Merge branch 'tip/perf/core-2' of...

Merge branch 'tip/perf/core-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/core

arch/x86/kernel/stacktrace.c

@@ -66,7 +66,7 @@ void save_stack_trace(struct stack_trace *trace)
 }
 EXPORT_SYMBOL_GPL(save_stack_trace);
 
-void save_stack_trace_regs(struct stack_trace *trace, struct pt_regs *regs)
+void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 {
 	dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
 	if (trace->nr_entries < trace->max_entries)

arch/x86/mm/kmemcheck/error.c

@@ -185,7 +185,7 @@ void kmemcheck_error_save(enum kmemcheck_shadow state,
 	e->trace.entries = e->trace_entries;
 	e->trace.max_entries = ARRAY_SIZE(e->trace_entries);
 	e->trace.skip = 0;
-	save_stack_trace_regs(&e->trace, regs);
+	save_stack_trace_regs(regs, &e->trace);
 
 	/* Round address down to nearest 16 bytes */
 	shadow_copy = kmemcheck_shadow_lookup(address

include/linux/ftrace_event.h

@@ -129,6 +129,10 @@ void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
 void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
 				       struct ring_buffer_event *event,
 					unsigned long flags, int pc);
+void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
+					    struct ring_buffer_event *event,
+					    unsigned long flags, int pc,
+					    struct pt_regs *regs);
 void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
 					 struct ring_buffer_event *event);
 

include/linux/ring_buffer.h

@@ -169,7 +169,7 @@ void ring_buffer_set_clock(struct ring_buffer *buffer,
 size_t ring_buffer_page_len(void *page);
 
 
-void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
+void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
 void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 			  size_t len, int cpu, int full);

include/linux/stacktrace.h

@@ -14,8 +14,8 @@ struct stack_trace {
 };
 
 extern void save_stack_trace(struct stack_trace *trace);
-extern void save_stack_trace_regs(struct stack_trace *trace,
-				  struct pt_regs *regs);
+extern void save_stack_trace_regs(struct pt_regs *regs,
+				  struct stack_trace *trace);
 extern void save_stack_trace_tsk(struct task_struct *tsk,
 				struct stack_trace *trace);
 

kernel/async.c

@@ -49,12 +49,13 @@ asynchronous and synchronous parts of the kernel.
 */
 
 #include <linux/async.h>
+#include <linux/atomic.h>
+#include <linux/ktime.h>
 #include <linux/module.h>
 #include <linux/wait.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
-#include <asm/atomic.h>
 
 static async_cookie_t next_cookie = 1;
 
@@ -128,7 +129,8 @@ static void async_run_entry_fn(struct work_struct *work)
 
 	/* 2) run (and print duration) */
 	if (initcall_debug && system_state == SYSTEM_BOOTING) {
-		printk("calling  %lli_%pF @ %i\n", (long long)entry->cookie,
+		printk(KERN_DEBUG "calling  %lli_%pF @ %i\n",
+			(long long)entry->cookie,
 			entry->func, task_pid_nr(current));
 		calltime = ktime_get();
 	}
@@ -136,7 +138,7 @@ static void async_run_entry_fn(struct work_struct *work)
 	if (initcall_debug && system_state == SYSTEM_BOOTING) {
 		rettime = ktime_get();
 		delta = ktime_sub(rettime, calltime);
-		printk("initcall %lli_%pF returned 0 after %lld usecs\n",
+		printk(KERN_DEBUG "initcall %lli_%pF returned 0 after %lld usecs\n",
 			(long long)entry->cookie,
 			entry->func,
 			(long long)ktime_to_ns(delta) >> 10);
@@ -270,7 +272,7 @@ void async_synchronize_cookie_domain(async_cookie_t cookie,
 	ktime_t starttime, delta, endtime;
 
 	if (initcall_debug && system_state == SYSTEM_BOOTING) {
-		printk("async_waiting @ %i\n", task_pid_nr(current));
+		printk(KERN_DEBUG "async_waiting @ %i\n", task_pid_nr(current));
 		starttime = ktime_get();
 	}
 
@@ -280,7 +282,7 @@ void async_synchronize_cookie_domain(async_cookie_t cookie,
 		endtime = ktime_get();
 		delta = ktime_sub(endtime, starttime);
 
-		printk("async_continuing @ %i after %lli usec\n",
+		printk(KERN_DEBUG "async_continuing @ %i after %lli usec\n",
 			task_pid_nr(current),
 			(long long)ktime_to_ns(delta) >> 10);
 	}

kernel/stacktrace.c

@@ -26,12 +26,18 @@ void print_stack_trace(struct stack_trace *trace, int spaces)
 EXPORT_SYMBOL_GPL(print_stack_trace);
 
