Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace

include/linux/kernel.h

@@ -369,8 +369,35 @@ static inline char *pack_hex_byte(char *buf, u8 byte)
 
 /*
  * General tracing related utility functions - trace_printk(),
- * tracing_start()/tracing_stop:
+ * tracing_on/tracing_off and tracing_start()/tracing_stop
+ *
+ * Use tracing_on/tracing_off when you want to quickly turn on or off
+ * tracing. It simply enables or disables the recording of the trace events.
+ * This also corresponds to the user space debugfs/tracing/tracing_on
+ * file, which gives a means for the kernel and userspace to interact.
+ * Place a tracing_off() in the kernel where you want tracing to end.
+ * From user space, examine the trace, and then echo 1 > tracing_on
+ * to continue tracing.
+ *
+ * tracing_stop/tracing_start has slightly more overhead. It is used
+ * by things like suspend to ram where disabling the recording of the
+ * trace is not enough, but tracing must actually stop because things
+ * like calling smp_processor_id() may crash the system.
+ *
+ * Most likely, you want to use tracing_on/tracing_off.
  */
+#ifdef CONFIG_RING_BUFFER
+void tracing_on(void);
+void tracing_off(void);
+/* trace_off_permanent stops recording with no way to bring it back */
+void tracing_off_permanent(void);
+int tracing_is_on(void);
+#else
+static inline void tracing_on(void) { }
+static inline void tracing_off(void) { }
+static inline void tracing_off_permanent(void) { }
+static inline int tracing_is_on(void) { return 0; }
+#endif
 #ifdef CONFIG_TRACING
 extern void tracing_start(void);
 extern void tracing_stop(void);

include/linux/ring_buffer.h

@@ -124,21 +124,6 @@ void ring_buffer_normalize_time_stamp(int cpu, u64 *ts);
 size_t ring_buffer_page_len(void *page);
 
 
-/*
- * The below functions are fine to use outside the tracing facility.
- */
-#ifdef CONFIG_RING_BUFFER
-void tracing_on(void);
-void tracing_off(void);
-void tracing_off_permanent(void);
-int tracing_is_on(void);
-#else
-static inline void tracing_on(void) { }
-static inline void tracing_off(void) { }
-static inline void tracing_off_permanent(void) { }
-static inline int tracing_is_on(void) { return 0; }
-#endif
-
 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
 void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,

kernel/trace/Makefile

@@ -41,5 +41,6 @@ obj-$(CONFIG_WORKQUEUE_TRACER) += trace_workqueue.o
 obj-$(CONFIG_BLK_DEV_IO_TRACE)	+= blktrace.o
 obj-$(CONFIG_EVENT_TRACER) += trace_events.o
 obj-$(CONFIG_EVENT_TRACER) += events.o
+obj-$(CONFIG_EVENT_TRACER) += trace_export.o
 
 libftrace-y := ftrace.o

kernel/trace/ftrace.c

@@ -1869,21 +1869,21 @@ ftrace_notrace_release(struct inode *inode, struct file *file)
 	return ftrace_regex_release(inode, file, 0);
 }
 
-static struct file_operations ftrace_avail_fops = {
+static const struct file_operations ftrace_avail_fops = {
 	.open = ftrace_avail_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = ftrace_avail_release,
 };
 
-static struct file_operations ftrace_failures_fops = {
+static const struct file_operations ftrace_failures_fops = {
 	.open = ftrace_failures_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = ftrace_avail_release,
 };
 
-static struct file_operations ftrace_filter_fops = {
+static const struct file_operations ftrace_filter_fops = {
 	.open = ftrace_filter_open,
 	.read = ftrace_regex_read,
 	.write = ftrace_filter_write,
@@ -1891,7 +1891,7 @@ static struct file_operations ftrace_filter_fops = {
 	.release = ftrace_filter_release,
 };
 
-static struct file_operations ftrace_notrace_fops = {
+static const struct file_operations ftrace_notrace_fops = {
 	.open = ftrace_notrace_open,
 	.read = ftrace_regex_read,
 	.write = ftrace_notrace_write,
@@ -2423,7 +2423,7 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf,
 	return cnt;
 }
 
-static struct file_operations ftrace_pid_fops = {
+static const struct file_operations ftrace_pid_fops = {
 	.read = ftrace_pid_read,
 	.write = ftrace_pid_write,
 };

kernel/trace/ring_buffer.c

@@ -2606,7 +2606,7 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
 	return cnt;
 }
 
