Commit f80bbd8b authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

random: convert DEBUG_ENT to tracepoints 



Instead of using the random driver's ad-hoc DEBUG_ENT() mechanism, use
tracepoints instead.  This allows for a much more fine-grained control
of which debugging mechanism which a developer might need, and unifies
the debugging messages with all of the existing tracepoints.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 6265e169

drivers/char/random.c

+16 −36
Original line number Diff line number Diff line
@@ -404,17 +404,6 @@ static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); 
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);

static struct fasync_struct *fasync;



static bool debug;

module_param(debug, bool, 0644);

#define DEBUG_ENT(fmt, arg...) do { \

	if (debug) \

		printk(KERN_DEBUG "random %04d %04d %04d: " \

		fmt,\

		input_pool.entropy_count,\

		blocking_pool.entropy_count,\

		nonblocking_pool.entropy_count,\

		## arg); } while (0)



/**********************************************************************

 *

 * OS independent entropy store.   Here are the functions which handle
@@ -612,7 +601,6 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits) 
	if (!nbits)

		return;



	DEBUG_ENT("added %d entropy credits to %s\n", nbits, r->name);

retry:

	entropy_count = orig = ACCESS_ONCE(r->entropy_count);

	if (nfrac < 0) {
@@ -655,7 +643,9 @@ retry: 
	}



	if (entropy_count < 0) {

		DEBUG_ENT("negative entropy/overflow\n");

		pr_warn("random: negative entropy/overflow: pool %s count %d\n",

			r->name, entropy_count);

		WARN_ON(1);

		entropy_count = 0;

	} else if (entropy_count > pool_size)

		entropy_count = pool_size;
@@ -832,10 +822,10 @@ void add_input_randomness(unsigned int type, unsigned int code, 
	if (value == last_value)

		return;



	DEBUG_ENT("input event\n");

	last_value = value;

	add_timer_randomness(&input_timer_state,

			     (type << 4) ^ code ^ (code >> 4) ^ value);

	trace_add_input_randomness(ENTROPY_BITS(&input_pool));

}

EXPORT_SYMBOL_GPL(add_input_randomness);
@@ -890,10 +880,8 @@ void add_disk_randomness(struct gendisk *disk) 
	if (!disk || !disk->random)

		return;

	/* first major is 1, so we get >= 0x200 here */

	DEBUG_ENT("disk event %d:%d\n",

		  MAJOR(disk_devt(disk)), MINOR(disk_devt(disk)));



	add_timer_randomness(disk->random, 0x100 + disk_devt(disk));

	trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool));

}

#endif
@@ -941,10 +929,8 @@ static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes) 
	/* but never more than the buffer size */

	bytes = min_t(int, bytes, sizeof(tmp));



	DEBUG_ENT("going to reseed %s with %d bits (%zu of %d requested)\n",

		  r->name, bytes * 8, nbytes * 8,

		  r->entropy_count >> ENTROPY_SHIFT);



	trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8,

				  ENTROPY_BITS(r), ENTROPY_BITS(r->pull));

	bytes = extract_entropy(r->pull, tmp, bytes,

				random_read_wakeup_thresh / 8, rsvd);

	mix_pool_bytes(r, tmp, bytes, NULL);
@@ -992,8 +978,6 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min, 
	spin_lock_irqsave(&r->lock, flags);



	BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);

	DEBUG_ENT("trying to extract %zu bits from %s\n",

		  nbytes * 8, r->name);



	/* Can we pull enough? */

retry:
@@ -1019,12 +1003,9 @@ retry: 
		    < random_write_wakeup_thresh)

			wakeup_write = 1;

	}



	DEBUG_ENT("debiting %zu entropy credits from %s%s\n",

		  ibytes * 8, r->name, r->limit ? "" : " (unlimited)");



	spin_unlock_irqrestore(&r->lock, flags);



	trace_debit_entropy(r->name, 8 * ibytes);

	if (wakeup_write) {

		wake_up_interruptible(&random_write_wait);

		kill_fasync(&fasync, SIGIO, POLL_OUT);
@@ -1303,8 +1284,6 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) 
		if (n > SEC_XFER_SIZE)

			n = SEC_XFER_SIZE;



		DEBUG_ENT("reading %zu bits\n", n*8);



		n = extract_entropy_user(&blocking_pool, buf, n);



		if (n < 0) {
@@ -1312,8 +1291,9 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) 
			break;

		}



		DEBUG_ENT("read got %zd bits (%zd still needed)\n",

			  n*8, (nbytes-n)*8);

		trace_random_read(n*8, (nbytes-n)*8,

				  ENTROPY_BITS(&blocking_pool),

				  ENTROPY_BITS(&input_pool));



		if (n == 0) {

			if (file->f_flags & O_NONBLOCK) {
@@ -1321,14 +1301,10 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) 
				break;

			}



			DEBUG_ENT("sleeping?\n");



			wait_event_interruptible(random_read_wait,

				ENTROPY_BITS(&input_pool) >=

				random_read_wakeup_thresh);



