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authorLinus Torvalds <torvalds@linux-foundation.org>2025-12-05 09:51:37 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2025-12-05 09:51:37 -0800
commit69c5079b49fa120c1a108b6e28b3a6a8e4ae2db5 (patch)
treed3b2ecb61bcbf9d9d9a8f9fa7f620af0030b514d /kernel/trace/trace.h
parent36492b7141b9abc967e92c991af32c670351dc16 (diff)
parentf6ed9c5d3190cf18382ee75e0420602101f53586 (diff)
Merge tag 'trace-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt: - Extend tracing option mask to 64 bits The trace options were defined by a 32 bit variable. This limits the tracing instances to have a total of 32 different options. As that limit has been hit, and more options are being added, increase the option mask to a 64 bit number, doubling the number of options available. As this is required for the kprobe topic branches as well as the tracing topic branch, a separate branch was created and merged into both. - Make trace_user_fault_read() available for the rest of tracing The function trace_user_fault_read() is used by trace_marker file read to allow reading user space to be done fast and without locking or allocations. Make this available so that the system call trace events can use it too. - Have system call trace events read user space values Now that the system call trace events callbacks are called in a faultable context, take advantage of this and read the user space buffers for various system calls. For example, show the path name of the openat system call instead of just showing the pointer to that path name in user space. Also show the contents of the buffer of the write system call. Several system call trace events are updated to make tracing into a light weight strace tool for all applications in the system. - Update perf system call tracing to do the same - And a config and syscall_user_buf_size file to control the size of the buffer Limit the amount of data that can be read from user space. The default size is 63 bytes but that can be expanded to 165 bytes. - Allow the persistent ring buffer to print system calls normally The persistent ring buffer prints trace events by their type and ignores the print_fmt. This is because the print_fmt may change from kernel to kernel. As the system call output is fixed by the system call ABI itself, there's no reason to limit that. This makes reading the system call events in the persistent ring buffer much nicer and easier to understand. - Add options to show text offset to function profiler The function profiler that counts the number of times a function is hit currently lists all functions by its name and offset. But this becomes ambiguous when there are several functions with the same name. Add a tracing option that changes the output to be that of '_text+offset' instead. Now a user space tool can use this information to map the '_text+offset' to the unique function it is counting. - Report bad dynamic event command If a bad command is passed to the dynamic_events file, report it properly in the error log. - Clean up tracer options Clean up the tracer option code a bit, by removing some useless code and also using switch statements instead of a series of if statements. - Have tracing options be instance specific Tracers can have their own options (function tracer, irqsoff tracer, function graph tracer, etc). But now that the same tracer can be enabled in multiple trace instances, their options are still global. The API is per instance, thus changing one affects other instances. This isn't even consistent, as the option take affect differently depending on when an tracer started in an instance. Make the options for instances only affect the instance it is changed under. - Optimize pid_list lock contention Whenever the pid_list is read, it uses a spin lock. This happens at every sched switch. Taking the lock at sched switch can be removed by instead using a seqlock counter. - Clean up the trace trigger structures The trigger code uses two different structures to implement a single tigger. This was due to trying to reuse code for the two different types of triggers (always on trigger, and count limited trigger). But by adding a single field to one structure, the other structure could be absorbed into the first structure making he code easier to