Release 4.15 kernel/trace/blktrace.c

/*
 * Copyright (C) 2006 Jens Axboe <axboe@kernel.dk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */
#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/blktrace_api.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/debugfs.h>
#include <linux/export.h>
#include <linux/time.h>
#include <linux/uaccess.h>
#include <linux/list.h>
#include <linux/blk-cgroup.h>

#include "../../block/blk.h"

#include <trace/events/block.h>

#include "trace_output.h"

#ifdef CONFIG_BLK_DEV_IO_TRACE


static unsigned int blktrace_seq __read_mostly = 1;


static struct trace_array *blk_tr;

static bool blk_tracer_enabled __read_mostly;

static LIST_HEAD(running_trace_list);
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);

/* Select an alternative, minimalistic output than the original one */

#define TRACE_BLK_OPT_CLASSIC	0x1

#define TRACE_BLK_OPT_CGROUP	0x2

#define TRACE_BLK_OPT_CGNAME	0x4


static struct tracer_opt blk_tracer_opts[] = {
	/* Default disable the minimalistic output */
	{ TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
#ifdef CONFIG_BLK_CGROUP
	{ TRACER_OPT(blk_cgroup, TRACE_BLK_OPT_CGROUP) },
	{ TRACER_OPT(blk_cgname, TRACE_BLK_OPT_CGNAME) },
#endif
	{ }
};


static struct tracer_flags blk_tracer_flags = {
	.val  = 0,
	.opts = blk_tracer_opts,
};

/* Global reference count of probes */
static DEFINE_MUTEX(blk_probe_mutex);

static int blk_probes_ref;

static void blk_register_tracepoints(void);
static void blk_unregister_tracepoints(void);

/*
 * Send out a notify message.
 */


static void trace_note(struct blk_trace *bt, pid_t pid, int action,
		       const void *data, size_t len,
		       union kernfs_node_id *cgid)
{
	struct blk_io_trace *t;
	struct ring_buffer_event *event = NULL;
	struct ring_buffer *buffer = NULL;
	int pc = 0;
	int cpu = smp_processor_id();
	bool blk_tracer = blk_tracer_enabled;
	ssize_t cgid_len = cgid ? sizeof(*cgid) : 0;

	if (blk_tracer) {
		buffer = blk_tr->trace_buffer.buffer;
		pc = preempt_count();
		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
						  sizeof(*t) + len + cgid_len,
						  0, pc);
		if (!event)
			return;
		t = ring_buffer_event_data(event);
		goto record_it;
	}

	if (!bt->rchan)
		return;

	t = relay_reserve(bt->rchan, sizeof(*t) + len + cgid_len);
	if (t) {
		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
		t->time = ktime_to_ns(ktime_get());
record_it:
		t->device = bt->dev;
		t->action = action | (cgid ? __BLK_TN_CGROUP : 0);
		t->pid = pid;
		t->cpu = cpu;
		t->pdu_len = len + cgid_len;
		if (cgid)
			memcpy((void *)t + sizeof(*t), cgid, cgid_len);
		memcpy((void *) t + sizeof(*t) + cgid_len, data, len);

		if (blk_tracer)
			trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
	}
}

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Jens Axboe
92
31.51%
3
25.00%
Li Zefan
86
29.45%
1
8.33%
Shaohua Li
57
19.52%
1
8.33%
Olaf Kirch
26
8.90%
1
8.33%
Steven Rostedt
19
6.51%
3
25.00%
Arnaldo Carvalho de Melo
8
2.74%
1
8.33%
Ingo Molnar
4
1.37%
2
16.67%
Total
292
100.00%
12
100.00%

/*
 * Send out a notify for this process, if we haven't done so since a trace
 * started
 */


static void trace_note_tsk(struct task_struct *tsk)
{
	unsigned long flags;
	struct blk_trace *bt;

	tsk->btrace_seq = blktrace_seq;
	spin_lock_irqsave(&running_trace_lock, flags);
	list_for_each_entry(bt, &running_trace_list, running_list) {
		trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm,
			   sizeof(tsk->comm), NULL);
	}
	spin_unlock_irqrestore(&running_trace_lock, flags);
}

