From 2132a96f66b6b4d865113e7d4cb56d5f7c6e3cdf Mon Sep 17 00:00:00 2001 From: Greg Price Date: Fri, 6 Dec 2013 21:28:03 -0500 Subject: 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 Signed-off-by: "Theodore Ts'o" --- 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 581d806..8cc7d65 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 reseeding. 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); } @@ -987,7 +987,7 @@ retry: trace_debit_entropy(r->name, 8 * ibytes); if (ibytes && - (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_thresh) { + (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) { wake_up_interruptible(&random_write_wait); kill_fasync(&fasync, SIGIO, POLL_OUT); } @@ -1303,7 +1303,7 @@ 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)) return -ERESTARTSYS; } @@ -1334,9 +1334,9 @@ 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; } @@ -1559,7 +1559,7 @@ 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, @@ -1568,7 +1568,7 @@ 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, -- cgit v1.1