understand. - Create a bulk garbage collector for trace triggers If user space has triggers for several hundreds of events and then removes them, it can take several seconds to complete. This is because each removal calls tracepoint_synchronize_unregister() that can take hundreds of milliseconds to complete. Instead, create a helper thread that will do the clean up. When a trigger is removed, it will create the kthread if it isn't already created, and then add the trigger to a llist. The kthread will take the items off the llist, call tracepoint_synchronize_unregister(), and then remove the items it took off. It will then check if there's more items to free before sleeping. This makes user space removing all these triggers to finish in less than a second. - Allow function tracing of some of the tracing infrastructure code Because the tracing code can cause recursion issues if it is traced by the function tracer the entire tracing directory disables function tracing. But not all of tracing causes issues if it is traced. Namely, the event tracing code. Add a config that enables some of the tracing code to be traced to help in debugging it. Note, when this is enabled, it does add noise to general function tracing, especially if events are enabled as well (which is a common case). - Add boot-time backup instance for persistent buffer The persistent ring buffer is used mostly for kernel crash analysis in the field. One issue is that if there's a crash, the data in the persistent ring buffer must be read before tracing can begin using it. This slows down the boot process. Once tracing starts in the persistent ring buffer, the old data must be freed and the addresses no longer match and old events can't be in the buffer with new events. Create a way to create a backup buffer that copies the persistent ring buffer at boot up. Then after a crash, the always on tracer can begin immediately as well as the normal boot process while the crash analysis tooling uses the backup buffer. After the backup buffer is finished being read, it can be removed. - Enable function graph args and return address options at the same time Currently the when reading of arguments in the function graph tracer is enabled, the option to record the parent function in the entry event can not be enabled. Update the code so that it can. - Add new struct_offset() helper macro Add a new macro that takes a pointer to a structure and a name of one of its members and it will return the offset of that member. This allows the ring buffer code to simplify the following: From: size = struct_size(entry, buf, cnt - sizeof(entry->id)); To: size = struct_offset(entry, id) + cnt; There should be other simplifications that this macro can help out with as well * tag 'trace-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (42 commits) overflow: Introduce struct_offset() to get offset of member function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously tracing: Add boot-time backup of persistent ring buffer ftrace: Allow tracing of some of the tracing code tracing: Use strim() in trigger_process_regex() instead of skip_spaces() tracing: Add bulk garbage collection of freeing event_trigger_data tracing: Remove unneeded event_mutex lock in event_trigger_regex_release() tracing: Merge struct event_trigger_ops into struct event_command tracing: Remove get_trigger_ops() and add count_func() from trigger ops tracing: Show the tracer options in boot-time created instance ftrace: Avoid redundant initialization in register_ftrace_direct tracing: Remove unused variable in tracing_trace_options_show() fgraph: Make fgraph_no_sleep_time signed tracing: Convert function graph set_flags() to use a switch() statement tracing: Have function graph tracer option sleep-time be per instance tracing: Move graph-time out of function graph options tracing: Have function graph tracer option funcgraph-irqs be per instance trace/pid_list: optimize pid_list->lock contention tracing: Have function graph tracer define options per instance tracing: Have function tracer define options per instance ...
Diffstat (limited to 'kernel/trace/trace.h')
-rw-r--r--kernel/trace/trace.h230
1 files changed, 140 insertions, 90 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 85eabb454bee..c2b61bcd912f 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -22,6 +22,7 @@
