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tracing: Unify the logic for function tracing options

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Currently the logic for dealing with the options for function tracing
has two different implementations. One is used when we set the flags
(in "static int func_set_flag()") and another used when we initialize
the tracer (in "static int function_trace_init()"). Those two
implementations are meant to do essentially the same thing and they
are both not very convenient for adding new options. In this patch
we add a helper function that provides a single implementation of
the logic for dealing with the options and we make it such that new
options can be easily added.

Link: https://lkml.kernel.org/r/20210415181854.147448-6-y.karadz@gmail.com

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Yordan Karadzhov (VMware) 2021-04-15 21:18:53 +03:00 committed by Steven Rostedt (VMware)
parent c658797f1a
commit 4994891ebb
1 changed files with 38 additions and 27 deletions
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65
kernel/trace/trace_functions.c
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@ -31,9 +31,12 @@ static struct tracer_flags func_flags;
/* Our option */
enum {
TRACE_FUNC_NO_OPTS = 0x0, /* No flags set. */
TRACE_FUNC_OPT_STACK = 0x1,
};
#define TRACE_FUNC_OPT_MASK (TRACE_FUNC_OPT_STACK)
int ftrace_allocate_ftrace_ops(struct trace_array *tr)
{
struct ftrace_ops *ops;
@ -86,6 +89,18 @@ void ftrace_destroy_function_files(struct trace_array *tr)
ftrace_free_ftrace_ops(tr);
}
static ftrace_func_t select_trace_function(u32 flags_val)
{
switch (flags_val & TRACE_FUNC_OPT_MASK) {
case TRACE_FUNC_NO_OPTS:
return function_trace_call;
case TRACE_FUNC_OPT_STACK:
return function_stack_trace_call;
default:
return NULL;
}
}
static int function_trace_init(struct trace_array *tr)
{
ftrace_func_t func;
@ -97,12 +112,9 @@ static int function_trace_init(struct trace_array *tr)
if (!tr->ops)
return -ENOMEM;
/* Currently only the global instance can do stack tracing */
if (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
func_flags.val & TRACE_FUNC_OPT_STACK)
func = function_stack_trace_call;
else
func = function_trace_call;
func = select_trace_function(func_flags.val);
if (!func)
return -EINVAL;
ftrace_init_array_ops(tr, func);
@ -213,7 +225,7 @@ static struct tracer_opt func_opts[] = {
};
static struct tracer_flags func_flags = {
.val = 0, /* By default: all flags disabled */
.val = TRACE_FUNC_NO_OPTS, /* By default: all flags disabled */
.opts = func_opts
};
@ -235,30 +247,29 @@ static struct tracer function_trace;
static int
func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
{
switch (bit) {
case TRACE_FUNC_OPT_STACK:
/* do nothing if already set */
if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
break;
ftrace_func_t func;
u32 new_flags;
/* We can change this flag when not running. */
if (tr->current_trace != &function_trace)
break;
/* Do nothing if already set. */
if (!!set == !!(func_flags.val & bit))
return 0;
unregister_ftrace_function(tr->ops);
/* We can change this flag only when not running. */
if (tr->current_trace != &function_trace)
return 0;
if (set) {
tr->ops->func = function_stack_trace_call;
register_ftrace_function(tr->ops);
} else {
tr->ops->func = function_trace_call;
register_ftrace_function(tr->ops);
}
break;
default:
new_flags = (func_flags.val & ~bit) | (set ? bit : 0);
func = select_trace_function(new_flags);
if (!func)
return -EINVAL;
}
/* Check if there's anything to change. */
if (tr->ops->func == func)
return 0;
unregister_ftrace_function(tr->ops);
tr->ops->func = func;
register_ftrace_function(tr->ops);
return 0;
}