-static struct file_operations rb_simple_fops = {
+static const struct file_operations rb_simple_fops = {
 	.open		= tracing_open_generic,
 	.read		= rb_simple_read,
 	.write		= rb_simple_write,

kernel/trace/trace.c

@@ -1882,14 +1882,14 @@ static int show_traces_open(struct inode *inode, struct file *file)
 	return ret;
 }
 
-static struct file_operations tracing_fops = {
+static const struct file_operations tracing_fops = {
 	.open		= tracing_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
 	.release	= tracing_release,
 };
 
-static struct file_operations show_traces_fops = {
+static const struct file_operations show_traces_fops = {
 	.open		= show_traces_open,
 	.read		= seq_read,
 	.release	= seq_release,
@@ -1982,7 +1982,7 @@ err_unlock:
 	return err;
 }
 
-static struct file_operations tracing_cpumask_fops = {
+static const struct file_operations tracing_cpumask_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_cpumask_read,
 	.write		= tracing_cpumask_write,
@@ -2134,7 +2134,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 	return cnt;
 }
 
-static struct file_operations tracing_iter_fops = {
+static const struct file_operations tracing_iter_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_trace_options_read,
 	.write		= tracing_trace_options_write,
@@ -2167,7 +2167,7 @@ tracing_readme_read(struct file *filp, char __user *ubuf,
 					readme_msg, strlen(readme_msg));
 }
 
-static struct file_operations tracing_readme_fops = {
+static const struct file_operations tracing_readme_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_readme_read,
 };
@@ -2927,25 +2927,25 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	return cnt;
 }
 
-static struct file_operations tracing_max_lat_fops = {
+static const struct file_operations tracing_max_lat_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_max_lat_read,
 	.write		= tracing_max_lat_write,
 };
 
-static struct file_operations tracing_ctrl_fops = {
+static const struct file_operations tracing_ctrl_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_ctrl_read,
 	.write		= tracing_ctrl_write,
 };
 
-static struct file_operations set_tracer_fops = {
+static const struct file_operations set_tracer_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_set_trace_read,
 	.write		= tracing_set_trace_write,
 };
 
-static struct file_operations tracing_pipe_fops = {
+static const struct file_operations tracing_pipe_fops = {
 	.open		= tracing_open_pipe,
 	.poll		= tracing_poll_pipe,
 	.read		= tracing_read_pipe,
@@ -2953,13 +2953,13 @@ static struct file_operations tracing_pipe_fops = {
 	.release	= tracing_release_pipe,
 };
 
-static struct file_operations tracing_entries_fops = {
+static const struct file_operations tracing_entries_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_entries_read,
 	.write		= tracing_entries_write,
 };
 
-static struct file_operations tracing_mark_fops = {
+static const struct file_operations tracing_mark_fops = {
 	.open		= tracing_open_generic,
 	.write		= tracing_mark_write,
 };
@@ -3240,7 +3240,7 @@ tracing_read_dyn_info(struct file *filp, char __user *ubuf,
 	return r;
 }
 
-static struct file_operations tracing_dyn_info_fops = {
+static const struct file_operations tracing_dyn_info_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_read_dyn_info,
 };