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Jan Kara
35
46.05%
1
20.00%
Olaf Kirch
31
40.79%
1
20.00%
Jens Axboe
8
10.53%
2
40.00%
Shaohua Li
2
2.63%
1
20.00%
Total
76
100.00%
5
100.00%



static void trace_note_time(struct blk_trace *bt)
{
	struct timespec64 now;
	unsigned long flags;
	u32 words[2];

	/* need to check user space to see if this breaks in y2038 or y2106 */
	ktime_get_real_ts64(&now);
	words[0] = (u32)now.tv_sec;
	words[1] = now.tv_nsec;

	local_irq_save(flags);
	trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words), NULL);
	local_irq_restore(flags);
}

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Olaf Kirch
72
88.89%
1
25.00%
Arnd Bergmann
6
7.41%
1
25.00%
Shaohua Li
2
2.47%
1
25.00%
Jens Axboe
1
1.23%
1
25.00%
Total
81
100.00%
4
100.00%



void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
	const char *fmt, ...)
{
	int n;
	va_list args;
	unsigned long flags;
	char *buf;

	if (unlikely(bt->trace_state != Blktrace_running &&
		     !blk_tracer_enabled))
		return;

	/*
         * If the BLK_TC_NOTIFY action mask isn't set, don't send any note
         * message to the trace.
         */
	if (!(bt->act_mask & BLK_TC_NOTIFY))
		return;

	local_irq_save(flags);
	buf = this_cpu_ptr(bt->msg_data);
	va_start(args, fmt);
	n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
	va_end(args);

	if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
		blkcg = NULL;
#ifdef CONFIG_BLK_CGROUP
	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n,
		blkcg ? cgroup_get_kernfs_id(blkcg->css.cgroup) : NULL);
#else
	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, NULL);
#endif
	local_irq_restore(flags);
}
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Alan D. Brunelle
61
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1
11.11%
Shaohua Li
55
32.16%
2
22.22%
Jens Axboe
14
8.19%
1
11.11%
Tao Ma
13
7.60%
1
11.11%
Carl Henrik Lunde
12
7.02%
1
11.11%
Li Zefan
8
4.68%
1
11.11%
Arnaldo Carvalho de Melo
7
4.09%
1
11.11%
Shan Wei
1
0.58%
1
11.11%
Total
171
100.00%
9
100.00%


EXPORT_SYMBOL_GPL(__trace_note_message);



static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
			 pid_t pid)
{
	if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
		return 1;
	if (sector && (sector < bt->start_lba || sector > bt->end_lba))
		return 1;
	if (bt->pid && pid != bt->pid)
		return 1;

	return 0;
}

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94.87%
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Shawn Du
4
5.13%
1
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78
100.00%
2
100.00%

/*
 * Data direction bit lookup
 */

static const u32 ddir_act[2] = { BLK_TC_ACT(BLK_TC_READ),
				 BLK_TC_ACT(BLK_TC_WRITE) };


#define BLK_TC_RAHEAD		BLK_TC_AHEAD

#define BLK_TC_PREFLUSH		BLK_TC_FLUSH

/* The ilog2() calls fall out because they're constant */

#define MASK_TC_BIT(rw, __name) ((rw & REQ_ ## __name) << \
          (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT - __REQ_ ## __name))

/*
 * The worker for the various blk_add_trace*() types. Fills out a
 * blk_io_trace structure and places it in a per-cpu subbuffer.
 */


static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
		     int op, int op_flags, u32 what, int error, int pdu_len,
		     void *pdu_data, union kernfs_node_id *cgid)
{
	struct task_struct *tsk = current;
	struct ring_buffer_event *event = NULL;
	struct ring_buffer *buffer = NULL;
	struct blk_io_trace *t;
	unsigned long flags = 0;
	unsigned long *sequence;
	pid_t pid;
	int cpu, pc = 0;
	bool blk_tracer = blk_tracer_enabled;
	ssize_t cgid_len = cgid ? sizeof(*cgid) : 0;

	if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
		return;