#include <linux/ctype.h>
#include <linux/once_lite.h>
#include <linux/ftrace_regs.h>
+#include <linux/llist.h>
#include "pid_list.h"
@@ -131,6 +132,8 @@ enum trace_type {
#define HIST_STACKTRACE_SIZE (HIST_STACKTRACE_DEPTH * sizeof(unsigned long))
#define HIST_STACKTRACE_SKIP 5
+#define SYSCALL_FAULT_USER_MAX 165
+
/*
* syscalls are special, and need special handling, this is why
* they are not included in trace_entries.h
@@ -216,7 +219,7 @@ struct array_buffer {
int cpu;
};
-#define TRACE_FLAGS_MAX_SIZE 32
+#define TRACE_FLAGS_MAX_SIZE 64
struct trace_options {
struct tracer *tracer;
@@ -390,7 +393,8 @@ struct trace_array {
int buffer_percent;
unsigned int n_err_log_entries;
struct tracer *current_trace;
- unsigned int trace_flags;
+ struct tracer_flags *current_trace_flags;
+ u64 trace_flags;
unsigned char trace_flags_index[TRACE_FLAGS_MAX_SIZE];
unsigned int flags;
raw_spinlock_t start_lock;
@@ -404,6 +408,7 @@ struct trace_array {
struct list_head systems;
struct list_head events;
struct list_head marker_list;
+ struct list_head tracers;
struct trace_event_file *trace_marker_file;
cpumask_var_t tracing_cpumask; /* only trace on set CPUs */
/* one per_cpu trace_pipe can be opened by only one user */
@@ -430,6 +435,7 @@ struct trace_array {
int function_enabled;
#endif
int no_filter_buffering_ref;
+ unsigned int syscall_buf_sz;
struct list_head hist_vars;
#ifdef CONFIG_TRACER_SNAPSHOT
struct cond_snapshot *cond_snapshot;
@@ -448,6 +454,7 @@ enum {
TRACE_ARRAY_FL_LAST_BOOT = BIT(2),
TRACE_ARRAY_FL_MOD_INIT = BIT(3),
TRACE_ARRAY_FL_MEMMAP = BIT(4),
+ TRACE_ARRAY_FL_VMALLOC = BIT(5),
};
#ifdef CONFIG_MODULES
@@ -631,9 +638,10 @@ struct tracer {
u32 old_flags, u32 bit, int set);
/* Return 0 if OK with change, else return non-zero */
int (*flag_changed)(struct trace_array *tr,
- u32 mask, int set);
+ u64 mask, int set);
struct tracer *next;
struct tracer_flags *flags;
+ struct tracer_flags *default_flags;
int enabled;
bool print_max;
bool allow_instances;
@@ -937,8 +945,6 @@ static __always_inline bool ftrace_hash_empty(struct ftrace_hash *hash)
#define TRACE_GRAPH_PRINT_FILL_SHIFT 28
#define TRACE_GRAPH_PRINT_FILL_MASK (0x3 << TRACE_GRAPH_PRINT_FILL_SHIFT)
-extern void ftrace_graph_sleep_time_control(bool enable);
-
#ifdef CONFIG_FUNCTION_PROFILER
extern void ftrace_graph_graph_time_control(bool enable);
#else
@@ -958,7 +964,8 @@ extern int __trace_graph_entry(struct trace_array *tr,
extern int __trace_graph_retaddr_entry(struct trace_array *tr,
struct ftrace_graph_ent *trace,
unsigned int trace_ctx,
- unsigned long retaddr);
+ unsigned long retaddr,
+ struct ftrace_regs *fregs);
extern void __trace_graph_return(struct trace_array *tr,
struct ftrace_graph_ret *trace,
unsigned int trace_ctx,
@@ -1109,7 +1116,8 @@ static inline void ftrace_graph_addr_finish(struct fgraph_ops *gops, struct ftra
#endif /* CONFIG_DYNAMIC_FTRACE */
extern unsigned int fgraph_max_depth;
-extern bool fgraph_sleep_time;
+extern int fgraph_no_sleep_time;
+extern bool fprofile_no_sleep_time;
static inline bool
ftrace_graph_ignore_func(struct fgraph_ops *gops, struct ftrace_graph_ent *trace)
@@ -1345,11 +1353,11 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
# define FUNCTION_FLAGS \
C(FUNCTION, "function-trace"), \
C(FUNC_FORK, "function-fork"),
-# define FUNCTION_DEFAULT_FLAGS TRACE_ITER_FUNCTION
+# define FUNCTION_DEFAULT_FLAGS TRACE_ITER(FUNCTION)
#else
# define FUNCTION_FLAGS
# define FUNCTION_DEFAULT_FLAGS 0UL
-# define TRACE_ITER_FUNC_FORK 0UL
+# define TRACE_ITER_FUNC_FORK_BIT -1
#endif
#ifdef CONFIG_STACKTRACE
@@ -1359,6 +1367,24 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
# define STACK_FLAGS
#endif
+#ifdef CONFIG_FUNCTION_PROFILER
+# define PROFILER_FLAGS \
+ C(PROF_TEXT_OFFSET, "prof-text-offset"),
+# ifdef CONFIG_FUNCTION_GRAPH_TRACER
+# define FPROFILE_FLAGS \
+ C(GRAPH_TIME, "graph-time"),
+# define FPROFILE_DEFAULT_FLAGS TRACE_ITER(GRAPH_TIME)
+# else
+# define FPROFILE_FLAGS
+# define FPROFILE_DEFAULT_FLAGS 0UL
+# endif
+#else
+# define PROFILER_FLAGS
+# define FPROFILE_FLAGS
+# define FPROFILE_DEFAULT_FLAGS 0UL
+# define TRACE_ITER_PROF_TEXT_OFFSET_BIT -1
+#endif
+
/*
* trace_iterator_flags is an enumeration that defines bit
* positions into trace_flags that controls the output.
