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Commit 3d9a8072 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

tracing: Cleanup stack trace code 



- Remove the extra array member of stack_dump_trace[] along with the
  ARRAY_SIZE - 1 initialization for struct stack_trace :: max_entries.

  Both are historical leftovers of no value. The stack tracer never exceeds
  the array and there is no extra storage requirement either.

- Make variables which are only used in trace_stack.c static.

- Simplify the enable/disable logic.

- Rename stack_trace_print() as it's using the stack_trace_ namespace. Free
  the name up for stack trace related functions.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: David Rientjes <rientjes@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org
Cc: dm-devel@redhat.com
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: linux-arch@vger.kernel.org
Link: https://lkml.kernel.org/r/20190425094801.230654524@linutronix.de
parent 4285f2fc

include/linux/ftrace.h

+4 −14
Original line number Diff line number Diff line
@@ -241,19 +241,9 @@ static inline void ftrace_free_mem(struct module *mod, void *start, void *end) { 


#ifdef CONFIG_STACK_TRACER



#define STACK_TRACE_ENTRIES 500



struct stack_trace;



extern unsigned stack_trace_index[];

extern struct stack_trace stack_trace_max;

extern unsigned long stack_trace_max_size;

extern arch_spinlock_t stack_trace_max_lock;



extern int stack_tracer_enabled;

void stack_trace_print(void);

int

stack_trace_sysctl(struct ctl_table *table, int write,



int stack_trace_sysctl(struct ctl_table *table, int write,

		       void __user *buffer, size_t *lenp,

		       loff_t *ppos);

kernel/trace/trace_stack.c

+13 −29
Original line number Diff line number Diff line
@@ -18,30 +18,26 @@ 


#include "trace.h"



static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES + 1];

unsigned stack_trace_index[STACK_TRACE_ENTRIES];

#define STACK_TRACE_ENTRIES 500



static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES];

static unsigned stack_trace_index[STACK_TRACE_ENTRIES];



/*

 * Reserve one entry for the passed in ip. This will allow

 * us to remove most or all of the stack size overhead

 * added by the stack tracer itself.

 */

struct stack_trace stack_trace_max = {

	.max_entries		= STACK_TRACE_ENTRIES - 1,

	.max_entries		= STACK_TRACE_ENTRIES,

	.entries		= &stack_dump_trace[0],

};



unsigned long stack_trace_max_size;

arch_spinlock_t stack_trace_max_lock =

static unsigned long stack_trace_max_size;

static arch_spinlock_t stack_trace_max_lock =

	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;



DEFINE_PER_CPU(int, disable_stack_tracer);

static DEFINE_MUTEX(stack_sysctl_mutex);



int stack_tracer_enabled;

static int last_stack_tracer_enabled;



void stack_trace_print(void)

static void print_max_stack(void)

{

	long i;

	int size;
@@ -61,16 +57,7 @@ void stack_trace_print(void) 
	}

}



/*

 * When arch-specific code overrides this function, the following

 * data should be filled up, assuming stack_trace_max_lock is held to

 * prevent concurrent updates.

 *     stack_trace_index[]

 *     stack_trace_max

 *     stack_trace_max_size

 */

void __weak

check_stack(unsigned long ip, unsigned long *stack)

static void check_stack(unsigned long ip, unsigned long *stack)

{

	unsigned long this_size, flags; unsigned long *p, *top, *start;

	static int tracer_frame;
@@ -179,7 +166,7 @@ check_stack(unsigned long ip, unsigned long *stack) 
	stack_trace_max.nr_entries = x;



	if (task_stack_end_corrupted(current)) {

		stack_trace_print();

		print_max_stack();

		BUG();

	}
@@ -412,23 +399,21 @@ stack_trace_sysctl(struct ctl_table *table, int write, 
		   void __user *buffer, size_t *lenp,

		   loff_t *ppos)

{

	int was_enabled;

	int ret;



	mutex_lock(&stack_sysctl_mutex);

	was_enabled = !!stack_tracer_enabled;



	ret = proc_dointvec(table, write, buffer, lenp, ppos);



	if (ret || !write ||

	    (last_stack_tracer_enabled == !!stack_tracer_enabled))

	if (ret || !write || (was_enabled == !!stack_tracer_enabled))

		goto out;



	last_stack_tracer_enabled = !!stack_tracer_enabled;



	if (stack_tracer_enabled)

		register_ftrace_function(&trace_ops);

	else

		unregister_ftrace_function(&trace_ops);



 out:

	mutex_unlock(&stack_sysctl_mutex);

	return ret;
@@ -444,7 +429,6 @@ static __init int enable_stacktrace(char *str) 
		strncpy(stack_trace_filter_buf, str + len, COMMAND_LINE_SIZE);



	stack_tracer_enabled = 1;

	last_stack_tracer_enabled = 1;

	return 1;

}

__setup("stacktrace", enable_stacktrace);