 /*
- * Architectures that do not implement save_stack_trace_tsk get this
- * weak alias and a once-per-bootup warning (whenever this facility
- * is utilized - for example by procfs):
+ * Architectures that do not implement save_stack_trace_tsk or
+ * save_stack_trace_regs get this weak alias and a once-per-bootup warning
+ * (whenever this facility is utilized - for example by procfs):
  */
 __weak void
 save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
 	WARN_ONCE(1, KERN_INFO "save_stack_trace_tsk() not implemented yet.\n");
 }
+
+__weak void
+save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
+{
+	WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
+}

kernel/trace/ftrace.c

@@ -32,7 +32,6 @@
 
 #include <trace/events/sched.h>
 
-#include <asm/ftrace.h>
 #include <asm/setup.h>
 
 #include "trace_output.h"
@@ -82,8 +81,7 @@ static int ftrace_disabled __read_mostly;
 
 static DEFINE_MUTEX(ftrace_lock);
 
-static struct ftrace_ops ftrace_list_end __read_mostly =
-{
+static struct ftrace_ops ftrace_list_end __read_mostly = {
 	.func		= ftrace_stub,
 };
 
@@ -785,8 +783,7 @@ static void unregister_ftrace_profiler(void)
 	unregister_ftrace_graph();
 }
 #else
-static struct ftrace_ops ftrace_profile_ops __read_mostly =
-{
+static struct ftrace_ops ftrace_profile_ops __read_mostly = {
 	.func		= function_profile_call,
 };
 
@@ -806,19 +803,10 @@ ftrace_profile_write(struct file *filp, const char __user *ubuf,
 		     size_t cnt, loff_t *ppos)
 {
 	unsigned long val;
-	char buf[64];		/* big enough to hold a number */
 	int ret;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	val = !!val;

kernel/trace/ring_buffer.c

@@ -997,15 +997,21 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
 			     unsigned nr_pages)
 {
 	struct buffer_page *bpage, *tmp;
-	unsigned long addr;
 	LIST_HEAD(pages);
 	unsigned i;
 
 	WARN_ON(!nr_pages);
 
 	for (i = 0; i < nr_pages; i++) {
+		struct page *page;
+		/*
+		 * __GFP_NORETRY flag makes sure that the allocation fails
+		 * gracefully without invoking oom-killer and the system is
+		 * not destabilized.
+		 */
 		bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
-				    GFP_KERNEL, cpu_to_node(cpu_buffer->cpu));
+				    GFP_KERNEL | __GFP_NORETRY,
+				    cpu_to_node(cpu_buffer->cpu));
 		if (!bpage)
 			goto free_pages;
 
@@ -1013,10 +1019,11 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
 
 		list_add(&bpage->list, &pages);
 
-		addr = __get_free_page(GFP_KERNEL);
-		if (!addr)
+		page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu),
+					GFP_KERNEL | __GFP_NORETRY, 0);
+		if (!page)
 			goto free_pages;
-		bpage->page = (void *)addr;
+		bpage->page = page_address(page);
 		rb_init_page(bpage->page);
 	}
 
@@ -1045,7 +1052,7 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
 {
 	struct ring_buffer_per_cpu *cpu_buffer;
 	struct buffer_page *bpage;
-	unsigned long addr;
+	struct page *page;
 	int ret;
 
 	cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()),
@@ -1067,10 +1074,10 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
 	rb_check_bpage(cpu_buffer, bpage);
 
 	cpu_buffer->reader_page = bpage;
-	addr = __get_free_page(GFP_KERNEL);
-	if (!addr)
+	page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, 0);
+	if (!page)
 		goto fail_free_reader;
-	bpage->page = (void *)addr;
+	bpage->page = page_address(page);
 	rb_init_page(bpage->page);
 
 	INIT_LIST_HEAD(&cpu_buffer->reader_page->list);
@@ -1314,7 +1321,6 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
 	unsigned nr_pages, rm_pages, new_pages;
 	struct buffer_page *bpage, *tmp;
 	unsigned long buffer_size;
-	unsigned long addr;
 	LIST_HEAD(pages);
 	int i, cpu;
 
@@ -1375,16 +1381,24 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
 
 	for_each_buffer_cpu(buffer, cpu) {
 		for (i = 0; i < new_pages; i++) {
+			struct page *page;
+			/*
+			 * __GFP_NORETRY flag makes sure that the allocation
+			 * fails gracefully without invoking oom-killer and
+			 * the system is not destabilized.
+			 */
 			bpage = kzalloc_node(ALIGN(sizeof(*bpage),
 						  cache_line_size()),
-					    GFP_KERNEL, cpu_to_node(cpu));
+					    GFP_KERNEL | __GFP_NORETRY,
+					    cpu_to_node(cpu));
 			if (!bpage)
 				goto free_pages;
 			list_add(&bpage->list, &pages);
-			addr = __get_free_page(GFP_KERNEL);
-			if (!addr)
+			page = alloc_pages_node(cpu_to_node(cpu),
+						GFP_KERNEL | __GFP_NORETRY, 0);
+			if (!page)
 				goto free_pages;
-			bpage->page = (void *)addr;
+			bpage->page = page_address(page);
 			rb_init_page(bpage->page);
 		}
 	}
@@ -3730,16 +3744,17 @@ EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu);
  * Returns:
  *  The page allocated, or NULL on error.
  */
-void *ring_buffer_alloc_read_page(struct ring_buffer *buffer)
+void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu)
 {
 	struct buffer_data_page *bpage;
-	unsigned long addr;
+	struct page *page;
 