@@ -1391,13 +1417,15 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
C(MARKERS, "markers"), \
C(EVENT_FORK, "event-fork"), \
C(TRACE_PRINTK, "trace_printk_dest"), \
- C(COPY_MARKER, "copy_trace_marker"),\
+ C(COPY_MARKER, "copy_trace_marker"), \
C(PAUSE_ON_TRACE, "pause-on-trace"), \
C(HASH_PTR, "hash-ptr"), /* Print hashed pointer */ \
FUNCTION_FLAGS \
FGRAPH_FLAGS \
STACK_FLAGS \
- BRANCH_FLAGS
+ BRANCH_FLAGS \
+ PROFILER_FLAGS \
+ FPROFILE_FLAGS
/*
* By defining C, we can make TRACE_FLAGS a list of bit names
@@ -1413,20 +1441,17 @@ enum trace_iterator_bits {
};
/*
- * By redefining C, we can make TRACE_FLAGS a list of masks that
- * use the bits as defined above.
+ * And use TRACE_ITER(flag) to define the bit masks.
*/
-#undef C
-#define C(a, b) TRACE_ITER_##a = (1 << TRACE_ITER_##a##_BIT)
-
-enum trace_iterator_flags { TRACE_FLAGS };
+#define TRACE_ITER(flag) \
+ (TRACE_ITER_##flag##_BIT < 0 ? 0 : 1ULL << (TRACE_ITER_##flag##_BIT))
/*
* TRACE_ITER_SYM_MASK masks the options in trace_flags that
* control the output of kernel symbols.
*/
#define TRACE_ITER_SYM_MASK \
- (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
+ (TRACE_ITER(PRINT_PARENT)|TRACE_ITER(SYM_OFFSET)|TRACE_ITER(SYM_ADDR))
extern struct tracer nop_trace;
@@ -1435,7 +1460,7 @@ extern int enable_branch_tracing(struct trace_array *tr);
extern void disable_branch_tracing(void);
static inline int trace_branch_enable(struct trace_array *tr)
{
- if (tr->trace_flags & TRACE_ITER_BRANCH)
+ if (tr->trace_flags & TRACE_ITER(BRANCH))
return enable_branch_tracing(tr);
return 0;
}
@@ -1531,6 +1556,23 @@ void trace_buffered_event_enable(void);
void early_enable_events(struct trace_array *tr, char *buf, bool disable_first);
+struct trace_user_buf;
+struct trace_user_buf_info {
+ struct trace_user_buf __percpu *tbuf;
+ size_t size;
+ int ref;
+};
+
+typedef int (*trace_user_buf_copy)(char *dst, const char __user *src,
+ size_t size, void *data);
+int trace_user_fault_init(struct trace_user_buf_info *tinfo, size_t size);
+int trace_user_fault_get(struct trace_user_buf_info *tinfo);
+int trace_user_fault_put(struct trace_user_buf_info *tinfo);
+void trace_user_fault_destroy(struct trace_user_buf_info *tinfo);
+char *trace_user_fault_read(struct trace_user_buf_info *tinfo,
+ const char __user *ptr, size_t size,
+ trace_user_buf_copy copy_func, void *data);
+
static inline void
__trace_event_discard_commit(struct trace_buffer *buffer,
struct ring_buffer_event *event)
@@ -1752,13 +1794,13 @@ extern void clear_event_triggers(struct trace_array *tr);
enum {
EVENT_TRIGGER_FL_PROBE = BIT(0),
+ EVENT_TRIGGER_FL_COUNT = BIT(1),
};
struct event_trigger_data {
unsigned long count;
int ref;
int flags;
- const struct event_trigger_ops *ops;
struct event_command *cmd_ops;
struct event_filter __rcu *filter;
char *filter_str;
@@ -1769,6 +1811,7 @@ struct event_trigger_data {
char *name;
struct list_head named_list;
struct event_trigger_data *named_data;
+ struct llist_node llist;
};
/* Avoid typos */
@@ -1783,6 +1826,10 @@ struct enable_trigger_data {
bool hist;
};
+bool event_trigger_count(struct event_trigger_data *data,
+ struct trace_buffer *buffer, void *rec,
+ struct ring_buffer_event *event);
+
extern int event_enable_trigger_print(struct seq_file *m,
struct event_trigger_data *data);
extern void event_enable_trigger_free(struct event_trigger_data *data);
@@ -1846,64 +1893,6 @@ extern void event_file_get(struct trace_event_file *file);
extern void event_file_put(struct trace_event_file *file);
/**
- * struct event_trigger_ops - callbacks for trace event triggers
- *
- * The methods in this structure provide per-event trigger hooks for
- * various trigger operations.
