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ftrace: Kill FTRACE_OPS_FL_PER_CPU
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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>
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Peter Zijlstra authored and Steven Rostedt (VMware) committed Oct 16, 2017
1 parent 1dd311e commit b3a8880
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Showing 2 changed files with 20 additions and 118 deletions.
83 changes: 14 additions & 69 deletions include/linux/ftrace.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);

Expand Down
55 changes: 6 additions & 49 deletions kernel/trace/ftrace.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
/*
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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) {
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -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;
Expand Down

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