-	addr = __get_free_page(GFP_KERNEL);
-	if (!addr)
+	page = alloc_pages_node(cpu_to_node(cpu),
+				GFP_KERNEL | __GFP_NORETRY, 0);
+	if (!page)
 		return NULL;
 
-	bpage = (void *)addr;
+	bpage = page_address(page);
 
 	rb_init_page(bpage);
 
@@ -3978,20 +3993,11 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
 		size_t cnt, loff_t *ppos)
 {
 	unsigned long *p = filp->private_data;
-	char buf[64];
 	unsigned long val;
 	int ret;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	if (val)

kernel/trace/ring_buffer_benchmark.c

@@ -106,7 +106,7 @@ static enum event_status read_page(int cpu)
 	int inc;
 	int i;
 
-	bpage = ring_buffer_alloc_read_page(buffer);
+	bpage = ring_buffer_alloc_read_page(buffer, cpu);
 	if (!bpage)
 		return EVENT_DROPPED;
 

kernel/trace/trace.c

@@ -343,26 +343,27 @@ unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
 static int trace_stop_count;
 static DEFINE_SPINLOCK(tracing_start_lock);
 
+static void wakeup_work_handler(struct work_struct *work)
+{
+	wake_up(&trace_wait);
+}
+
+static DECLARE_DELAYED_WORK(wakeup_work, wakeup_work_handler);
+
 /**
  * trace_wake_up - wake up tasks waiting for trace input
  *
- * Simply wakes up any task that is blocked on the trace_wait
- * queue. These is used with trace_poll for tasks polling the trace.
+ * Schedules a delayed work to wake up any task that is blocked on the
+ * trace_wait queue. These is used with trace_poll for tasks polling the
+ * trace.
  */
 void trace_wake_up(void)
 {
-	int cpu;
+	const unsigned long delay = msecs_to_jiffies(2);
 
 	if (trace_flags & TRACE_ITER_BLOCK)
 		return;
-	/*
-	 * The runqueue_is_locked() can fail, but this is the best we
-	 * have for now:
-	 */
-	cpu = get_cpu();
-	if (!runqueue_is_locked(cpu))
-		wake_up(&trace_wait);
-	put_cpu();
+	schedule_delayed_work(&wakeup_work, delay);
 }
 
 static int __init set_buf_size(char *str)
@@ -424,6 +425,7 @@ static const char *trace_options[] = {
 	"graph-time",
 	"record-cmd",
 	"overwrite",
+	"disable_on_free",
 	NULL
 };
 
@@ -1191,6 +1193,18 @@ void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
 }
 EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
 
+void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
+					    struct ring_buffer_event *event,
+					    unsigned long flags, int pc,
+					    struct pt_regs *regs)
+{
+	ring_buffer_unlock_commit(buffer, event);
+
+	ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
+	ftrace_trace_userstack(buffer, flags, pc);
+}
+EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit_regs);
+
 void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
 					 struct ring_buffer_event *event)
 {
@@ -1236,7 +1250,7 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data,
 #ifdef CONFIG_STACKTRACE
 static void __ftrace_trace_stack(struct ring_buffer *buffer,
 				 unsigned long flags,
-				 int skip, int pc)
+				 int skip, int pc, struct pt_regs *regs)
 {
 	struct ftrace_event_call *call = &event_kernel_stack;
 	struct ring_buffer_event *event;
@@ -1255,24 +1269,36 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
 	trace.skip		= skip;
 	trace.entries		= entry->caller;
 
-	save_stack_trace(&trace);
+	if (regs)
+		save_stack_trace_regs(regs, &trace);
+	else
+		save_stack_trace(&trace);
 	if (!filter_check_discard(call, entry, buffer, event))
 		ring_buffer_unlock_commit(buffer, event);
 }
 
+void ftrace_trace_stack_regs(struct ring_buffer *buffer, unsigned long flags,
+			     int skip, int pc, struct pt_regs *regs)
+{
+	if (!(trace_flags & TRACE_ITER_STACKTRACE))
+		return;
+
+	__ftrace_trace_stack(buffer, flags, skip, pc, regs);
+}
+
 void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
 			int skip, int pc)
 {
 	if (!(trace_flags & TRACE_ITER_STACKTRACE))
 		return;
 
-	__ftrace_trace_stack(buffer, flags, skip, pc);
+	__ftrace_trace_stack(buffer, flags, skip, pc, NULL);
 }
 
 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
 		   int pc)
 {
-	__ftrace_trace_stack(tr->buffer, flags, skip, pc);
+	__ftrace_trace_stack(tr->buffer, flags, skip, pc, NULL);
 }
 
 /**
@@ -1288,7 +1314,7 @@ void trace_dump_stack(void)
 	local_save_flags(flags);
 