kernel/trace/trace_event_types.h

@@ -0,0 +1,165 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM	ftrace
+
+/*
+ * We cheat and use the proto type field as the ID
+ * and args as the entry type (minus 'struct')
+ */
+TRACE_EVENT_FORMAT(function, TRACE_FN, ftrace_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned long, ip, ip)
+		TRACE_FIELD(unsigned long, parent_ip, parent_ip)
+	),
+	TPRAWFMT(" %lx <-- %lx")
+);
+
+TRACE_EVENT_FORMAT(funcgraph_entry, TRACE_GRAPH_ENT,
+		   ftrace_graph_ent_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned long, graph_ent.func, func)
+		TRACE_FIELD(int, graph_ent.depth, depth)
+	),
+	TPRAWFMT("--> %lx (%d)")
+);
+
+TRACE_EVENT_FORMAT(funcgraph_exit, TRACE_GRAPH_RET,
+		   ftrace_graph_ret_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned long, ret.func, func)
+		TRACE_FIELD(int, ret.depth, depth)
+	),
+	TPRAWFMT("<-- %lx (%d)")
+);
+
+TRACE_EVENT_FORMAT(wakeup, TRACE_WAKE, ctx_switch_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned int, prev_pid, prev_pid)
+		TRACE_FIELD(unsigned char, prev_prio, prev_prio)
+		TRACE_FIELD(unsigned char, prev_state, prev_state)
+		TRACE_FIELD(unsigned int, next_pid, next_pid)
+		TRACE_FIELD(unsigned char, next_prio, next_prio)
+		TRACE_FIELD(unsigned char, next_state, next_state)
+		TRACE_FIELD(unsigned int, next_cpu, next_cpu)
+	),
+	TPRAWFMT("%u:%u:%u  ==+ %u:%u:%u [%03u]")
+);
+
+TRACE_EVENT_FORMAT(context_switch, TRACE_CTX, ctx_switch_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned int, prev_pid, prev_pid)
+		TRACE_FIELD(unsigned char, prev_prio, prev_prio)
+		TRACE_FIELD(unsigned char, prev_state, prev_state)
+		TRACE_FIELD(unsigned int, next_pid, next_pid)
+		TRACE_FIELD(unsigned char, next_prio, next_prio)
+		TRACE_FIELD(unsigned char, next_state, next_state)
+		TRACE_FIELD(unsigned int, next_cpu, next_cpu)
+	),
+	TPRAWFMT("%u:%u:%u  ==+ %u:%u:%u [%03u]")
+);
+
+TRACE_EVENT_FORMAT(special, TRACE_SPECIAL, special_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned long, arg1, arg1)
+		TRACE_FIELD(unsigned long, arg2, arg2)
+		TRACE_FIELD(unsigned long, arg3, arg3)
+	),
+	TPRAWFMT("(%08lx) (%08lx) (%08lx)")
+);
+
+/*
+ * Stack-trace entry:
+ */
+
+/* #define FTRACE_STACK_ENTRIES   8 */
+
+TRACE_EVENT_FORMAT(kernel_stack, TRACE_STACK, stack_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned long, caller[0], stack0)
+		TRACE_FIELD(unsigned long, caller[1], stack1)
+		TRACE_FIELD(unsigned long, caller[2], stack2)
+		TRACE_FIELD(unsigned long, caller[3], stack3)
+		TRACE_FIELD(unsigned long, caller[4], stack4)
+		TRACE_FIELD(unsigned long, caller[5], stack5)
+		TRACE_FIELD(unsigned long, caller[6], stack6)
+		TRACE_FIELD(unsigned long, caller[7], stack7)
+	),
+	TPRAWFMT("\t=> (%08lx)\n\t=> (%08lx)\n\t=> (%08lx)\n\t=> (%08lx)\n"
+		 "\t=> (%08lx)\n\t=> (%08lx)\n\t=> (%08lx)\n\t=> (%08lx)\n")
+);
+
+TRACE_EVENT_FORMAT(user_stack, TRACE_USER_STACK, userstack_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned long, caller[0], stack0)
+		TRACE_FIELD(unsigned long, caller[1], stack1)
+		TRACE_FIELD(unsigned long, caller[2], stack2)
+		TRACE_FIELD(unsigned long, caller[3], stack3)
+		TRACE_FIELD(unsigned long, caller[4], stack4)
+		TRACE_FIELD(unsigned long, caller[5], stack5)
+		TRACE_FIELD(unsigned long, caller[6], stack6)
+		TRACE_FIELD(unsigned long, caller[7], stack7)
+	),
+	TPRAWFMT("\t=> (%08lx)\n\t=> (%08lx)\n\t=> (%08lx)\n\t=> (%08lx)\n"
+		 "\t=> (%08lx)\n\t=> (%08lx)\n\t=> (%08lx)\n\t=> (%08lx)\n")
+);
+
+TRACE_EVENT_FORMAT(print, TRACE_PRINT, print_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned long, ip, ip)
+		TRACE_FIELD(unsigned int, depth, depth)
+		TRACE_FIELD_ZERO_CHAR(buf)
+	),
+	TPRAWFMT("%08lx (%d) %s")
+);
+
+TRACE_EVENT_FORMAT(branch, TRACE_BRANCH, trace_branch, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(unsigned int, line, line)
+		TRACE_FIELD_SPECIAL(char func[TRACE_FUNC_SIZE+1], func, func)
+		TRACE_FIELD_SPECIAL(char file[TRACE_FUNC_SIZE+1], file, file)
+		TRACE_FIELD(char, correct, correct)
+	),
+	TPRAWFMT("%u:%s:%s (%u)")
+);
+
+TRACE_EVENT_FORMAT(hw_branch, TRACE_HW_BRANCHES, hw_branch_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(u64, from, from)
+		TRACE_FIELD(u64, to, to)
+	),
+	TPRAWFMT("from: %llx to: %llx")
+);
+
+TRACE_EVENT_FORMAT(power, TRACE_POWER, trace_power, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(ktime_t, state_data.stamp, stamp)
+		TRACE_FIELD(ktime_t, state_data.end, end)
+		TRACE_FIELD(int, state_data.type, type)
+		TRACE_FIELD(int, state_data.state, state)
+	),
+	TPRAWFMT("%llx->%llx type:%u state:%u")
+);
+
+TRACE_EVENT_FORMAT(kmem_alloc, TRACE_KMEM_ALLOC, kmemtrace_alloc_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(enum kmemtrace_type_id, type_id, type_id)
+		TRACE_FIELD(unsigned long, call_site, call_site)
+		TRACE_FIELD(const void *, ptr, ptr)
+		TRACE_FIELD(size_t, bytes_req, bytes_req)
+		TRACE_FIELD(size_t, bytes_alloc, bytes_alloc)
+		TRACE_FIELD(gfp_t, gfp_flags, gfp_flags)
+		TRACE_FIELD(int, node, node)
+	),
+	TPRAWFMT("type:%u call_site:%lx ptr:%p req:%lu alloc:%lu"
+		 " flags:%x node:%d")
+);
+
+TRACE_EVENT_FORMAT(kmem_free, TRACE_KMEM_FREE, kmemtrace_free_entry, ignore,
+	TRACE_STRUCT(
+		TRACE_FIELD(enum kmemtrace_type_id, type_id, type_id)
+		TRACE_FIELD(unsigned long, call_site, call_site)
+		TRACE_FIELD(const void *, ptr, ptr)
+	),
+	TPRAWFMT("type:%u call_site:%lx ptr:%p")
+);
+
+#undef TRACE_SYSTEM

