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authorGreg Price <price@MIT.EDU>2013-11-30 00:02:33 +0400
committerTheodore Ts'o <tytso@mit.edu>2014-03-20 06:18:50 +0400
commit12ff3a517ab92b5496c731a3c354caa1f16c569f (patch)
tree598dfb6d4e4caa8ae10e8f04b76cd36d868e6ad3 /drivers/char/random.c
parent18e9cea74951b64282964f9625db94c5d5a007bd (diff)
downloadlinux-12ff3a517ab92b5496c731a3c354caa1f16c569f.tar.xz
random: simplify loop in random_read
The loop condition never changes until just before a break, so we might as well write it as a constant. Also since a996996dd75a ("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>
Diffstat (limited to 'drivers/char/random.c')
-rw-r--r--drivers/char/random.c57
1 files changed, 18 insertions, 39 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index fcda7d3937e0..fcc2bff8f887 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -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) {
- if (file->f_flags & O_NONBLOCK) {
- retval = -EAGAIN;
- break;
- }
-
- 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 */
+ if (n > 0)
+ return n;
+ /* Pool is (near) empty. Maybe wait and retry. */
+
+ 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))
+ return -ERESTARTSYS;
}
-
- return (count ? count : retval);
}
static ssize_t