 	/* skipping 3 traces, seems to get us at the caller of this function */
-	__ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count());
+	__ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count(), NULL);
 }
 
 static DEFINE_PER_CPU(int, user_stack_count);
@@ -2051,6 +2077,9 @@ void trace_default_header(struct seq_file *m)
 {
 	struct trace_iterator *iter = m->private;
 
+	if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
+		return;
+
 	if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
 		/* print nothing if the buffers are empty */
 		if (trace_empty(iter))
@@ -2701,20 +2730,11 @@ tracing_ctrl_write(struct file *filp, const char __user *ubuf,
 		   size_t cnt, loff_t *ppos)
 {
 	struct trace_array *tr = filp->private_data;
-	char buf[64];
 	unsigned long val;
 	int ret;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	val = !!val;
@@ -2767,7 +2787,7 @@ int tracer_init(struct tracer *t, struct trace_array *tr)
 	return t->init(tr);
 }
 
-static int tracing_resize_ring_buffer(unsigned long size)
+static int __tracing_resize_ring_buffer(unsigned long size)
 {
 	int ret;
 
@@ -2819,6 +2839,41 @@ static int tracing_resize_ring_buffer(unsigned long size)
 	return ret;
 }
 
+static ssize_t tracing_resize_ring_buffer(unsigned long size)
+{
+	int cpu, ret = size;
+
+	mutex_lock(&trace_types_lock);
+
+	tracing_stop();
+
+	/* disable all cpu buffers */
+	for_each_tracing_cpu(cpu) {
+		if (global_trace.data[cpu])
+			atomic_inc(&global_trace.data[cpu]->disabled);
+		if (max_tr.data[cpu])
+			atomic_inc(&max_tr.data[cpu]->disabled);
+	}
+
+	if (size != global_trace.entries)
+		ret = __tracing_resize_ring_buffer(size);
+
+	if (ret < 0)
+		ret = -ENOMEM;
+
+	for_each_tracing_cpu(cpu) {
+		if (global_trace.data[cpu])
+			atomic_dec(&global_trace.data[cpu]->disabled);
+		if (max_tr.data[cpu])
+			atomic_dec(&max_tr.data[cpu]->disabled);
+	}
+
+	tracing_start();
+	mutex_unlock(&trace_types_lock);
+
+	return ret;
+}
+
 
 /**
  * tracing_update_buffers - used by tracing facility to expand ring buffers
@@ -2836,7 +2891,7 @@ int tracing_update_buffers(void)
 
 	mutex_lock(&trace_types_lock);
 	if (!ring_buffer_expanded)
-		ret = tracing_resize_ring_buffer(trace_buf_size);
+		ret = __tracing_resize_ring_buffer(trace_buf_size);
 	mutex_unlock(&trace_types_lock);
 
 	return ret;
@@ -2860,7 +2915,7 @@ static int tracing_set_tracer(const char *buf)
 	mutex_lock(&trace_types_lock);
 
 	if (!ring_buffer_expanded) {
-		ret = tracing_resize_ring_buffer(trace_buf_size);
+		ret = __tracing_resize_ring_buffer(trace_buf_size);
 		if (ret < 0)
 			goto out;
 		ret = 0;
@@ -2966,20 +3021,11 @@ tracing_max_lat_write(struct file *filp, const char __user *ubuf,
 		      size_t cnt, loff_t *ppos)
 {
 	unsigned long *ptr = filp->private_data;
-	char buf[64];
 	unsigned long val;
 	int ret;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	*ptr = val * 1000;
@@ -3434,67 +3480,54 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
 		      size_t cnt, loff_t *ppos)
 {
 	unsigned long val;
-	char buf[64];
-	int ret, cpu;
-
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
+	int ret;
 
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	/* must have at least 1 entry */
 	if (!val)
 		return -EINVAL;
 
-	mutex_lock(&trace_types_lock);
-
-	tracing_stop();
-
-	/* disable all cpu buffers */
-	for_each_tracing_cpu(cpu) {
-		if (global_trace.data[cpu])
-			atomic_inc(&global_trace.data[cpu]->disabled);
-		if (max_tr.data[cpu])
-			atomic_inc(&max_tr.data[cpu]->disabled);
-	}
-
 	/* value is in KB */
 	val <<= 10;
 
-	if (val != global_trace.entries) {
-		ret = tracing_resize_ring_buffer(val);
-		if (ret < 0) {
-			cnt = ret;
-			goto out;
-		}
-	}
+	ret = tracing_resize_ring_buffer(val);
+	if (ret < 0)
+		return ret;
 
 	*ppos += cnt;
 
-	/* If check pages failed, return ENOMEM */
-	if (tracing_disabled)
-		cnt = -ENOMEM;
- out:
-	for_each_tracing_cpu(cpu) {
-		if (global_trace.data[cpu])
-			atomic_dec(&global_trace.data[cpu]->disabled);
-		if (max_tr.data[cpu])
-			atomic_dec(&max_tr.data[cpu]->disabled);
-	}
+	return cnt;
+}
 
