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Commit 50307a45 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Steven Rostedt
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tracing/syscalls: Init print_fmt for syscall events 



This is part of a patch set that removes the show_format method
in the ftrace event macros.

Add the print_fmt initialization to the syscall events.
The print_fmt is still not used, but will be in the follow up
patches.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4B273D41.609@cn.fujitsu.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 509e760c

kernel/trace/trace_syscalls.c

+67 −1
Original line number Diff line number Diff line
@@ -191,6 +191,67 @@ int syscall_enter_format(struct ftrace_event_call *call, struct trace_seq *s) 
	return trace_seq_putc(s, '\n');

}



static

int  __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)

{

	int i;

	int pos = 0;



	/* When len=0, we just calculate the needed length */

#define LEN_OR_ZERO (len ? len - pos : 0)



	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");

	for (i = 0; i < entry->nb_args; i++) {

		pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",

				entry->args[i], sizeof(unsigned long),

				i == entry->nb_args - 1 ? "" : ", ");

	}

	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");



	for (i = 0; i < entry->nb_args; i++) {

		pos += snprintf(buf + pos, LEN_OR_ZERO,

				", ((unsigned long)(REC->%s))", entry->args[i]);

	}



#undef LEN_OR_ZERO



	/* return the length of print_fmt */

	return pos;

}



static int set_syscall_print_fmt(struct ftrace_event_call *call)

{

	char *print_fmt;

	int len;

	struct syscall_metadata *entry = call->data;



	if (entry->enter_event != call) {

		call->print_fmt = "\"0x%lx\", REC->ret";

		return 0;

	}



	/* First: called with 0 length to calculate the needed length */

	len = __set_enter_print_fmt(entry, NULL, 0);



	print_fmt = kmalloc(len + 1, GFP_KERNEL);

	if (!print_fmt)

		return -ENOMEM;



	/* Second: actually write the @print_fmt */

	__set_enter_print_fmt(entry, print_fmt, len + 1);

	call->print_fmt = print_fmt;



	return 0;

}



static void free_syscall_print_fmt(struct ftrace_event_call *call)

{

	struct syscall_metadata *entry = call->data;



	if (entry->enter_event == call)

		kfree(call->print_fmt);

}



int syscall_exit_format(struct ftrace_event_call *call, struct trace_seq *s)

{

	int ret;
@@ -386,9 +447,14 @@ int init_syscall_trace(struct ftrace_event_call *call) 
{

	int id;



	if (set_syscall_print_fmt(call) < 0)

		return -ENOMEM;



	id = register_ftrace_event(call->event);

	if (!id)

	if (!id) {

		free_syscall_print_fmt(call);

		return -ENODEV;

	}

	call->id = id;

	INIT_LIST_HEAD(&call->fields);

	return 0;