[for-next][PATCH 5/7] ftrace: Kill FTRACE_OPS_FL_PER_CPU

Steven Rostedt
2017-10-18T13:29:21Z

[-- Attachment #1: 0005-ftrace-Kill-FTRACE_OPS_FL_PER_CPU.patch --]
[-- Type: text/plain, Size: 9084 bytes --]

From: Peter Zijlstra <peterz@infradead.org>

The one and only user of FTRACE_OPS_FL_PER_CPU is gone, remove the
lot.

Link: http://lkml.kernel.org/r/20171011080224.372422809@infradead.org

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
include/linux/ftrace.h | 83 +++++++++-----------------------------------------
kernel/trace/ftrace.c | 55 ++++-----------------------------
2 files changed, 20 insertions(+), 118 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1f8545caa691..252e334e7b5f 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -102,10 +102,6 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
* ENABLED - set/unset when ftrace_ops is registered/unregistered
* DYNAMIC - set when ftrace_ops is registered to denote dynamically
* allocated ftrace_ops which need special care
- * PER_CPU - set manualy by ftrace_ops user to denote the ftrace_ops
- * could be controlled by following calls:
- * ftrace_function_local_enable
- * ftrace_function_local_disable
* SAVE_REGS - The ftrace_ops wants regs saved at each function called
* and passed to the callback. If this flag is set, but the
* architecture does not support passing regs
@@ -149,21 +145,20 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
enum {
FTRACE_OPS_FL_ENABLED = 1 << 0,
FTRACE_OPS_FL_DYNAMIC = 1 << 1,
- FTRACE_OPS_FL_PER_CPU = 1 << 2,
- FTRACE_OPS_FL_SAVE_REGS = 1 << 3,
- FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED = 1 << 4,
- FTRACE_OPS_FL_RECURSION_SAFE = 1 << 5,
- FTRACE_OPS_FL_STUB = 1 << 6,
- FTRACE_OPS_FL_INITIALIZED = 1 << 7,
- FTRACE_OPS_FL_DELETED = 1 << 8,
- FTRACE_OPS_FL_ADDING = 1 << 9,
- FTRACE_OPS_FL_REMOVING = 1 << 10,
- FTRACE_OPS_FL_MODIFYING = 1 << 11,
- FTRACE_OPS_FL_ALLOC_TRAMP = 1 << 12,
- FTRACE_OPS_FL_IPMODIFY = 1 << 13,
- FTRACE_OPS_FL_PID = 1 << 14,
- FTRACE_OPS_FL_RCU = 1 << 15,
- FTRACE_OPS_FL_TRACE_ARRAY = 1 << 16,
+ FTRACE_OPS_FL_SAVE_REGS = 1 << 2,
+ FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED = 1 << 3,
+ FTRACE_OPS_FL_RECURSION_SAFE = 1 << 4,
+ FTRACE_OPS_FL_STUB = 1 << 5,
+ FTRACE_OPS_FL_INITIALIZED = 1 << 6,
+ FTRACE_OPS_FL_DELETED = 1 << 7,
+ FTRACE_OPS_FL_ADDING = 1 << 8,
+ FTRACE_OPS_FL_REMOVING = 1 << 9,
+ FTRACE_OPS_FL_MODIFYING = 1 << 10,
+ FTRACE_OPS_FL_ALLOC_TRAMP = 1 << 11,
+ FTRACE_OPS_FL_IPMODIFY = 1 << 12,
+ FTRACE_OPS_FL_PID = 1 << 13,
+ FTRACE_OPS_FL_RCU = 1 << 14,
+ FTRACE_OPS_FL_TRACE_ARRAY = 1 << 15,
};

#ifdef CONFIG_DYNAMIC_FTRACE
@@ -198,7 +193,6 @@ struct ftrace_ops {
unsigned long flags;
void *private;
ftrace_func_t saved_func;
- int __percpu *disabled;
#ifdef CONFIG_DYNAMIC_FTRACE
struct ftrace_ops_hash local_hash;
struct ftrace_ops_hash *func_hash;
@@ -230,55 +224,6 @@ int register_ftrace_function(struct ftrace_ops *ops);
int unregister_ftrace_function(struct ftrace_ops *ops);
void clear_ftrace_function(void);

-/**
- * ftrace_function_local_enable - enable ftrace_ops on current cpu
- *
- * This function enables tracing on current cpu by decreasing
- * the per cpu control variable.
- * It must be called with preemption disabled and only on ftrace_ops
- * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
- * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
- */
-static inline void ftrace_function_local_enable(struct ftrace_ops *ops)
-{
- if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU)))
- return;
-
- (*this_cpu_ptr(ops->disabled))--;
-}
-
-/**
- * ftrace_function_local_disable - disable ftrace_ops on current cpu
- *
- * This function disables tracing on current cpu by increasing
- * the per cpu control variable.
- * It must be called with preemption disabled and only on ftrace_ops
- * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
- * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
- */
-static inline void ftrace_function_local_disable(struct ftrace_ops *ops)
-{
- if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU)))
- return;
-
- (*this_cpu_ptr(ops->disabled))++;
-}
-
-/**
- * ftrace_function_local_disabled - returns ftrace_ops disabled value
- * on current cpu
- *
- * This function returns value of ftrace_ops::disabled on current cpu.
- * It must be called with preemption disabled and only on ftrace_ops
- * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
- * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
- */
-static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
-{
- WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU));
- return *this_cpu_ptr(ops->disabled);
-}
-
extern void ftrace_stub(unsigned long a0, unsigned long a1,
struct ftrace_ops *op, struct pt_regs *regs);