-	tracing_start();
-	mutex_unlock(&trace_types_lock);
+static ssize_t
+tracing_free_buffer_write(struct file *filp, const char __user *ubuf,
+			  size_t cnt, loff_t *ppos)
+{
+	/*
+	 * There is no need to read what the user has written, this function
+	 * is just to make sure that there is no error when "echo" is used
+	 */
+
+	*ppos += cnt;
 
 	return cnt;
 }
 
+static int
+tracing_free_buffer_release(struct inode *inode, struct file *filp)
+{
+	/* disable tracing ? */
+	if (trace_flags & TRACE_ITER_STOP_ON_FREE)
+		tracing_off();
+	/* resize the ring buffer to 0 */
+	tracing_resize_ring_buffer(0);
+
+	return 0;
+}
+
 static int mark_printk(const char *fmt, ...)
 {
 	int ret;
@@ -3640,6 +3673,11 @@ static const struct file_operations tracing_entries_fops = {
 	.llseek		= generic_file_llseek,
 };
 
+static const struct file_operations tracing_free_buffer_fops = {
+	.write		= tracing_free_buffer_write,
+	.release	= tracing_free_buffer_release,
+};
+
 static const struct file_operations tracing_mark_fops = {
 	.open		= tracing_open_generic,
 	.write		= tracing_mark_write,
@@ -3696,7 +3734,7 @@ tracing_buffers_read(struct file *filp, char __user *ubuf,
 		return 0;
 
 	if (!info->spare)
-		info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
+		info->spare = ring_buffer_alloc_read_page(info->tr->buffer, info->cpu);
 	if (!info->spare)
 		return -ENOMEM;
 
@@ -3853,7 +3891,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 
 		ref->ref = 1;
 		ref->buffer = info->tr->buffer;
-		ref->page = ring_buffer_alloc_read_page(ref->buffer);
+		ref->page = ring_buffer_alloc_read_page(ref->buffer, info->cpu);
 		if (!ref->page) {
 			kfree(ref);
 			break;
@@ -3862,8 +3900,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 		r = ring_buffer_read_page(ref->buffer, &ref->page,
 					  len, info->cpu, 1);
 		if (r < 0) {
-			ring_buffer_free_read_page(ref->buffer,
-						   ref->page);
+			ring_buffer_free_read_page(ref->buffer, ref->page);
 			kfree(ref);
 			break;
 		}
@@ -4099,19 +4136,10 @@ trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
 {
 	struct trace_option_dentry *topt = filp->private_data;
 	unsigned long val;
-	char buf[64];
 	int ret;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	if (val != 0 && val != 1)
@@ -4159,20 +4187,11 @@ trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
 			 loff_t *ppos)
 {
 	long index = (long)filp->private_data;
-	char buf[64];
 	unsigned long val;
 	int ret;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	if (val != 0 && val != 1)
@@ -4365,6 +4384,9 @@ static __init int tracer_init_debugfs(void)
 	trace_create_file("buffer_size_kb", 0644, d_tracer,
 			&global_trace, &tracing_entries_fops);
 
+	trace_create_file("free_buffer", 0644, d_tracer,
+			&global_trace, &tracing_free_buffer_fops);
+
 	trace_create_file("trace_marker", 0220, d_tracer,
 			NULL, &tracing_mark_fops);
 

kernel/trace/trace.h

@@ -389,6 +389,9 @@ void update_max_tr_single(struct trace_array *tr,
 void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
 			int skip, int pc);
 
+void ftrace_trace_stack_regs(struct ring_buffer *buffer, unsigned long flags,
+			     int skip, int pc, struct pt_regs *regs);
+
 void ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags,
 			    int pc);
 
@@ -400,6 +403,12 @@ static inline void ftrace_trace_stack(struct ring_buffer *buffer,
 {
 }
 
+static inline void ftrace_trace_stack_regs(struct ring_buffer *buffer,
+					   unsigned long flags, int skip,
+					   int pc, struct pt_regs *regs)
+{
+}
+
 static inline void ftrace_trace_userstack(struct ring_buffer *buffer,
 					  unsigned long flags, int pc)
 {
@@ -609,6 +618,7 @@ enum trace_iterator_flags {
 	TRACE_ITER_GRAPH_TIME		= 0x80000,
 	TRACE_ITER_RECORD_CMD		= 0x100000,
 	TRACE_ITER_OVERWRITE		= 0x200000,
+	TRACE_ITER_STOP_ON_FREE		= 0x400000,
 };
 
 /*

kernel/trace/trace_events.c

@@ -486,20 +486,11 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 		   loff_t *ppos)
 {
 	struct ftrace_event_call *call = filp->private_data;
-	char buf[64];
 	unsigned long val;
 	int ret;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	ret = tracing_update_buffers();
@@ -571,19 +562,10 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 {
 	const char *system = filp->private_data;
 	unsigned long val;
-	char buf[64];
 	ssize_t ret;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+	if (ret)
 		return ret;
 
 	ret = tracing_update_buffers();

kernel/trace/trace_functions_graph.c

@@ -74,6 +74,20 @@ static struct tracer_flags tracer_flags = {
 
 static struct trace_array *graph_array;
 
