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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

arch/x86/kernel/ftrace.c

+2 −2
Original line number Original line Diff line number Diff line
@@ -113,7 +113,7 @@ static void ftrace_mod_code(void) 
					     MCOUNT_INSN_SIZE);

					     MCOUNT_INSN_SIZE);

}

}





void arch_ftrace_nmi_enter(void)

void ftrace_nmi_enter(void)

{

{

	atomic_inc(&nmi_running);

	atomic_inc(&nmi_running);

	/* Must have nmi_running seen before reading write flag */

	/* 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 */

	/* Finish all executions before clearing nmi_running */

	smp_wmb();

	smp_wmb();

include/linux/ftrace_irq.h

+0 −8
Original line number Original line Diff line number Diff line
@@ -3,14 +3,6 @@ 








#ifdef CONFIG_FTRACE_NMI_ENTER

#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_enter(void);

extern void ftrace_nmi_exit(void);

extern void ftrace_nmi_exit(void);

#else

#else

kernel/trace/ring_buffer.c

+13 −30
Original line number Original line Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/spinlock.h>

#include <linux/spinlock.h>

#include <linux/debugfs.h>

#include <linux/debugfs.h>

#include <linux/uaccess.h>

#include <linux/uaccess.h>

#include <linux/hardirq.h>

#include <linux/module.h>

#include <linux/module.h>

#include <linux/percpu.h>

#include <linux/percpu.h>

#include <linux/mutex.h>

#include <linux/mutex.h>
@@ -19,35 +20,6 @@ 




#include "trace.h"

#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

 * A fast way to enable or disable all ring buffers is to

 * call tracing_on or tracing_off. Turning off the ring buffers

 * 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);

		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.

		 * NMIs can happen after we take the lock.

		 * If we are in an NMI, only take the lock

		 * If we are in an NMI, only take the lock

		 * if it is not already taken. Otherwise

		 * if it is not already taken. Otherwise

		 * simply fail.

		 * simply fail.

		 */

		 */

		if (unlikely(__get_cpu_var(rb_in_nmi))) {

		if (unlikely(in_nmi())) {

			if (!__raw_spin_trylock(&cpu_buffer->lock))

			if (!__raw_spin_trylock(&cpu_buffer->lock))

				goto out_unlock;

				goto out_unlock;

		} else

		} else