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Commit 3c289ba7 authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

blktrace: remove blk_probe_mutex 



blk_register_tracepoints() always returns 0, so make it return void,
thus we don't need to use blk_probe_mutex to protect blk_probes_ref.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49C2F5EA.8060606@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5006ea73

kernel/trace/blktrace.c

+5 −22
Original line number Diff line number Diff line
@@ -47,10 +47,9 @@ static struct tracer_flags blk_tracer_flags = { 
};



/* Global reference count of probes */

static DEFINE_MUTEX(blk_probe_mutex);

static atomic_t blk_probes_ref = ATOMIC_INIT(0);



static int blk_register_tracepoints(void);

static void blk_register_tracepoints(void);

static void blk_unregister_tracepoints(void);



/*
@@ -256,10 +255,8 @@ static void blk_trace_cleanup(struct blk_trace *bt) 
	free_percpu(bt->sequence);

	free_percpu(bt->msg_data);

	kfree(bt);

	mutex_lock(&blk_probe_mutex);

	if (atomic_dec_and_test(&blk_probes_ref))

		blk_unregister_tracepoints();

	mutex_unlock(&blk_probe_mutex);

}



int blk_trace_remove(struct request_queue *q)
@@ -471,13 +468,8 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, 
	bt->pid = buts->pid;

	bt->trace_state = Blktrace_setup;



	mutex_lock(&blk_probe_mutex);

	if (atomic_add_return(1, &blk_probes_ref) == 1) {

		ret = blk_register_tracepoints();

		if (ret)

			goto probe_err;

	}

	mutex_unlock(&blk_probe_mutex);

	if (atomic_add_return(1, &blk_probes_ref) == 1)

		blk_register_tracepoints();



	ret = -EBUSY;

	old_bt = xchg(&q->blk_trace, bt);
@@ -487,9 +479,6 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, 
	}



	return 0;

probe_err:

	atomic_dec(&blk_probes_ref);

	mutex_unlock(&blk_probe_mutex);

err:

	if (bt) {

		if (bt->msg_file)
@@ -863,7 +852,7 @@ void blk_add_driver_data(struct request_queue *q, 
}

EXPORT_SYMBOL_GPL(blk_add_driver_data);



static int blk_register_tracepoints(void)

static void blk_register_tracepoints(void)

{

	int ret;
@@ -901,7 +890,6 @@ static int blk_register_tracepoints(void) 
	WARN_ON(ret);

	ret = register_trace_block_remap(blk_add_trace_remap);

	WARN_ON(ret);

	return 0;

}



static void blk_unregister_tracepoints(void)
@@ -1099,11 +1087,8 @@ static void blk_tracer_print_header(struct seq_file *m) 


static void blk_tracer_start(struct trace_array *tr)

{

	mutex_lock(&blk_probe_mutex);

	if (atomic_add_return(1, &blk_probes_ref) == 1)

		if (blk_register_tracepoints())

			atomic_dec(&blk_probes_ref);

	mutex_unlock(&blk_probe_mutex);

		blk_register_tracepoints();

	trace_flags &= ~TRACE_ITER_CONTEXT_INFO;

}
@@ -1118,10 +1103,8 @@ static int blk_tracer_init(struct trace_array *tr) 
static void blk_tracer_stop(struct trace_array *tr)

{

	trace_flags |= TRACE_ITER_CONTEXT_INFO;

	mutex_lock(&blk_probe_mutex);

	if (atomic_dec_and_test(&blk_probes_ref))

		blk_unregister_tracepoints();

	mutex_unlock(&blk_probe_mutex);

}



static void blk_tracer_reset(struct trace_array *tr)