+/*
+ * DURATION column is being also used to display IRQ signs,
+ * following values are used by print_graph_irq and others
+ * to fill in space into DURATION column.
+ */
+enum {
+	DURATION_FILL_FULL  = -1,
+	DURATION_FILL_START = -2,
+	DURATION_FILL_END   = -3,
+};
+
+static enum print_line_t
+print_graph_duration(unsigned long long duration, struct trace_seq *s,
+		     u32 flags);
 
 /* Add a function return address to the trace stack on thread info.*/
 int
@@ -577,32 +591,6 @@ get_return_for_leaf(struct trace_iterator *iter,
 	return next;
 }
 
-/* Signal a overhead of time execution to the output */
-static int
-print_graph_overhead(unsigned long long duration, struct trace_seq *s,
-		     u32 flags)
-{
-	/* If duration disappear, we don't need anything */
-	if (!(flags & TRACE_GRAPH_PRINT_DURATION))
-		return 1;
-
-	/* Non nested entry or return */
-	if (duration == -1)
-		return trace_seq_printf(s, "  ");
-
-	if (flags & TRACE_GRAPH_PRINT_OVERHEAD) {
-		/* Duration exceeded 100 msecs */
-		if (duration > 100000ULL)
-			return trace_seq_printf(s, "! ");
-
-		/* Duration exceeded 10 msecs */
-		if (duration > 10000ULL)
-			return trace_seq_printf(s, "+ ");
-	}
-
-	return trace_seq_printf(s, "  ");
-}
-
 static int print_graph_abs_time(u64 t, struct trace_seq *s)
 {
 	unsigned long usecs_rem;
@@ -625,34 +613,36 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 		addr >= (unsigned long)__irqentry_text_end)
 		return TRACE_TYPE_UNHANDLED;
 
-	/* Absolute time */
-	if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
-		ret = print_graph_abs_time(iter->ts, s);
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
+		/* Absolute time */
+		if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
+			ret = print_graph_abs_time(iter->ts, s);
+			if (!ret)
+				return TRACE_TYPE_PARTIAL_LINE;
+		}
 
-	/* Cpu */
-	if (flags & TRACE_GRAPH_PRINT_CPU) {
-		ret = print_graph_cpu(s, cpu);
-		if (ret == TRACE_TYPE_PARTIAL_LINE)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+		/* Cpu */
+		if (flags & TRACE_GRAPH_PRINT_CPU) {
+			ret = print_graph_cpu(s, cpu);
+			if (ret == TRACE_TYPE_PARTIAL_LINE)
+				return TRACE_TYPE_PARTIAL_LINE;
+		}
 
-	/* Proc */
-	if (flags & TRACE_GRAPH_PRINT_PROC) {
-		ret = print_graph_proc(s, pid);
-		if (ret == TRACE_TYPE_PARTIAL_LINE)
-			return TRACE_TYPE_PARTIAL_LINE;
-		ret = trace_seq_printf(s, " | ");
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
+		/* Proc */
+		if (flags & TRACE_GRAPH_PRINT_PROC) {
+			ret = print_graph_proc(s, pid);
+			if (ret == TRACE_TYPE_PARTIAL_LINE)
+				return TRACE_TYPE_PARTIAL_LINE;
+			ret = trace_seq_printf(s, " | ");
+			if (!ret)
+				return TRACE_TYPE_PARTIAL_LINE;
+		}
 	}
 
 	/* No overhead */
-	ret = print_graph_overhead(-1, s, flags);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
+	ret = print_graph_duration(DURATION_FILL_START, s, flags);
+	if (ret != TRACE_TYPE_HANDLED)
+		return ret;
 
 	if (type == TRACE_GRAPH_ENT)
 		ret = trace_seq_printf(s, "==========>");
@@ -662,9 +652,10 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
 	if (!ret)
 		return TRACE_TYPE_PARTIAL_LINE;
 
-	/* Don't close the duration column if haven't one */
-	if (flags & TRACE_GRAPH_PRINT_DURATION)
-		trace_seq_printf(s, " |");
+	ret = print_graph_duration(DURATION_FILL_END, s, flags);
+	if (ret != TRACE_TYPE_HANDLED)
+		return ret;
+
 	ret = trace_seq_printf(s, "\n");
 
 	if (!ret)
@@ -716,9 +707,49 @@ trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
 }
 
