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Message-Id: <1380829509-10590-2-git-send-email-tytso@mit.edu>
Date: Thu, 3 Oct 2013 15:45:09 -0400
From: Theodore Ts'o <tytso@....edu>
To: Linux Kernel Developers List <linux-kernel@...r.kernel.org>
Cc: Theodore Ts'o <tytso@....edu>
Subject: [PATCH 2/2] 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: "Theodore Ts'o" <tytso@....edu>
---
drivers/char/random.c | 52 ++++++-----------
include/trace/events/random.h | 128 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 144 insertions(+), 36 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 84c576e..f126bd2 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -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
diff --git a/include/trace/events/random.h b/include/trace/events/random.h
index 527b5dc..805af6d 100644
--- a/include/trace/events/random.h
+++ b/include/trace/events/random.h
@@ -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 */
--
1.7.12.rc0.22.gcdd159b
--
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