kernel/trace/trace_events.c

@@ -656,11 +656,13 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
 		return -1;
 	}
 
-	entry = debugfs_create_file("enable", 0644, call->dir, call,
-				    &ftrace_enable_fops);
-	if (!entry)
-		pr_warning("Could not create debugfs "
-			   "'%s/enable' entry\n", call->name);
+	if (call->regfunc) {
+		entry = debugfs_create_file("enable", 0644, call->dir, call,
+					    &ftrace_enable_fops);
+		if (!entry)
+			pr_warning("Could not create debugfs "
+				   "'%s/enable' entry\n", call->name);
+	}
 
 	/* Only let type be writable, if we can change it */
 	entry = debugfs_create_file("type",

kernel/trace/trace_events_stage_2.h

@@ -75,56 +75,5 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags)	\
 
 #include <trace/trace_event_types.h>
 
-/*
- * Setup the showing format of trace point.
- *
- * int
- * ftrace_format_##call(struct trace_seq *s)
- * {
- * 	struct ftrace_raw_##call field;
- * 	int ret;
- *
- * 	ret = trace_seq_printf(s, #type " " #item ";"
- * 			       " size:%d; offset:%d;\n",
- * 			       sizeof(field.type),
- * 			       offsetof(struct ftrace_raw_##call,
- * 					item));
- *
- * }
- */
-
-#undef TRACE_FIELD
-#define TRACE_FIELD(type, item, assign)					\
-	ret = trace_seq_printf(s, "\tfield:" #type " " #item ";\t"	\
-			       "offset:%lu;\tsize:%lu;\n",		\
-			       offsetof(typeof(field), item),		\
-			       sizeof(field.item));			\
-	if (!ret)							\
-		return 0;
-
-
-#undef TRACE_FIELD_SPECIAL
-#define TRACE_FIELD_SPECIAL(type_item, item, cmd)			\
-	ret = trace_seq_printf(s, "\tfield special:" #type_item ";\t"	\
-			       "offset:%lu;\tsize:%lu;\n",		\
-			       offsetof(typeof(field), item),		\
-			       sizeof(field.item));			\
-	if (!ret)							\
-		return 0;
-
-#undef TRACE_EVENT_FORMAT
-#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)	\
-int									\
-ftrace_format_##call(struct trace_seq *s)				\
-{									\
-	struct ftrace_raw_##call field;					\
-	int ret;							\
-									\
-	tstruct;							\
-									\
-	trace_seq_printf(s, "\nprint fmt: \"%s\"\n", tpfmt);		\
-									\
-	return ret;							\
-}
-
+#include "trace_format.h"
 #include <trace/trace_event_types.h>

