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Date: Fri, 6 Dec 2013 21:28:03 -0500
From: Greg Price <price@....EDU>
To: "Theodore Ts'o" <tytso@....edu>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] random: clarify bits/bytes in wakeup thresholds
These are a recurring cause of confusion, so rename them to
hopefully be clearer.
Signed-off-by: Greg Price <price@....edu>
---
drivers/char/random.c | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index dc9b9af20..3f87a7e88 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -295,14 +295,14 @@
* The minimum number of bits of entropy before we wake up a read on
* /dev/random. Should be enough to do a significant reseed.
*/
-static int random_read_wakeup_thresh = 64;
+static int random_read_wakeup_bits = 64;
/*
* If the entropy count falls under this number of bits, then we
* should wake up processes which are selecting or polling on write
* access to /dev/random.
*/
-static int random_write_wakeup_thresh = 28 * OUTPUT_POOL_WORDS;
+static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
/*
* The minimum number of seconds between urandom pool resending. We
@@ -669,7 +669,7 @@ retry:
int entropy_bits = entropy_count >> ENTROPY_SHIFT;
/* should we wake readers? */
- if (entropy_bits >= random_read_wakeup_thresh) {
+ if (entropy_bits >= random_read_wakeup_bits) {
wake_up_interruptible(&random_read_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
}
@@ -678,9 +678,9 @@ retry:
* forth between them, until the output pools are 75%
* full.
*/
- if (entropy_bits > random_write_wakeup_thresh &&
+ if (entropy_bits > random_write_wakeup_bits &&
r->initialized &&
- r->entropy_total >= 2*random_read_wakeup_thresh) {
+ r->entropy_total >= 2*random_read_wakeup_bits) {
static struct entropy_store *last = &blocking_pool;
struct entropy_store *other = &blocking_pool;
@@ -924,19 +924,19 @@ static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
{
__u32 tmp[OUTPUT_POOL_WORDS];
- /* For /dev/random's pool, always leave two wakeup worth's BITS */
- int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4;
+ /* For /dev/random's pool, always leave two wakeups' worth */
+ int rsvd_bytes = r->limit ? 0 : random_read_wakeup_bits / 4;
int bytes = nbytes;
- /* pull at least as many as BYTES as wakeup BITS */
- bytes = max_t(int, bytes, random_read_wakeup_thresh / 8);
+ /* pull at least as much as a wakeup */
+ bytes = max_t(int, bytes, random_read_wakeup_bits / 8);
/* but never more than the buffer size */
bytes = min_t(int, bytes, sizeof(tmp));
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);
+ random_read_wakeup_bits / 8, rsvd_bytes);
mix_pool_bytes(r, tmp, bytes, NULL);
credit_entropy_bits(r, bytes*8);
}
@@ -952,7 +952,7 @@ static void push_to_pool(struct work_struct *work)
struct entropy_store *r = container_of(work, struct entropy_store,
push_work);
BUG_ON(!r);
- _xfer_secondary_pool(r, random_read_wakeup_thresh/8);
+ _xfer_secondary_pool(r, random_read_wakeup_bits/8);
trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT,
r->pull->entropy_count >> ENTROPY_SHIFT);
}
@@ -1004,7 +1004,7 @@ retry:
goto retry;
if ((r->entropy_count >> ENTROPY_SHIFT)
- < random_write_wakeup_thresh)
+ < random_write_wakeup_bits)
wakeup_write = 1;
}
spin_unlock_irqrestore(&r->lock, flags);
@@ -1313,7 +1313,7 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
wait_event_interruptible(random_read_wait,
ENTROPY_BITS(&input_pool) >=
- random_read_wakeup_thresh);
+ random_read_wakeup_bits);
if (signal_pending(current)) {
retval = -ERESTARTSYS;
@@ -1358,9 +1358,9 @@ random_poll(struct file *file, poll_table * wait)
poll_wait(file, &random_read_wait, wait);
poll_wait(file, &random_write_wait, wait);
mask = 0;
- if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_thresh)
+ if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)
mask |= POLLIN | POLLRDNORM;
- if (ENTROPY_BITS(&input_pool) < random_write_wakeup_thresh)
+ if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
mask |= POLLOUT | POLLWRNORM;
return mask;
}
@@ -1583,7 +1583,7 @@ struct ctl_table random_table[] = {
},
{
.procname = "read_wakeup_threshold",
- .data = &random_read_wakeup_thresh,
+ .data = &random_read_wakeup_bits,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
@@ -1592,7 +1592,7 @@ struct ctl_table random_table[] = {
},
{
.procname = "write_wakeup_threshold",
- .data = &random_write_wakeup_thresh,
+ .data = &random_write_wakeup_bits,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
--
1.8.3.2
--
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