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ftrace: make some tracers reentrant

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Now that the ring buffer is reentrant, some of the ftrace tracers
(sched_swich, debugging traces) can also be reentrant.

Note: Never make the function tracer reentrant, that can cause
  recursion problems all over the kernel. The function tracer
  must disable reentrancy.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-10-04 02:01:00 -04:00 committed by Ingo Molnar
parent bf41a158ca
commit 3ea2e6d71a
2 changed files with 4 additions and 16 deletions
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10
kernel/trace/trace.c
View File

@ -839,7 +839,6 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
long disabled;
int cpu;
int pc;
@ -850,12 +849,10 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
preempt_disable_notrace();
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
if (likely(!atomic_read(&data->disabled)))
ftrace_trace_special(tr, data, arg1, arg2, arg3, pc);
atomic_dec(&data->disabled);
preempt_enable_notrace();
}
@ -2961,7 +2958,6 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
struct trace_array_cpu *data;
struct print_entry *entry;
unsigned long flags, irq_flags;
long disabled;
int cpu, len = 0, size, pc;
if (!tr->ctrl || tracing_disabled)
@ -2971,9 +2967,8 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
preempt_disable_notrace();
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (unlikely(disabled != 1))
if (unlikely(atomic_read(&data->disabled)))
goto out;
spin_lock_irqsave(&trace_buf_lock, flags);
@ -2999,7 +2994,6 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
spin_unlock_irqrestore(&trace_buf_lock, flags);
out:
atomic_dec(&data->disabled);
preempt_enable_notrace();
return len;

10
kernel/trace/trace_sched_switch.c
View File

@ -24,7 +24,6 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
{
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
@ -41,12 +40,10 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = ctx_trace->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
if (likely(!atomic_read(&data->disabled)))
tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
@ -55,7 +52,6 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
{
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu, pc;
if (!likely(tracer_enabled))
@ -67,13 +63,11 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = ctx_trace->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
if (likely(!atomic_read(&data->disabled)))
tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
flags, pc);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}