 static enum print_line_t
-print_graph_duration(unsigned long long duration, struct trace_seq *s)
+print_graph_duration(unsigned long long duration, struct trace_seq *s,
+		     u32 flags)
 {
-	int ret;
+	int ret = -1;
+
+	if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
+	    !(trace_flags & TRACE_ITER_CONTEXT_INFO))
+			return TRACE_TYPE_HANDLED;
+
+	/* No real adata, just filling the column with spaces */
+	switch (duration) {
+	case DURATION_FILL_FULL:
+		ret = trace_seq_printf(s, "              |  ");
+		return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
+	case DURATION_FILL_START:
+		ret = trace_seq_printf(s, "  ");
+		return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
+	case DURATION_FILL_END:
+		ret = trace_seq_printf(s, " |");
+		return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
+	}
+
+	/* Signal a overhead of time execution to the output */
+	if (flags & TRACE_GRAPH_PRINT_OVERHEAD) {
+		/* Duration exceeded 100 msecs */
+		if (duration > 100000ULL)
+			ret = trace_seq_printf(s, "! ");
+		/* Duration exceeded 10 msecs */
+		else if (duration > 10000ULL)
+			ret = trace_seq_printf(s, "+ ");
+	}
+
+	/*
+	 * The -1 means we either did not exceed the duration tresholds
+	 * or we dont want to print out the overhead. Either way we need
+	 * to fill out the space.
+	 */
+	if (ret == -1)
+		ret = trace_seq_printf(s, "  ");
+
+	/* Catching here any failure happenned above */
+	if (!ret)
+		return TRACE_TYPE_PARTIAL_LINE;
 
 	ret = trace_print_graph_duration(duration, s);
 	if (ret != TRACE_TYPE_HANDLED)
@@ -767,18 +798,11 @@ print_graph_entry_leaf(struct trace_iterator *iter,
 			cpu_data->enter_funcs[call->depth] = 0;
 	}
 
-	/* Overhead */
-	ret = print_graph_overhead(duration, s, flags);
-	if (!ret)
+	/* Overhead and duration */
+	ret = print_graph_duration(duration, s, flags);
+	if (ret == TRACE_TYPE_PARTIAL_LINE)
 		return TRACE_TYPE_PARTIAL_LINE;
 
-	/* Duration */
-	if (flags & TRACE_GRAPH_PRINT_DURATION) {
-		ret = print_graph_duration(duration, s);
-		if (ret == TRACE_TYPE_PARTIAL_LINE)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
-
 	/* Function */
 	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
 		ret = trace_seq_printf(s, " ");
@@ -815,17 +839,10 @@ print_graph_entry_nested(struct trace_iterator *iter,
 			cpu_data->enter_funcs[call->depth] = call->func;
 	}
 
-	/* No overhead */
-	ret = print_graph_overhead(-1, s, flags);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
 	/* No time */
-	if (flags & TRACE_GRAPH_PRINT_DURATION) {
-		ret = trace_seq_printf(s, "            |  ");
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	ret = print_graph_duration(DURATION_FILL_FULL, s, flags);
+	if (ret != TRACE_TYPE_HANDLED)
+		return ret;
 
 	/* Function */
 	for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
@@ -865,6 +882,9 @@ print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
 			return TRACE_TYPE_PARTIAL_LINE;
 	}
 
+	if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
+		return 0;
+
 	/* Absolute time */
 	if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
 		ret = print_graph_abs_time(iter->ts, s);
@@ -1078,18 +1098,11 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 	if (print_graph_prologue(iter, s, 0, 0, flags))
 		return TRACE_TYPE_PARTIAL_LINE;
 
-	/* Overhead */
-	ret = print_graph_overhead(duration, s, flags);
-	if (!ret)
+	/* Overhead and duration */
+	ret = print_graph_duration(duration, s, flags);
+	if (ret == TRACE_TYPE_PARTIAL_LINE)
 		return TRACE_TYPE_PARTIAL_LINE;
 
-	/* Duration */
-	if (flags & TRACE_GRAPH_PRINT_DURATION) {
-		ret = print_graph_duration(duration, s);
-		if (ret == TRACE_TYPE_PARTIAL_LINE)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
-
 	/* Closing brace */
 	for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
 		ret = trace_seq_printf(s, " ");
@@ -1146,17 +1159,10 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 	if (print_graph_prologue(iter, s, 0, 0, flags))
 		return TRACE_TYPE_PARTIAL_LINE;
 
-	/* No overhead */
-	ret = print_graph_overhead(-1, s, flags);
-	if (!ret)
-		return TRACE_TYPE_PARTIAL_LINE;
-
 	/* No time */
-	if (flags & TRACE_GRAPH_PRINT_DURATION) {
-		ret = trace_seq_printf(s, "            |  ");
-		if (!ret)
-			return TRACE_TYPE_PARTIAL_LINE;
-	}
+	ret = print_graph_duration(DURATION_FILL_FULL, s, flags);
+	if (ret != TRACE_TYPE_HANDLED)
+		return ret;
 