	what |= ddir_act[op_is_write(op) ? WRITE : READ];
	what |= MASK_TC_BIT(op_flags, SYNC);
	what |= MASK_TC_BIT(op_flags, RAHEAD);
	what |= MASK_TC_BIT(op_flags, META);
	what |= MASK_TC_BIT(op_flags, PREFLUSH);
	what |= MASK_TC_BIT(op_flags, FUA);
	if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE)
		what |= BLK_TC_ACT(BLK_TC_DISCARD);
	if (op == REQ_OP_FLUSH)
		what |= BLK_TC_ACT(BLK_TC_FLUSH);
	if (cgid)
		what |= __BLK_TA_CGROUP;

	pid = tsk->pid;
	if (act_log_check(bt, what, sector, pid))
		return;
	cpu = raw_smp_processor_id();

	if (blk_tracer) {
		tracing_record_cmdline(current);

		buffer = blk_tr->trace_buffer.buffer;
		pc = preempt_count();
		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
						  sizeof(*t) + pdu_len + cgid_len,
						  0, pc);
		if (!event)
			return;
		t = ring_buffer_event_data(event);
		goto record_it;
	}

	if (unlikely(tsk->btrace_seq != blktrace_seq))
		trace_note_tsk(tsk);

	/*
         * A word about the locking here - we disable interrupts to reserve
         * some space in the relay per-cpu buffer, to prevent an irq
         * from coming in and stepping on our toes.
         */
	local_irq_save(flags);
	t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);
	if (t) {
		sequence = per_cpu_ptr(bt->sequence, cpu);

		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
		t->sequence = ++(*sequence);
		t->time = ktime_to_ns(ktime_get());
record_it:
		/*
                 * These two are not needed in ftrace as they are in the
                 * generic trace_entry, filled by tracing_generic_entry_update,
                 * but for the trace_event->bin() synthesizer benefit we do it
                 * here too.
                 */
		t->cpu = cpu;
		t->pid = pid;

		t->sector = sector;
		t->bytes = bytes;
		t->action = what;
		t->device = bt->dev;
		t->error = error;
		t->pdu_len = pdu_len + cgid_len;

		if (cgid_len)
			memcpy((void *)t + sizeof(*t), cgid, cgid_len);
		if (pdu_len)
			memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);

		if (blk_tracer) {
			trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
			return;
		}
	}

	local_irq_restore(flags);
}

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Jens Axboe
247
47.50%
2
7.69%
Arnaldo Carvalho de Melo
102
19.62%
6
23.08%
Shaohua Li
57
10.96%
1
3.85%
Michael Christie
39
7.50%
3
11.54%
Steven Rostedt
19
3.65%
3
11.54%
David Woodhouse
14
2.69%
2
7.69%
Namhyung Kim
12
2.31%
1
3.85%
Li Zefan
9
1.73%
2
7.69%
Jan Kara
6
1.15%
1
3.85%
Nathan Scott
5
0.96%
1
3.85%
Adrian Hunter
4
0.77%
1
3.85%
Ingo Molnar
4
0.77%
2
7.69%
Christoph Hellwig
2
0.38%
1
3.85%
Total
520
100.00%
26
100.00%



static void blk_trace_free(struct blk_trace *bt)
{
	debugfs_remove(bt->msg_file);
	debugfs_remove(bt->dropped_file);
	relay_close(bt->rchan);
	debugfs_remove(bt->dir);
	free_percpu(bt->sequence);
	free_percpu(bt->msg_data);
	kfree(bt);
}

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Jens Axboe
40
68.97%
2
33.33%
Alan D. Brunelle
11
18.97%
2
33.33%
Stefan Raspl
5
8.62%
1
16.67%
Li Zefan
2
3.45%
1
16.67%
Total
58
100.00%
6
100.00%



static void get_probe_ref(void)
{
	mutex_lock(&blk_probe_mutex);
	if (++blk_probes_ref == 1)
		blk_register_tracepoints();
	mutex_unlock(&blk_probe_mutex);
}

