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random: simplify loop in random_read

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The loop condition never changes until just before a break, so we
might as well write it as a constant.  Also since a996996dd7
("random: drop weird m_time/a_time manipulation") we don't do anything
after the loop finishes, so the 'break's might as well return
directly.  Some other simplifications.

There should be no change in behavior introduced by this commit.

Signed-off-by: Greg Price <price@mit.edu>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Greg Price 2013-11-29 15:02:33 -05:00 committed by Theodore Ts'o
parent 18e9cea749
commit 12ff3a517a
1 changed files with 16 additions and 37 deletions
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53
drivers/char/random.c
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@ -1285,53 +1285,32 @@ void rand_initialize_disk(struct gendisk *disk)
static ssize_t
random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
ssize_t n, retval = 0, count = 0;
ssize_t n;
if (nbytes == 0)
return 0;
while (nbytes > 0) {
n = nbytes;
if (n > SEC_XFER_SIZE)
n = SEC_XFER_SIZE;
n = extract_entropy_user(&blocking_pool, buf, n);
if (n < 0) {
retval = n;
break;
}
nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE);
while (1) {
n = extract_entropy_user(&blocking_pool, buf, nbytes);
if (n < 0)
return n;
trace_random_read(n*8, (nbytes-n)*8,
ENTROPY_BITS(&blocking_pool),
ENTROPY_BITS(&input_pool));
if (n > 0)
return n;
/* Pool is (near) empty. Maybe wait and retry. */
if (n == 0) {
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
wait_event_interruptible(random_read_wait,
ENTROPY_BITS(&input_pool) >=
random_read_wakeup_thresh);
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
continue;
}
count += n;
buf += n;
nbytes -= n;
break; /* This break makes the device work */
/* like a named pipe */
wait_event_interruptible(random_read_wait,
ENTROPY_BITS(&input_pool) >=
random_read_wakeup_thresh);
if (signal_pending(current))
return -ERESTARTSYS;
}
return (count ? count : retval);
}
static ssize_t