 	/* Indentation */
 	if (depth > 0)
@@ -1207,7 +1213,7 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 
 
 enum print_line_t
-__print_graph_function_flags(struct trace_iterator *iter, u32 flags)
+print_graph_function_flags(struct trace_iterator *iter, u32 flags)
 {
 	struct ftrace_graph_ent_entry *field;
 	struct fgraph_data *data = iter->private;
@@ -1270,18 +1276,7 @@ __print_graph_function_flags(struct trace_iterator *iter, u32 flags)
 static enum print_line_t
 print_graph_function(struct trace_iterator *iter)
 {
-	return __print_graph_function_flags(iter, tracer_flags.val);
-}
-
-enum print_line_t print_graph_function_flags(struct trace_iterator *iter,
-					     u32 flags)
-{
-	if (trace_flags & TRACE_ITER_LATENCY_FMT)
-		flags |= TRACE_GRAPH_PRINT_DURATION;
-	else
-		flags |= TRACE_GRAPH_PRINT_ABS_TIME;
-
-	return __print_graph_function_flags(iter, flags);
+	return print_graph_function_flags(iter, tracer_flags.val);
 }
 
 static enum print_line_t
@@ -1309,8 +1304,7 @@ static void print_lat_header(struct seq_file *s, u32 flags)
 	seq_printf(s, "#%.*s / _----=> need-resched    \n", size, spaces);
 	seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
 	seq_printf(s, "#%.*s|| / _--=> preempt-depth   \n", size, spaces);
-	seq_printf(s, "#%.*s||| / _-=> lock-depth      \n", size, spaces);
-	seq_printf(s, "#%.*s|||| /                     \n", size, spaces);
+	seq_printf(s, "#%.*s||| /                      \n", size, spaces);
 }
 
 static void __print_graph_headers_flags(struct seq_file *s, u32 flags)
@@ -1329,7 +1323,7 @@ static void __print_graph_headers_flags(struct seq_file *s, u32 flags)
 	if (flags & TRACE_GRAPH_PRINT_PROC)
 		seq_printf(s, "  TASK/PID       ");
 	if (lat)
-		seq_printf(s, "|||||");
+		seq_printf(s, "||||");
 	if (flags & TRACE_GRAPH_PRINT_DURATION)
 		seq_printf(s, "  DURATION   ");
 	seq_printf(s, "               FUNCTION CALLS\n");
@@ -1343,7 +1337,7 @@ static void __print_graph_headers_flags(struct seq_file *s, u32 flags)
 	if (flags & TRACE_GRAPH_PRINT_PROC)
 		seq_printf(s, "   |    |        ");
 	if (lat)
-		seq_printf(s, "|||||");
+		seq_printf(s, "||||");
 	if (flags & TRACE_GRAPH_PRINT_DURATION)
 		seq_printf(s, "   |   |      ");
 	seq_printf(s, "               |   |   |   |\n");
@@ -1358,15 +1352,16 @@ void print_graph_headers_flags(struct seq_file *s, u32 flags)
 {
 	struct trace_iterator *iter = s->private;
 
+	if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
+		return;
+
 	if (trace_flags & TRACE_ITER_LATENCY_FMT) {
 		/* print nothing if the buffers are empty */
 		if (trace_empty(iter))
 			return;
 
 		print_trace_header(s, iter);
-		flags |= TRACE_GRAPH_PRINT_DURATION;
-	} else
-		flags |= TRACE_GRAPH_PRINT_ABS_TIME;
+	}
 
 	__print_graph_headers_flags(s, flags);
 }

kernel/trace/trace_irqsoff.c

@@ -226,7 +226,9 @@ static void irqsoff_trace_close(struct trace_iterator *iter)
 }
 
 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
-			    TRACE_GRAPH_PRINT_PROC)
+			    TRACE_GRAPH_PRINT_PROC | \
+			    TRACE_GRAPH_PRINT_ABS_TIME | \
+			    TRACE_GRAPH_PRINT_DURATION)
 
 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
 {

kernel/trace/trace_kprobe.c

@@ -1397,7 +1397,8 @@ static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
 	store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
 	if (!filter_current_check_discard(buffer, call, entry, event))
-		trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
+		trace_nowake_buffer_unlock_commit_regs(buffer, event,
+						       irq_flags, pc, regs);
 }
 
 /* Kretprobe handler */
@@ -1429,7 +1430,8 @@ static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
 	store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
 	if (!filter_current_check_discard(buffer, call, entry, event))
-		trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
+		trace_nowake_buffer_unlock_commit_regs(buffer, event,
+						       irq_flags, pc, regs);
 }
 
 /* Event entry printers */

kernel/trace/trace_sched_wakeup.c

@@ -227,7 +227,9 @@ static void wakeup_trace_close(struct trace_iterator *iter)
 		graph_trace_close(iter);
 }
 
-#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC)
+#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
+			    TRACE_GRAPH_PRINT_ABS_TIME | \
+			    TRACE_GRAPH_PRINT_DURATION)
 
 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 {

kernel/trace/trace_stack.c

@@ -156,20 +156,11 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
 {
 	long *ptr = filp->private_data;
 	unsigned long val, flags;
-	char buf[64];
 	int ret;
 	int cpu;
 
-	if (count >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, count))
-		return -EFAULT;
-
-	buf[count] = 0;
-
-	ret = strict_strtoul(buf, 10, &val);
-	if (ret < 0)
+	ret = kstrtoul_from_user(ubuf, count, 10, &val);
+	if (ret)
 		return ret;
 
 	local_irq_save(flags);