kernel/trace/trace_export.c

@@ -0,0 +1,81 @@
+/*
+ * trace_export.c - export basic ftrace utilities to user space
+ *
+ * Copyright (C) 2009 Steven Rostedt <srostedt@redhat.com>
+ */
+#include <linux/stringify.h>
+#include <linux/kallsyms.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+
+#include "trace_output.h"
+
+#include "trace_format.h"
+
+#undef TRACE_FIELD_ZERO_CHAR
+#define TRACE_FIELD_ZERO_CHAR(item)				\
+	ret = trace_seq_printf(s, "\tfield: char " #item ";\t"	\
+			       "offset:%lu;\tsize:0;\n",	\
+			       offsetof(typeof(field), item));	\
+	if (!ret)						\
+		return 0;
+
+
+#undef TPRAWFMT
+#define TPRAWFMT(args...) args
+
+#undef TRACE_EVENT_FORMAT
+#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)	\
+static int								\
+ftrace_format_##call(struct trace_seq *s)				\
+{									\
+	struct args field;						\
+	int ret;							\
+									\
+	tstruct;							\
+									\
+	trace_seq_printf(s, "\nprint fmt: \"%s\"\n", tpfmt);		\
+									\
+	return ret;							\
+}
+
+#include "trace_event_types.h"
+
+#undef TRACE_ZERO_CHAR
+#define TRACE_ZERO_CHAR(arg)
+
+#undef TRACE_FIELD
+#define TRACE_FIELD(type, item, assign)\
+	entry->item = assign;
+
+#undef TRACE_FIELD
+#define TRACE_FIELD(type, item, assign)\
+	entry->item = assign;
+
+#undef TPCMD
+#define TPCMD(cmd...)	cmd
+
+#undef TRACE_ENTRY
+#define TRACE_ENTRY	entry
+
+#undef TRACE_FIELD_SPECIAL
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
+	cmd;
+
+#undef TRACE_EVENT_FORMAT
+#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)	\
+									\
+static struct ftrace_event_call __used					\
+__attribute__((__aligned__(4)))						\
+__attribute__((section("_ftrace_events"))) event_##call = {		\
+	.name 			= #call,				\
+	.id			= proto,				\
+	.system			= __stringify(TRACE_SYSTEM),		\
+	.show_format		= ftrace_format_##call,			\
+}
+#include "trace_event_types.h"

kernel/trace/trace_format.h

@@ -0,0 +1,55 @@
+/*
+ * Setup the showing format of trace point.
+ *
+ * int
+ * ftrace_format_##call(struct trace_seq *s)
+ * {
+ *	struct ftrace_raw_##call field;
+ *	int ret;
+ *
+ *	ret = trace_seq_printf(s, #type " " #item ";"
+ *			       " size:%d; offset:%d;\n",
+ *			       sizeof(field.type),
+ *			       offsetof(struct ftrace_raw_##call,
+ *					item));
+ *
+ * }
+ */
+
+#undef TRACE_STRUCT
+#define TRACE_STRUCT(args...) args
+
+#undef TRACE_FIELD
+#define TRACE_FIELD(type, item, assign)					\
+	ret = trace_seq_printf(s, "\tfield:" #type " " #item ";\t"	\
+			       "offset:%lu;\tsize:%lu;\n",		\
+			       offsetof(typeof(field), item),		\
+			       sizeof(field.item));			\
+	if (!ret)							\
+		return 0;
+
+
+#undef TRACE_FIELD_SPECIAL
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd)			\
+	ret = trace_seq_printf(s, "\tfield special:" #type_item ";\t"	\
+			       "offset:%lu;\tsize:%lu;\n",		\
+			       offsetof(typeof(field), item),		\
+			       sizeof(field.item));			\
+	if (!ret)							\
+		return 0;
+
+#undef TRACE_EVENT_FORMAT
+#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)	\
+static int								\
+ftrace_format_##call(struct trace_seq *s)				\
+{									\
+	struct ftrace_raw_##call field;					\
+	int ret;							\
+									\
+	tstruct;							\
+									\
+	trace_seq_printf(s, "\nprint fmt: \"%s\"\n", tpfmt);		\
+									\
+	return ret;							\
+}
+

kernel/trace/trace_sysprof.c

@@ -314,7 +314,7 @@ sysprof_sample_write(struct file *filp, const char __user *ubuf,
 	return cnt;
 }
 
-static struct file_operations sysprof_sample_fops = {
+static const struct file_operations sysprof_sample_fops = {
 	.read		= sysprof_sample_read,
 	.write		= sysprof_sample_write,
 };