			DEBUG_ENT("awake\n");



			if (signal_pending(current)) {

				retval = -ERESTARTSYS;

				break;
@@ -1350,7 +1326,11 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) 
static ssize_t

urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)

{

	return extract_entropy_user(&nonblocking_pool, buf, nbytes);

	int ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);



	trace_urandom_read(8 * nbytes, ENTROPY_BITS(&nonblocking_pool),

			   ENTROPY_BITS(&input_pool));

	return ret;

}



static unsigned int

include/trace/events/random.h

+128 −0
Original line number Diff line number Diff line
@@ -109,6 +109,89 @@ TRACE_EVENT(push_to_pool, 
		  __entry->input_bits)

);



TRACE_EVENT(debit_entropy,

	TP_PROTO(const char *pool_name, int debit_bits),



	TP_ARGS(pool_name, debit_bits),



	TP_STRUCT__entry(

		__field( const char *,	pool_name		)

		__field(	  int,	debit_bits		)

	),



	TP_fast_assign(

		__entry->pool_name	= pool_name;

		__entry->debit_bits	= debit_bits;

	),



	TP_printk("%s: debit_bits %d", __entry->pool_name,

		  __entry->debit_bits)

);



TRACE_EVENT(add_input_randomness,

	TP_PROTO(int input_bits),



	TP_ARGS(input_bits),



	TP_STRUCT__entry(

		__field(	  int,	input_bits		)

	),



	TP_fast_assign(

		__entry->input_bits	= input_bits;

	),



	TP_printk("input_pool_bits %d", __entry->input_bits)

);



TRACE_EVENT(add_disk_randomness,

	TP_PROTO(dev_t dev, int input_bits),



	TP_ARGS(dev, input_bits),



	TP_STRUCT__entry(

		__field(	dev_t,	dev			)

		__field(	  int,	input_bits		)

	),



	TP_fast_assign(

		__entry->dev		= dev;

		__entry->input_bits	= input_bits;

	),



	TP_printk("dev %d,%d input_pool_bits %d", MAJOR(__entry->dev),

		  MINOR(__entry->dev), __entry->input_bits)

);



TRACE_EVENT(xfer_secondary_pool,

	TP_PROTO(const char *pool_name, int xfer_bits, int request_bits,

		 int pool_entropy, int input_entropy),



	TP_ARGS(pool_name, xfer_bits, request_bits, pool_entropy,

		input_entropy),



	TP_STRUCT__entry(

		__field( const char *,	pool_name		)

		__field(	  int,	xfer_bits		)

		__field(	  int,	request_bits		)

		__field(	  int,	pool_entropy		)

		__field(	  int,	input_entropy		)

	),



	TP_fast_assign(

		__entry->pool_name	= pool_name;

		__entry->xfer_bits	= xfer_bits;

		__entry->request_bits	= request_bits;

		__entry->pool_entropy	= pool_entropy;

		__entry->input_entropy	= input_entropy;

	),



	TP_printk("pool %s xfer_bits %d request_bits %d pool_entropy %d "

		  "input_entropy %d", __entry->pool_name, __entry->xfer_bits,

		  __entry->request_bits, __entry->pool_entropy,

		  __entry->input_entropy)

);



DECLARE_EVENT_CLASS(random__get_random_bytes,

	TP_PROTO(int nbytes, unsigned long IP),
@@ -179,7 +262,52 @@ DEFINE_EVENT(random__extract_entropy, extract_entropy_user, 
	TP_ARGS(pool_name, nbytes, entropy_count, IP)

);



TRACE_EVENT(random_read,

	TP_PROTO(int got_bits, int need_bits, int pool_left, int input_left),



	TP_ARGS(got_bits, need_bits, pool_left, input_left),



	TP_STRUCT__entry(

		__field(	  int,	got_bits		)

		__field(	  int,	need_bits		)

		__field(	  int,	pool_left		)

		__field(	  int,	input_left		)

	),



	TP_fast_assign(

		__entry->got_bits	= got_bits;

		__entry->need_bits	= need_bits;

		__entry->pool_left	= pool_left;

		__entry->input_left	= input_left;

	),



	TP_printk("got_bits %d still_needed_bits %d "

		  "blocking_pool_entropy_left %d input_entropy_left %d",

		  __entry->got_bits, __entry->got_bits, __entry->pool_left,

		  __entry->input_left)

);



TRACE_EVENT(urandom_read,

	TP_PROTO(int got_bits, int pool_left, int input_left),



	TP_ARGS(got_bits, pool_left, input_left),



	TP_STRUCT__entry(

		__field(	  int,	got_bits		)

		__field(	  int,	pool_left		)

		__field(	  int,	input_left		)

	),



	TP_fast_assign(

		__entry->got_bits	= got_bits;

		__entry->pool_left	= pool_left;

		__entry->input_left	= input_left;

	),



	TP_printk("got_bits %d nonblocking_pool_entropy_left %d "

		  "input_entropy_left %d", __entry->got_bits,

		  __entry->pool_left, __entry->input_left)

);



#endif /* _TRACE_RANDOM_H */

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