- *
- * The @init and @free methods are used during trigger setup and
- * teardown, typically called from an event_command's @parse()
- * function implementation.
- *
- * The @print method is used to print the trigger spec.
- *
- * The @trigger method is the function that actually implements the
- * trigger and is called in the context of the triggering event
- * whenever that event occurs.
- *
- * All the methods below, except for @init() and @free(), must be
- * implemented.
- *
- * @trigger: The trigger 'probe' function called when the triggering
- * event occurs. The data passed into this callback is the data
- * that was supplied to the event_command @reg() function that
- * registered the trigger (see struct event_command) along with
- * the trace record, rec.
- *
- * @init: An optional initialization function called for the trigger
- * when the trigger is registered (via the event_command reg()
- * function). This can be used to perform per-trigger
- * initialization such as incrementing a per-trigger reference
- * count, for instance. This is usually implemented by the
- * generic utility function @event_trigger_init() (see
- * trace_event_triggers.c).
- *
- * @free: An optional de-initialization function called for the
- * trigger when the trigger is unregistered (via the
- * event_command @reg() function). This can be used to perform
- * per-trigger de-initialization such as decrementing a
- * per-trigger reference count and freeing corresponding trigger
- * data, for instance. This is usually implemented by the
- * generic utility function @event_trigger_free() (see
- * trace_event_triggers.c).
- *
- * @print: The callback function invoked to have the trigger print
- * itself. This is usually implemented by a wrapper function
- * that calls the generic utility function @event_trigger_print()
- * (see trace_event_triggers.c).
- */
-struct event_trigger_ops {
- void (*trigger)(struct event_trigger_data *data,
- struct trace_buffer *buffer,
- void *rec,
- struct ring_buffer_event *rbe);
- int (*init)(struct event_trigger_data *data);
- void (*free)(struct event_trigger_data *data);
- int (*print)(struct seq_file *m,
- struct event_trigger_data *data);
-};
-
-/**
* struct event_command - callbacks and data members for event commands
*
* Event commands are invoked by users by writing the command name
@@ -1952,7 +1941,7 @@ struct event_trigger_ops {
*
* @reg: Adds the trigger to the list of triggers associated with the
* event, and enables the event trigger itself, after
- * initializing it (via the event_trigger_ops @init() function).
+ * initializing it (via the event_command @init() function).
* This is also where commands can use the @trigger_type value to
* make the decision as to whether or not multiple instances of
* the trigger should be allowed. This is usually implemented by
@@ -1961,7 +1950,7 @@ struct event_trigger_ops {
*
* @unreg: Removes the trigger from the list of triggers associated
* with the event, and disables the event trigger itself, after
- * initializing it (via the event_trigger_ops @free() function).
+ * initializing it (via the event_command @free() function).
* This is usually implemented by the generic utility function
* @unregister_trigger() (see trace_event_triggers.c).
*
@@ -1975,12 +1964,41 @@ struct event_trigger_ops {
* ignored. This is usually implemented by the generic utility
* function @set_trigger_filter() (see trace_event_triggers.c).
*
- * @get_trigger_ops: The callback function invoked to retrieve the
- * event_trigger_ops implementation associated with the command.
- * This callback function allows a single event_command to
- * support multiple trigger implementations via different sets of
- * event_trigger_ops, depending on the value of the @param
- * string.
