_counters = NUM_COUNTERS_HT2,
 	.num_controls = NUM_CONTROLS_HT2,
-	.num_hardware_counters = NUM_COUNTERS_HT2,
-	.num_hardware_controls = NUM_CONTROLS_HT2,
 	.fill_in_addresses = &p4_fill_in_addresses,
 	.setup_ctrs = &p4_setup_ctrs,
 	.check_ctrs = &p4_check_ctrs,
@@ -714,8 +712,6 @@ struct op_x86_model_spec const op_p4_ht2_spec = {
 struct op_x86_model_spec const op_p4_spec = {
 	.num_counters = NUM_COUNTERS_NON_HT,
 	.num_controls = NUM_CONTROLS_NON_HT,
-	.num_hardware_counters = NUM_COUNTERS_NON_HT,
-	.num_hardware_controls = NUM_CONTROLS_NON_HT,
 	.fill_in_addresses = &p4_fill_in_addresses,
 	.setup_ctrs = &p4_setup_ctrs,
 	.check_ctrs = &p4_check_ctrs,

arch/x86/oprofile/op_model_ppro.c

@@ -183,8 +183,6 @@ static void ppro_shutdown(struct op_msrs const * const msrs)
 struct op_x86_model_spec const op_ppro_spec = {
 	.num_counters = NUM_COUNTERS,
 	.num_controls = NUM_CONTROLS,
-	.num_hardware_counters = NUM_COUNTERS,
-	.num_hardware_controls = NUM_CONTROLS,
 	.fill_in_addresses = &ppro_fill_in_addresses,
 	.setup_ctrs = &ppro_setup_ctrs,
 	.check_ctrs = &ppro_check_ctrs,

arch/x86/oprofile/op_x86_model.h

@@ -19,7 +19,6 @@ struct op_saved_msr {
 struct op_msr {
 	unsigned long addr;
 	struct op_saved_msr saved;
-	struct op_saved_msr multiplex;
 };
 
 struct op_msrs {
@@ -35,8 +34,6 @@ struct pt_regs;
 struct op_x86_model_spec {
 	int (*init)(struct oprofile_operations *ops);
 	void (*exit)(void);
-	unsigned int const num_hardware_counters;
-	unsigned int const num_hardware_controls;
 	unsigned int const num_counters;
 	unsigned int const num_controls;
 	void (*fill_in_addresses)(struct op_msrs * const msrs);

drivers/oprofile/oprof.c

@@ -12,8 +12,6 @@
 #include <linux/init.h>
 #include <linux/oprofile.h>
 #include <linux/moduleparam.h>
-#include <linux/workqueue.h>
-#include <linux/time.h>
 #include <asm/mutex.h>
 
 #include "oprof.h"
@@ -21,18 +19,13 @@
 #include "cpu_buffer.h"
 #include "buffer_sync.h"
 #include "oprofile_stats.h"
-
-static unsigned long is_setup;
-static void switch_worker(struct work_struct *work);
-static DECLARE_DELAYED_WORK(switch_work, switch_worker);
-static DEFINE_MUTEX(start_mutex);
  
 struct oprofile_operations oprofile_ops;
 
-unsigned long timeout_jiffies;
 unsigned long oprofile_started;
 unsigned long backtrace_depth;
-/* Multiplexing defaults at 1 msec*/
+static unsigned long is_setup;
+static DEFINE_MUTEX(start_mutex);
 
 /* timer
    0 - use performance monitoring hardware if available
@@ -94,16 +87,6 @@ int oprofile_setup(void)
 	return err;
 }
 
-static void start_switch_worker(void)
-{
-	schedule_delayed_work(&switch_work, timeout_jiffies);
-}
-
-static void switch_worker(struct work_struct *work)
-{
-	if (!oprofile_ops.switch_events())
-		start_switch_worker();
-}
 
 /* Actually start profiling (echo 1>/dev/oprofile/enable) */
 int oprofile_start(void)
@@ -111,6 +94,7 @@ int oprofile_start(void)
 	int err = -EINVAL;
  
 	mutex_lock(&start_mutex);
+ 
 	if (!is_setup)
 		goto out;
 
@@ -124,9 +108,6 @@ int oprofile_start(void)
 	if ((err = oprofile_ops.start()))
 		goto out;
 
-	if (oprofile_ops.switch_events)
-		start_switch_worker();
-
 	oprofile_started = 1;
 out:
 	mutex_unlock(&start_mutex);
@@ -142,7 +123,6 @@ void oprofile_stop(void)
 		goto out;
 	oprofile_ops.stop();
 	oprofile_started = 0;
-	cancel_delayed_work_sync(&switch_work);
 	/* wake up the daemon to read what remains */
 	wake_up_buffer_waiter();
 out:
@@ -175,32 +155,6 @@ void oprofile_shutdown(void)
 	mutex_unlock(&start_mutex);
 }
 