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30
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1
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30
100.00%
1
100.00%



static void put_probe_ref(void)
{
	mutex_lock(&blk_probe_mutex);
	if (!--blk_probes_ref)
		blk_unregister_tracepoints();
	mutex_unlock(&blk_probe_mutex);
}

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29
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1
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static void blk_trace_cleanup(struct blk_trace *bt)
{
	blk_trace_free(bt);
	put_probe_ref();
}

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15
78.95%
1
25.00%
Arnaldo Carvalho de Melo
2
10.53%
1
25.00%
Jens Axboe
2
10.53%
2
50.00%
Total
19
100.00%
4
100.00%



static int __blk_trace_remove(struct request_queue *q)
{
	struct blk_trace *bt;

	bt = xchg(&q->blk_trace, NULL);
	if (!bt)
		return -EINVAL;

	if (bt->trace_state != Blktrace_running)
		blk_trace_cleanup(bt);

	return 0;
}

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51
96.23%
3
75.00%
Li Zefan
2
3.77%
1
25.00%
Total
53
100.00%
4
100.00%



int blk_trace_remove(struct request_queue *q)
{
	int ret;

	mutex_lock(&q->blk_trace_mutex);
	ret = __blk_trace_remove(q);
	mutex_unlock(&q->blk_trace_mutex);

	return ret;
}
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39
100.00%
1
100.00%


EXPORT_SYMBOL_GPL(blk_trace_remove);



static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
				size_t count, loff_t *ppos)
{
	struct blk_trace *bt = filp->private_data;
	char buf[16];

	snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));

	return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
}

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75
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1
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static const struct file_operations blk_dropped_fops = {
	.owner =	THIS_MODULE,
	.open =		simple_open,
	.read =		blk_dropped_read,
	.llseek =	default_llseek,
};



static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
				size_t count, loff_t *ppos)
{
	char *msg;
	struct blk_trace *bt;

	if (count >= BLK_TN_MAX_MSG)
		return -EINVAL;

	msg = memdup_user_nul(buffer, count);
	if (IS_ERR(msg))
		return PTR_ERR(msg);

	bt = filp->private_data;
	__trace_note_message(bt, NULL, "%s", msg);
	kfree(msg);

	return count;
}

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81
90.00%
1
25.00%
Al Viro
6
6.67%
1
25.00%
Shaohua Li
2
2.22%
1
25.00%
Li Zefan
1
1.11%
1
25.00%
Total
90
100.00%
4
100.00%


static const struct file_operations blk_msg_fops = {
	.owner =	THIS_MODULE,
	.open =		simple_open,
	.write =	blk_msg_write,
	.llseek =	noop_llseek,
};

/*
 * Keep track of how many times we encountered a full subbuffer, to aid
 * the user space app in telling how many lost events there were.
 */


static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
				     void *prev_subbuf, size_t prev_padding)
{
	struct blk_trace *bt;

	if (!relay_buf_full(buf))
		return 1;

	bt = buf->chan->private_data;
	atomic_inc(&bt->dropped);
	return 0;
}

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57
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1
100.00%



static int blk_remove_buf_file_callback(struct dentry *dentry)
{
	debugfs_remove(dentry);

	return 0;
}

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static struct dentry *blk_create_buf_file_callback(const char *filename,
						   struct dentry *parent,
						   umode_t mode,
						   struct rchan_buf *buf,
						   int *is_global)
{
	return debugfs_create_file(filename, mode, parent, buf,
					&relay_file_operations);
}

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1
2.22%
1
50.00%
Total
45
100.00%
2
100.00%


static struct rchan_callbacks blk_relay_callbacks = {
	.subbuf_start		= blk_subbuf_start_callback,
	.create_buf_file	= blk_create_buf_file_callback,
	.remove_buf_file	= blk_remove_buf_file_callback,
};



static void blk_trace_setup_lba(struct blk_trace *bt,
				struct block_device *bdev)
{
	struct hd_struct *part = NULL;

	if (bdev)
		part = bdev->bd_part;

	if (part) {
		bt->start_lba = part->start_sect;
		bt->end_lba = part->start_sect + part->nr_sects;
	} else {
		bt->start_lba = 0;
		bt->end_lba = -1ULL;
	}
}