+ * All the methods below, except for @init() and @free(), must be
+ * implemented.
+ *
+ * @trigger: The trigger 'probe' function called when the triggering
+ * event occurs. The data passed into this callback is the data
+ * that was supplied to the event_command @reg() function that
+ * registered the trigger (see struct event_command) along with
+ * the trace record, rec.
+ *
+ * @count_func: If defined and a numeric parameter is passed to the
+ * trigger, then this function will be called before @trigger
+ * is called. If this function returns false, then @trigger is not
+ * executed.
+ *
+ * @init: An optional initialization function called for the trigger
+ * when the trigger is registered (via the event_command reg()
+ * function). This can be used to perform per-trigger
+ * initialization such as incrementing a per-trigger reference
+ * count, for instance. This is usually implemented by the
+ * generic utility function @event_trigger_init() (see
+ * trace_event_triggers.c).
+ *
+ * @free: An optional de-initialization function called for the
+ * trigger when the trigger is unregistered (via the
+ * event_command @reg() function). This can be used to perform
+ * per-trigger de-initialization such as decrementing a
+ * per-trigger reference count and freeing corresponding trigger
+ * data, for instance. This is usually implemented by the
+ * generic utility function @event_trigger_free() (see
+ * trace_event_triggers.c).
+ *
+ * @print: The callback function invoked to have the trigger print
+ * itself. This is usually implemented by a wrapper function
+ * that calls the generic utility function @event_trigger_print()
+ * (see trace_event_triggers.c).
*/
struct event_command {
struct list_head list;
@@ -2001,7 +2019,18 @@ struct event_command {
int (*set_filter)(char *filter_str,
struct event_trigger_data *data,
struct trace_event_file *file);
- const struct event_trigger_ops *(*get_trigger_ops)(char *cmd, char *param);
+ void (*trigger)(struct event_trigger_data *data,
+ struct trace_buffer *buffer,
+ void *rec,
+ struct ring_buffer_event *rbe);
+ bool (*count_func)(struct event_trigger_data *data,
+ struct trace_buffer *buffer,
+ void *rec,
+ struct ring_buffer_event *rbe);
+ int (*init)(struct event_trigger_data *data);
+ void (*free)(struct event_trigger_data *data);
+ int (*print)(struct seq_file *m,
+ struct event_trigger_data *data);
};
/**
@@ -2022,7 +2051,7 @@ struct event_command {
* either committed or discarded. At that point, if any commands
* have deferred their triggers, those commands are finally
* invoked following the close of the current event. In other
- * words, if the event_trigger_ops @func() probe implementation
+ * words, if the event_command @func() probe implementation
* itself logs to the trace buffer, this flag should be set,
* otherwise it can be left unspecified.
*
@@ -2064,8 +2093,8 @@ extern const char *__stop___tracepoint_str[];
void trace_printk_control(bool enabled);
void trace_printk_start_comm(void);
-int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set);
-int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled);
+int trace_keep_overwrite(struct tracer *tracer, u64 mask, int set);
+int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled);
/* Used from boot time tracer */
extern int trace_set_options(struct trace_array *tr, char *option);
@@ -2248,4 +2277,25 @@ static inline int rv_init_interface(void)
*/
#define FTRACE_TRAMPOLINE_MARKER ((unsigned long) INT_MAX)
+/*
+ * This is used to get the address of the args array based on
+ * the type of the entry.
+ */
+#define FGRAPH_ENTRY_ARGS(e) \
+ ({ \
+ unsigned long *_args; \
+ struct ftrace_graph_ent_entry *_e = e; \
+ \
+ if (IS_ENABLED(CONFIG_FUNCTION_GRAPH_RETADDR) && \
+ e->ent.type == TRACE_GRAPH_RETADDR_ENT) { \
+ struct fgraph_retaddr_ent_entry *_re; \
+ \
+ _re = (typeof(_re))_e; \
+ _args = _re->args; \
+ } else { \
+ _args = _e->args; \
+ } \
+ _args; \
+ })
+
#endif /* _LINUX_KERNEL_TRACE_H */