-/* User inputs in ms, converts to jiffies */
-int oprofile_set_timeout(unsigned long val_msec)
-{
-	int err = 0;
-
-	mutex_lock(&start_mutex);
-
-	if (oprofile_started) {
-		err = -EBUSY;
-		goto out;
-	}
-
-	if (!oprofile_ops.switch_events) {
-		err = -EINVAL;
-		goto out;
-	}
-
-	timeout_jiffies = msecs_to_jiffies(val_msec);
-	if (timeout_jiffies == MAX_JIFFY_OFFSET)
-		timeout_jiffies = msecs_to_jiffies(1);
-
-out:
-	mutex_unlock(&start_mutex);
-	return err;
-
-}
 
 int oprofile_set_backtrace(unsigned long val)
 {
@@ -225,16 +179,10 @@ int oprofile_set_backtrace(unsigned long val)
 	return err;
 }
 
-static void __init oprofile_switch_timer_init(void)
-{
-	timeout_jiffies = msecs_to_jiffies(1);
-}
-
 static int __init oprofile_init(void)
 {
 	int err;
 
-	oprofile_switch_timer_init();
 	err = oprofile_arch_init(&oprofile_ops);
 
 	if (err < 0 || timer) {

drivers/oprofile/oprof.h

@@ -27,8 +27,7 @@ extern unsigned long fs_buffer_watershed;
 extern struct oprofile_operations oprofile_ops;
 extern unsigned long oprofile_started;
 extern unsigned long backtrace_depth;
-extern unsigned long timeout_jiffies;
-
+ 
 struct super_block;
 struct dentry;
 
@@ -36,6 +35,5 @@ void oprofile_create_files(struct super_block * sb, struct dentry * root);
 void oprofile_timer_init(struct oprofile_operations * ops);
 
 int oprofile_set_backtrace(unsigned long depth);
-int oprofile_set_timeout(unsigned long time);
  
 #endif /* OPROF_H */

drivers/oprofile/oprofile_files.c

@@ -9,7 +9,6 @@
 
 #include <linux/fs.h>
 #include <linux/oprofile.h>
-#include <linux/jiffies.h>
 
 #include "event_buffer.h"
 #include "oprofile_stats.h"
@@ -19,40 +18,6 @@ unsigned long fs_buffer_size = 131072;
 unsigned long fs_cpu_buffer_size = 8192;
 unsigned long fs_buffer_watershed = 32768; /* FIXME: tune */
 
-static ssize_t timeout_read(struct file *file, char __user *buf,
-		size_t count, loff_t *offset)
-{
-	return oprofilefs_ulong_to_user(jiffies_to_msecs(timeout_jiffies),
-				buf, count, offset);
-}
-
-
-static ssize_t timeout_write(struct file *file, char const __user *buf,
-		size_t count, loff_t *offset)
-{
-	unsigned long val;
-	int retval;
-
-	if (*offset)
-		return -EINVAL;
-
-	retval = oprofilefs_ulong_from_user(&val, buf, count);
-	if (retval)
-		return retval;
-
-	retval = oprofile_set_timeout(val);
-
-	if (retval)
-		return retval;
-	return count;
-}
-
-static const struct file_operations timeout_fops = {
-	.read		= timeout_read,
-	.write		= timeout_write,
-};
-
-
 static ssize_t depth_read(struct file * file, char __user * buf, size_t count, loff_t * offset)
 {
 	return oprofilefs_ulong_to_user(backtrace_depth, buf, count, offset);
@@ -120,10 +85,11 @@ static ssize_t enable_write(struct file * file, char const __user * buf, size_t
 
 	if (*offset)
 		return -EINVAL;
+
 	retval = oprofilefs_ulong_from_user(&val, buf, count);
 	if (retval)
 		return retval;
-
+ 
 	if (val)
 		retval = oprofile_start();
 	else
@@ -163,7 +129,6 @@ void oprofile_create_files(struct super_block * sb, struct dentry * root)
 	oprofilefs_create_file(sb, root, "cpu_type", &cpu_type_fops); 
 	oprofilefs_create_file(sb, root, "backtrace_depth", &depth_fops);
 	oprofilefs_create_file(sb, root, "pointer_size", &pointer_size_fops);
-	oprofilefs_create_file(sb, root, "timeout_ms", &timeout_fops);
 	oprofile_create_stats_files(sb, root);
 	if (oprofile_ops.create_files)
 		oprofile_ops.create_files(sb, root);

include/linux/oprofile.h

@@ -67,9 +67,6 @@ struct oprofile_operations {
 
 	/* Initiate a stack backtrace. Optional. */
 	void (*backtrace)(struct pt_regs * const regs, unsigned int depth);
-
-	/* Multiplex between different events. Optional. */
-	int (*switch_events)(void);
 	/* CPU identification string. */
 	char * cpu_type;
 };