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index e0a98225666b..2fd3edaec6de 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -203,30 +203,6 @@ void clear_ftrace_function(void)
ftrace_trace_function = ftrace_stub;
}

-static void per_cpu_ops_disable_all(struct ftrace_ops *ops)
-{
- int cpu;
-
- for_each_possible_cpu(cpu)
- *per_cpu_ptr(ops->disabled, cpu) = 1;
-}
-
-static int per_cpu_ops_alloc(struct ftrace_ops *ops)
-{
- int __percpu *disabled;
-
- if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU)))
- return -EINVAL;
-
- disabled = alloc_percpu(int);
- if (!disabled)
- return -ENOMEM;
-
- ops->disabled = disabled;
- per_cpu_ops_disable_all(ops);
- return 0;
-}
-
static void ftrace_sync(struct work_struct *work)
{
/*
@@ -262,8 +238,8 @@ static ftrace_func_t ftrace_ops_get_list_func(struct ftrace_ops *ops)
* If this is a dynamic, RCU, or per CPU ops, or we force list func,
* then it needs to call the list anyway.
*/
- if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_PER_CPU |
- FTRACE_OPS_FL_RCU) || FTRACE_FORCE_LIST_FUNC)
+ if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_RCU) ||
+ FTRACE_FORCE_LIST_FUNC)
return ftrace_ops_list_func;

return ftrace_ops_get_func(ops);
@@ -422,11 +398,6 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
if (!core_kernel_data((unsigned long)ops))
ops->flags |= FTRACE_OPS_FL_DYNAMIC;

- if (ops->flags & FTRACE_OPS_FL_PER_CPU) {
- if (per_cpu_ops_alloc(ops))
- return -ENOMEM;
- }
-
add_ftrace_ops(&ftrace_ops_list, ops);

/* Always save the function, and reset at unregistering */
@@ -2727,11 +2698,6 @@ void __weak arch_ftrace_trampoline_free(struct ftrace_ops *ops)
{
}

-static void per_cpu_ops_free(struct ftrace_ops *ops)
-{
- free_percpu(ops->disabled);
-}
-
static void ftrace_startup_enable(int command)
{
if (saved_ftrace_func != ftrace_trace_function) {
@@ -2833,7 +2799,7 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
* not currently active, we can just free them
* without synchronizing all CPUs.
*/
- if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_PER_CPU))
+ if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
goto free_ops;

return 0;
@@ -2880,7 +2846,7 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
* The same goes for freeing the per_cpu data of the per_cpu
* ops.
*/
- if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_PER_CPU)) {
+ if (ops->flags & FTRACE_OPS_FL_DYNAMIC) {
/*
* We need to do a hard force of sched synchronization.
* This is because we use preempt_disable() to do RCU, but
@@ -2903,9 +2869,6 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)

free_ops:
arch_ftrace_trampoline_free(ops);
-
- if (ops->flags & FTRACE_OPS_FL_PER_CPU)
- per_cpu_ops_free(ops);
}

return 0;
@@ -6355,10 +6318,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
* If any of the above fails then the op->func() is not executed.
*/
if ((!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching()) &&
- (!(op->flags & FTRACE_OPS_FL_PER_CPU) ||
- !ftrace_function_local_disabled(op)) &&
ftrace_ops_test(op, ip, regs)) {
-
if (FTRACE_WARN_ON(!op->func)) {
pr_warn("op=%p %pS\n", op, op);
goto out;
@@ -6416,10 +6376,7 @@ static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,

preempt_disable_notrace();

- if (!(op->flags & FTRACE_OPS_FL_PER_CPU) ||
- !ftrace_function_local_disabled(op)) {
- op->func(ip, parent_ip, op, regs);
- }
+ op->func(ip, parent_ip, op, regs);

preempt_enable_notrace();
trace_clear_recursion(bit);
@@ -6443,7 +6400,7 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops)
* or does per cpu logic, then we need to call the assist handler.
*/
if (!(ops->flags & FTRACE_OPS_FL_RECURSION_SAFE) ||
- ops->flags & (FTRACE_OPS_FL_RCU | FTRACE_OPS_FL_PER_CPU))
+ ops->flags & FTRACE_OPS_FL_RCU)
return ftrace_ops_assist_func;

return ops->func;
--
2.13.2