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/*
 * Setup everything required to start tracing
 */


static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
			      struct block_device *bdev,
			      struct blk_user_trace_setup *buts)
{
	struct blk_trace *bt = NULL;
	struct dentry *dir = NULL;
	int ret;

	if (!buts->buf_size || !buts->buf_nr)
		return -EINVAL;

	strncpy(buts->name, name, BLKTRACE_BDEV_SIZE);
	buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0';

	/*
         * some device names have larger paths - convert the slashes
         * to underscores for this to work as expected
         */
	strreplace(buts->name, '/', '_');

	bt = kzalloc(sizeof(*bt), GFP_KERNEL);
	if (!bt)
		return -ENOMEM;

	ret = -ENOMEM;
	bt->sequence = alloc_percpu(unsigned long);
	if (!bt->sequence)
		goto err;

	bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
	if (!bt->msg_data)
		goto err;

	ret = -ENOENT;

	if (!blk_debugfs_root)
		goto err;

	dir = debugfs_lookup(buts->name, blk_debugfs_root);
	if (!dir)
		bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
	if (!dir)
		goto err;

	bt->dev = dev;
	atomic_set(&bt->dropped, 0);
	INIT_LIST_HEAD(&bt->running_list);

	ret = -EIO;
	bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt,
					       &blk_dropped_fops);
	if (!bt->dropped_file)
		goto err;

	bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
	if (!bt->msg_file)
		goto err;

	bt->rchan = relay_open("trace", dir, buts->buf_size,
				buts->buf_nr, &blk_relay_callbacks, bt);
	if (!bt->rchan)
		goto err;

	bt->act_mask = buts->act_mask;
	if (!bt->act_mask)
		bt->act_mask = (u16) -1;

	blk_trace_setup_lba(bt, bdev);

	/* overwrite with user settings */
	if (buts->start_lba)
		bt->start_lba = buts->start_lba;
	if (buts->end_lba)
		bt->end_lba = buts->end_lba;

	bt->pid = buts->pid;
	bt->trace_state = Blktrace_setup;

	ret = -EBUSY;
	if (cmpxchg(&q->blk_trace, NULL, bt))
		goto err;

	get_probe_ref();

	ret = 0;
err:
	if (dir && !bt->dir)
		dput(dir);
	if (ret)
		blk_trace_free(bt);
	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Jens Axboe
306
65.38%
6
27.27%
Omar Sandoval
42
8.97%
3
13.64%
Alan D. Brunelle
32
6.84%
1
4.55%
Shawn Du
24
5.13%
1
4.55%
Li Zefan
20
4.27%
4
18.18%
Arnd Bergmann
13
2.78%
1
4.55%
Jan Kara
8
1.71%
1
4.55%
Christof Schmitt
7
1.50%
1
4.55%
Rusty Russell
5
1.07%
1
4.55%
Davidlohr Bueso A
5
1.07%
1
4.55%
Rasmus Villemoes
4
0.85%
1
4.55%
Mathieu Desnoyers
2
0.43%
1
4.55%
Total
468
100.00%
22
100.00%



static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
			     struct block_device *bdev, char __user *arg)
{
	struct blk_user_trace_setup buts;
	int ret;

	ret = copy_from_user(&buts, arg, sizeof(buts));
	if (ret)
		return -EFAULT;

	ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
	if (ret)
		return ret;

	if (copy_to_user(arg, &buts, sizeof(buts))) {
		__blk_trace_remove(q);
		return -EFAULT;
	}
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Arnd Bergmann
86
78.18%
1
16.67%
Christof Schmitt
8
7.27%
1
16.67%
Shawn Du
7
6.36%
1
16.67%
Dmitriy Monakhov
6
5.45%
1
16.67%
Jens Axboe
3
2.73%
2
33.33%
Total
110
100.00%
6
100.00%



int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
		    struct block_device *bdev,
		    char __user *arg)
{
	int ret;

	mutex_lock(&q->blk_trace_mutex);
	ret = __blk_trace_setup(q, name, dev, bdev, arg