Commit a81bd80a authored by Steven Rostedt's avatar Steven Rostedt
Browse files

ring-buffer: use generic version of in_nmi



Impact: clean up

Now that a generic in_nmi is available, this patch removes the
special code in the ring_buffer and implements the in_nmi generic
version instead.

With this change, I was also able to rename the "arch_ftrace_nmi_enter"
back to "ftrace_nmi_enter" and remove the code from the ring buffer.
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent 9a5fd902
......@@ -113,7 +113,7 @@ static void ftrace_mod_code(void)
MCOUNT_INSN_SIZE);
}
void arch_ftrace_nmi_enter(void)
void ftrace_nmi_enter(void)
{
atomic_inc(&nmi_running);
/* Must have nmi_running seen before reading write flag */
......@@ -124,7 +124,7 @@ void arch_ftrace_nmi_enter(void)
}
}
void arch_ftrace_nmi_exit(void)
void ftrace_nmi_exit(void)
{
/* Finish all executions before clearing nmi_running */
smp_wmb();
......
......@@ -3,14 +3,6 @@
#ifdef CONFIG_FTRACE_NMI_ENTER
extern void arch_ftrace_nmi_enter(void);
extern void arch_ftrace_nmi_exit(void);
#else
static inline void arch_ftrace_nmi_enter(void) { }
static inline void arch_ftrace_nmi_exit(void) { }
#endif
#ifdef CONFIG_RING_BUFFER
extern void ftrace_nmi_enter(void);
extern void ftrace_nmi_exit(void);
#else
......
......@@ -8,6 +8,7 @@
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/mutex.h>
......@@ -19,35 +20,6 @@
#include "trace.h"
/*
* Since the write to the buffer is still not fully lockless,
* we must be careful with NMIs. The locks in the writers
* are taken when a write crosses to a new page. The locks
* protect against races with the readers (this will soon
* be fixed with a lockless solution).
*
* Because we can not protect against NMIs, and we want to
* keep traces reentrant, we need to manage what happens
* when we are in an NMI.
*/
static DEFINE_PER_CPU(int, rb_in_nmi);
void ftrace_nmi_enter(void)
{
__get_cpu_var(rb_in_nmi)++;
/* call arch specific handler too */
arch_ftrace_nmi_enter();
}
void ftrace_nmi_exit(void)
{
arch_ftrace_nmi_exit();
__get_cpu_var(rb_in_nmi)--;
/* NMIs are not recursive */
WARN_ON_ONCE(__get_cpu_var(rb_in_nmi));
}
/*
* A fast way to enable or disable all ring buffers is to
* call tracing_on or tracing_off. Turning off the ring buffers
......@@ -1027,12 +999,23 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
local_irq_save(flags);
/*
* Since the write to the buffer is still not
* fully lockless, we must be careful with NMIs.
* The locks in the writers are taken when a write
* crosses to a new page. The locks protect against
* races with the readers (this will soon be fixed
* with a lockless solution).
*
* Because we can not protect against NMIs, and we
* want to keep traces reentrant, we need to manage
* what happens when we are in an NMI.
*
* NMIs can happen after we take the lock.
* If we are in an NMI, only take the lock
* if it is not already taken. Otherwise
* simply fail.
*/
if (unlikely(__get_cpu_var(rb_in_nmi))) {
if (unlikely(in_nmi())) {
if (!__raw_spin_trylock(&cpu_buffer->lock))
goto out_unlock;
} else
......
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